Signs and Marking Supplement
The Airport Safety and Operations Division issues this information to supplement Standards for Airport Markings, AC 150/5340-1.
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SIGNS and MARKING SUPPLEMENT #1
October 18, 19911. What is the FAA position on changing the taxiway designation at an airport?
The advisory circular calls for taxiways to be designated by letters of the alphabet. Optimally, the designations should start at one end of the airport and continue in order to the opposite end, e.g., north to south or east to west. However, as can be seen from Figure 2 in the advisory circular, the logic used to designate the taxiways when there are many crossing taxiways may not be readily apparent. While the FAA is not opposed to an airport operator redesignating an entire taxiway system in accordance with the advisory circular, we are only prepared to require the following:
- All taxiways shall be designated by alpha characters except for stub taxiways where it would be permissible to use an alphanumeric designation.
- Taxiways currently designated by numbers alone or the letters I, 0, or X are to be redesignated by alpha characters.
- Taxiways designated by local names or geographic position to an object, such as "Inner, Outer, North, and Bridge," are to be redesignated by alpha characters.
- The numbering of stub taxiways should be consecutive and be in the same direction for parallel runways. Where a planned exit is shown on the approved ALP, it is permissible to reserve the appropriate alphanumeric designator for it.
NOTE: Redesignating taxiways on an airport may result in confusion. To minimize this problem, the airport operator should develop an implementation plan to transition to the newly designated taxiways.
2. For stub taxiways designated with an alphanumeric, the standard does not provide for a dash between the alpha and numeric characters. For example, "Al" would be in accordance with the standard while "A-l" would not meet the standard. If an airport has signs with a dash between the alpha and the numeric that otherwise meet the standard, would they be acceptable?
The FAA would not require these signs to be replaced. However, if the signs are to be included in a sign array, all the signs in the array must comply with the requirements in Paragraph 13 of the advisory circular calling for the signs to be the same size and same height above ground.
3. What other existing signs would be acceptable?
For an existing sign to be acceptable, it would have to conform to the advisory circular's standards for color, installation, location, and, if required, have a properly aligned arrow. However, the use of a "dot" or "dash" on the sign as a message divider would require the sign to be replaced (except for stub taxiways as discussed in the preceding question.) If the existing sign is to be included as part of a sign array, all the signs in the array must be properly positioned, the same height and character size, and be lighted in the same manner (i.e., internally vs. externally.) The absence or presence of a border, the presence of arrows meeting the former standard, or the location of a vertical arrow on the left rather than the right of the alpha character would not preclude any existing sign from being acceptable.
4. Several existing signs have a black inscription on a yellow background and a vertical arrow to indicate a taxiway continues straight ahead. Are these signs acceptable?
In most cases these signs were used to provide pilots with the identity of the taxiway they were on. In these cases, the sign should be replaced by a location sign. If it is necessary to provide the pilot with information that a taxiway continues straight ahead, then the use of this sign is permissible if it is installed in a sign array with other appropriate direction signs and a location sign. This type of sign should never be installed by itself.
5. Do inbound destination signs with the inscription "RAMP" need to be replaced with the inscription "APRON"?
Assuming the sign with the inscription "RAMP" meets the current standard regarding color, location, and installation, these signs do not need to be replaced. Also if it is determined that additional destination signs are needed, the new sign inscriptions and existing sign inscriptions should be consistent. In other words, do not use two different inscriptions (e.g., RAMP and APRON) for the same destination.
6. What is the meaning of a dot vs. a dash on a sign?
On a sign face, a dot means "and." It appears on signs where one arrow is common to two designations. For example, if the route to two different runway ends involved the same taxiways, the runway numbers appearing on an outbound destination sign would be separated by a dot; the directional arrow appearing on the sign face would be applicable to both runway ends. See Figure 18 in the AC.
A dash should only be used on mandatory signs. On these signs, a dash is used to separate the designations for opposite ends of the same runway, e.g., 18-36 or to separate the runway designation from the abbreviation "APCH" on holding position signs for runway approach areas.
NOTE: In some past applications, the dot or the dash has been used to delineate between individual designations and their associated arrows that appeared in the same sign array, e.g., *D*E*. Under the new standard a vertical message bar is used to separate designations (see Paragraph 12.l). Consequently, signs that have dots or dashes that do not meet the current standard must be replaced.
7. When is it allowable to use only the designation of one runway end on a holding position sign for a taxiway/runway intersection?
The designation for one end of the runway should be used on the sign only when the taxiway intersects the beginning of that runway. Taxiways that intersect the runway at intermediate points must have the designations for both runway ends. Even if the taxiway intersects the runway end, it may still be necessary to include both designations on the sign if there is an operational need, e.g., if the taxiway is used as a crossing point. Also, holding position signs for taxiways that intersect the intersection of two runway ends require designations of both intersecting runway ends as shown in Figure 4b in the advisory circular.
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9. When is the holding position sign for runway approach areas used?
This sign should be used only on taxiways that pass through the approach area for a runway but do not intersect the runway. If it is necessary to protect the approach for a runway that the taxiway intersects, then
The standard runway holding position sign should be used if it is necessary to protect the runway approach for all operations. The ILS sign should be used if it is only necessary to protect the approach surface during precision instrument approaches.
10. How is the location of the holding position sign for the runway approach area determined?
The sign should be located so that an aircraft on the taxiway will not enter the runway safety area or penetrate any of the following surfaces that may be applicable to the runway: threshold location plane, inner approach obstacle free zone, inner transitional obstacle free zone, TERPS approach surfaces, and clearway. If the taxiway passes through a navigational aid critical area, it is also necessary to ensure that the sign is placed to protect this critical area if a separate "ILS" sign is not used.
11. When is the ILS sign used?
The ILS sign is used to protect the critical area for an ILS approach. The critical area includes the areas around the glide slope and localizer antennas necessary to protect the electronic signal, as well as any area where an aircraft on the ground would penetrate the airspace required by TERPS for an ILS approach. This latter case normally comes up in the case of an ILS approach to a displaced runway threshold. The ILS sign is not needed if these areas would be protected by the holding position sign for taxiway/runway intersections.
12. Paragraph 6c and 6d indicates that the boundary signs described in these paragraphs should not be installed on taxiways that have color coded centerline lights. What is meant by color coded centerline lights and why is the sign unnecessary?
Taxiway centerline lights are green. A change is being prepared to this standard. Under this change, every other centerline light in the area between the runway and the runway holding position marking (or ILS holding position marking if one is present) would be yellow. (NOTE: For existing installations, this change would only require replacing the green lenses with yellow ones.) Under this system, a pilot seeing a continuous line of green centerline lights will know that the applicable holding position marking has been passed. The signs described in these paragraph serve the same purpose; consequently, it was thought that the signs would not be needed if the alternating yellow and green centerline lights were present. Subsequent to the publication of the advisory circular, it was pointed out that there may be situations where a sign may be beneficial in addition to the color coded centerline lights, e.g., at airports where snow or ice may obscure the centerline lights. A change is being issued to the advisory circular to provide the option of installing these signs even if color coded centerline lights are present.
13. Are the boundary signs described in Paragraphs 6c and 6d necessary if a caution bar (three yellow in-pavement lights) is installed at the holding position marking?
Under the present standards, a caution bar located at a runway/taxiway holding position is bidirectional and would provide a pilot with the same information concerning the location of the holding position as the boundary sign does. However, based upon the work being done on the lighting requirements for low visibility, it appears that the caution bar standard will be changed so that the lights are unidirectional. In this case, the lights would be seen only by pilots entering the runway. Boundary signs are intended to provide information to pilots exiting the runway. Consequently, the decision on installing these boundary signs should not be based upon the absence or the presence of a caution bar.
14. Are all signs required to be installed on the left?
Paragraph 12a of the advisory circular states that signs shall always be installed on the left. Some exceptions are noted in Paragraph 12b for where it is physically impossible to place the sign on the left and in paragraph 12c for certain types of signs installed at certain locations. The reason for locating the signs on the left is that in many aircraft only the left seat cockpit position has access to the controls necessary for taxiing the aircraft.
15. Can "No Entry" signs be installed on the right side?
"No Entry" signs should be installed on left side as seen by the pilot approaching the prohibited area. In some pavement configurations, it may be necessary to install the sign on both the right and left sides. The sign should be located adjacent to the pavement that is not intended to be entered rather than prior to the intersection.
16. Is the use of the word "permissible" in Paragraph 12h intended to mean that the installation of the location sign is optional when the intersection is comprised of only one crossing taxiway?
The word "permissible" refers to the position of the location sign in the sign array. In an array of direction signs, the location sign is placed in the datum position, i.e., all direction signs indicating turns to the left are located to the left of the location sign and all direction signs indicating straight ahead or a turn to the right are located to the right of the location sign. Paragraph 12h allows the location sign to be placed to the left of the direction sign array when the intersection is comprised of only two taxiways. This type of installation eliminates the need for one sign panel. Either one of the following sign arrays would be acceptable for the intersection of taxiways A and B as seen from Taxiway A: Array with location sign in datum position <-B {A} B->;
Array with location sign on left {A} <-B->;
17. What is the requirement for lighting runway/runway intersection signs?
If either one of the runways is lighted, then the runway /runway intersection signs for both runways must be lighted. If both runways are unlighted, then the runway/runway signs need not be lighted.
18. Where are runway exit signs located relative to the exit?
Since these signs indicate a change in direction, i.e., a turn, they should be located prior to the exit. However, the advisory circular does not provide specific distances for the location of these signs because of the many variables that must be examined on a site specific basis. These variables include considerations such as speed at which the aircraft is expected to use the exit location, proximity of the previous exit, presence of taxiway centerline lights, and the "sea of blue" effect.
19. Is it permissible "to bracket" a runway exit with signs?
As used in the question "bracket" refers to the practice of installing a sign before the exit and another one after the exit. This practice is not permitted under the current standard. In the past, two applications were commonly used to bracket an exit. Both involved installing a taxiway designation sign prior to the exit. On the far side of the exit, a second sign was installed that either had an arrow by itself or a destination sign with an arrow. Neither of the signs on the far side of the exit are in accordance with the current standard and should be removed.
20. For taxiway/taxiway intersections, how far from the intersecting taxiway, should the direction and location sign array be located?
Paragraph 13 allows this sign array to be installed anywhere in the area between the point of tangency and the distance specified in Table 3 if there is no operational requirement for a taxiway holdline. When a taxiway holdline is necessary, the sign must be installed within ten feet of the marking (Table 3 distances). For new installations, it would be preferable to install the array in accordance with Table 3 even if there is not a current requirement for a taxiway holdline. Installation in this manner will avoid the need to relocate the array if an operational requirement for a holdline develops in the future.
21A. What is the advantage of a double face sign fixture over a single face fixture?
Some manufacturers make signs that allow a sign face to be installed on both the front and the back (double face) while others only make single face sign fixtures unless a double face sign is specifically requested. A number of signs are allowed to be installed on the back of other signs (see Paragraph 12c). Initially, the need for some of these signs may not be recognized. A double face sign fixture provides for the easy installation of these signs in the future by the acquisition of a face panel; in contrast, a single face sign fixture would have to be replaced with a double face one or an additional single face sign fixture would have to be installed.
SIGNS and MARKING SUPPLEMENT #2
November 29, 199121. If a taxiway intersects a blast pad or stopway, is it permissible to install a runway approach area holding position sign on the taxiway?
Change 1 to AC 150/5340-18C clarifies that Holding Position Signs for Runway Approach Areas should not be installed on taxiways that intersect the runway specified on the sign. A blast pad or stopway is never considered to be part of the runway. Therefore, it's proper to place a runway approach hold position sign on a taxiway that intersects a blast pad or stopway.
22. In SAMS #1, the answer to question #6 indicates that a dash should only be used on mandatory instruction signs. Isn't it permissible to use a dash on outbound destination signs when there is a common route to the two ends of a single runway?
In the situation described part of the taxiing route that is followed to get to either end of a runway is the same. From an airport design perspective, the tendency is to consider this single piece of pavement as one runway. However, from a pilot's perspective this single piece of runway is really two runways. Since the sign is intended to provide information to pilots, a dot should be used to separate the designations for each end of the runway. For example, a destination sign for a right turn on a taxiing route that is common to both ends of Runway 18-36 would look like:
18*36->;
23. The holding position sign for a runway/runway intersection is located at a place where the fillet for a high speed exit is contiguous to the runway. Because of the fillet the width of the pavement (runway plus fillet) is greater than 150 feet. Are holding position signs required to be install on both the left and right sides of the runway at this location?
The width of the pavement is irrelevant. What is important is the width of the runway. Locating the signs on both sides of the runway is not required unless the pavement width of the actual runway is greater than 150 feet. If the fillet is on the left side of the runway and the sign can not be installed in accordance with the installation tolerances in Table 2 of the advisory circular, it would be permissible to install this sign on the right side of the runway. The preceding answer assumes the runway is not used for "land, hold short" or taxiing operations.
24. When the holding position for the runway and ILS critical area are collocated, is it permissible to install both a runway holding position and ILS critical area holding position sign?
This situation is addressed in Figure 10(c) of the advisory circular. Only the runway holding position sign should be installed. Some may argue that placing an ILS sign at the holding position provides the pilot with additional information. However, this additional information could mislead the pilot into thinking that the regular holding position is closer to the runway and result in him/her taxiing past the point where they were supposed to hold. In this situation, the pavement marking for the holding position will be the standard four lines- two solid and two dashed.
25. On runway exits is it permissible to install at the holding position marking a runway safety area/OFZ sign on the right side of the exit taxiway and a direction sign for the parallel taxiway on the left side of the exit taxiway?
See Question 31 in SAMS #3.
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27. What signs should be installed at the intersection of a paved runway with a turf runway?
The advisory circular does not make any distinction between runway intersections based upon the runway surfaces. Therefore the standard runway/runway holding position signs should be installed as specified in Paragraph 5b.
28. On a taxiway, that is used only as an exit from a runway, is it permissible to install a "Do Not Enter" sign in lieu of the runway holding position sign?
All taxiways that provide ingress or egress to the runway are required to have the standard runway/taxiway holding position sign regardless of whether the taxiway is only used as an exit. It is also permissible to install a "Do Not Enter" sign on these taxiways; however, this sign may never be installed in lieu of the runway/taxiway holding position sign. In these situations the "Do Not Enter" sign should be installed on the taxiway prior to the holding position sign.
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30. It is our understanding that when Advisory Circular 150/5345- 44E is approved it will change the luminance requirements for airfield signs. Will existing signs that meet the specifications of Advisory Circular 150/5345-44D have to be replaced?
Advisory Circular 150/5345-44E which is scheduled to be approved early in December will change the luminance requirements for new airfield signs. However, existing signs that were installed in accordance with Advisory Circular 150/5345-44D standards do not need to be replaced provided that the sign face is either
- in accordance with Advisory Circular 150/5340-18C standards or
- the existing face can be replaced with a face meeting the standards of Advisory Circulars 150/5340-18C and 150/5345-44E.
SIGNS and MARKING SUPPLEMENT #3
December 24, 1991To: SAMS Users Question 25 and its answer that appeared in SAMS #2 should be deleted. It is replaced by Question #31. SAMS Editor
31. On runway exits is it acceptable to install at the holding position marking a runway safety area/OFZ sign on the right side of the exit taxiway and a direction sign for the parallel taxiway on the left side of the exit taxiway?
Having the boundary sign on the right and the direction sign on the left would conflict with Paragraph 12(a) of the advisory circular which requires sign faces located on both sides of the taxiway to have identical faces. However, in this particular case, it is acceptable to have nonidentical signs on the left and right sides of the taxiway. In accordance with Paragraph 12(c) of the advisory circular runway safety area/OFZ boundary sign may be installed on the reverse side of the runway holding position sign. This would place the boundary sign on the right side of the exit taxiway. If it is necessary to provide exiting aircraft with a direction sign located at the holding position marking, it would be located on the left side.
A formal change will be made to Paragraph 12a (requirement for identical signs on left and right sides of taxiways) of AC 150/5340-18C to clarify this point.
32. If an airport operator desires to place a sign on a taxiway to indicate a crossing vehicle roadway, what type of sign should be used?
Under the current standards that exist in AC 150/5340-18C this sign would be classified as an information sign and have a black inscription on a yellow background. The size and message of the sign would be left to the airport operator's discretion as long as there was adequate clearance between aircraft and the sign. However, care should be taken to ensure that the sign does not take on the appearance of a taxiway direction or destination sign.
33. At many airports the holding position sign for an intersecting runway was located 500 feet from the intersecting runway centerline. Table 1 of AC 150/5340-18C allows these signs to be located anywhere from 125 feet to 280 feet from the intersecting centerline. Is it necessary to relocate the existing signs to the Table 1 distances?
The distances specified in Table 1 are minimum distances. For this reason, it is not necessary to relocate existing signs solely because they are placed at a distance greater than that specified in Table 1. However, there are some operational considerations that may make it desirable to relocate these signs to the specified minimums. For example, leaving the sign at the greater distance reduces the length of runway available for "land, hold short" operations. Similarly, if there is a parallel taxiway for the intersecting runway, the location of the holding position sign and runway exit sign (for the parallel) in proximity to one another could lead to confusion.
34. Is it acceptable to use a color other than yellow to provide taxiing guidance on the movement area?
The standard color for marking taxiways is yellow (see Paragraph 7 of AC 150/5340-1F.) Over the years some airports have installed other colors to denote various taxiing routes on the movement areas. These markings are nonstandard. In an attempt to circumvent the standard, these different colored markings have sometimes been referred to as supplemental markings or some other ambiguous term. Regardless of what they are called, these markings are nonstandard and require specific approval by the Director of the Office of Airport Safety and Standards.
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36. The setback distances for the holding position markings that are contained in AC 150/5340-18C and Change 1 to AC 150/5340- 1F differ from those that appeared in AC 150/5340-1F. In some cases, the new standards would require relocating the hold position marking from 1 to 32 feet further back than the former standard? Are these greater distances justified?
This situation is currently being reviewed to see what leeway, if any, can be provided. In the interim, holding position markings and their associated signs that were located in accordance with the former criteria in AC 150/5340-1F and where there has not been a change in aircraft category or design group should not be relocated.
37. What should the airport operator consider in deciding when to implement revised taxiway designations?
The Application paragraph of AC 150/5340-18C, standards for Airfield Sign Systems recognizes that redesignation of taxiways in accordance with the advisory circular standards could cause confusion and operational safety problems for the users. For this reason, the advisory circular recommends that the airport operator develop an implementation plan for making these changes. The following should be considered in developing the implementation plan.
Parties to be coordinated with
:- air traffic control tower
- airlines serving the airport
- fixed based operators
- corporate users
- vehicle operators authorized to drive on affected taxiways such as operations, maintenance, and ARFF employees of airport operator
- tenant employees
- FAA technicians
- individuals involved in construction which requires them to travel, cross, or work in vicinity of affected taxiways
- mutual aid organizations
Training Coordination should determine population within each of the above groups which would be affected by the change and the time necessary to train each of those populations in the new designations. This time will vary depending upon the extent of the change (e.g., redesignating an entire airport vs. one or two taxiways), the type of group, and location of each group (i.e., is each population based on the airport?) Chart Updates As part of the coordination the airport operator should determine how quickly each of the affected parties could update the charts they use for ground movement on the airfield. In some cases, these parties (e.g.,vehicle operators) may be dependent upon airport diagrams furnished by the airport operator.
Others such as the airlines subscribe to charts that are published by Jeppesen-Sanderson. These charts are updated every two weeks with a requirement to submit changes two weeks prior to the publication date. Changes in taxiway designations may be submitted directly by the airport operator, or through the airline or Air Transport Association of America to Jeppesen-Sanderson.
Many users in the general aviation community use airport diagrams developed by the U.S. Government and published by NOS. These diagrams are published every 56 days. Changes to be included in the next publication date must be submitted by the air traffic tower manager at least five weeks prior to the that date ( see Order 7910.4B, Airport Diagrams.)
Whenever possible, the changes should be made so that it coincides with an established publication cycle. Signs Signs corresponding with the changed designations should be in place at the time or within a few days of the change (if it is not feasible to make all the sign changes at one time.) Likewise, signs with the former designations should be removed or covered.
User Notification A letter should be sent to each of the coordinated parties formally notifying them of the changes and the planned implementation date. The implementation date should allow sufficient time for the users to provide necessary training and update their charts. A NOTAM should be issued informing pilots of the change in taxiway designations. The Air Traffic Control Tower should be requested to place a general statement on the ATIS advising pilots that taxiway nomenclature has changed. The tower may also want to consider issuing a letter to airmen.
SIGNS and MARKING SUPPLEMENT #4
January 28, 199238. Paragraph 9a of AC 150/5340-18C discusses the use of the "dot" in conjunction with outbound destination signs and shows an illustration of this application in Figure 18. Is it acceptable to use the "dot" in conjunction with two inbound destinations?
Reference the answer to SAMS #1, Question 6. Since the "dot" on a sign face means "and," it may be used on a sign face where any two destinations have a common direction at the point where the sign is located. The arrow which would be located on the sign face would be applicable to both destinations. Consequently, where the circumstances warrant, a "dot" could be used in conjunction with two outbound destinations, two inbound destinations, or even in some cases, an outbound and inbound destination when the destinations have a common direction. In this regard, the "dot" may be used between more than two destinations on a sign face provided that all the destinations separated by a "dot" have a common direction.
39. Paragraph 12b(5) of AC 150/5340-18C states that destination signs on the far side of an intersection can be placed on the right side (i.e., on the back of a direction sign) when the destination is straight ahead. If a runway safety area/OFZ boundary sign is not needed, can a destination sign be placed on the back of a mandatory runway holding position sign?
A destination sign could be located on the right side of a taxiway on the back of a holding position sign provided that:
- the destination is straight ahead,
- a taxiway direction sign is not located on the left side of the holding position, and
- it's determined that the runway safety area/OFZ boundary sign is not needed.
40. At small airports is it acceptable to install taxiway direction signs on the reverse side of runway holding position signs?
Major emphasis in the implementation of the AC 150/5340-18C standards is being placed on achieving uniformity between airports. Installation of taxiway guidance signs on the reverse side of runway holding position signs is not acceptable since it would place the sign on the right side of the taxiway. Paragraph 12 of the AC specifies that signs should be installed on the left unless otherwise noted. Paragraph 12c specifically identifies the signs that may be installed on the reverse side of another sign, thereby placing them on the right. Taxiway direction signs are not identified for installation in this manner.
41. It is our understanding that a change is going to be made to FAR Part 139 to require runway distance remaining signs on runways served by air carrier turbojet aircraft. Paragraph 23 of AC 150/5340-18C states that these signs should be designed so that they are illuminated whenever the runway lights are illuminated. The standards for these signs contained in AC 150/5340-44E only provides for lighted signs. Is it intended to require these signs be lighted on unlighted runways?
A definitive answer cannot be provided until the rulemaking referred to in the question is completed. At this time the FAA is on record that it will issue a Notice of Proposed Rulemaking (NPRM) to Part 139 which would require runway distance remaining signs. The details of this NPRM have not been finalized. It is unlikely that the NPRM would require lighted signs on an unlighted runway. Once the NPRM is issued, any comments received in response to it will be evaluated and considered in developing the final rule.
42. The response to Question 19 in SAMS #1 states that signs may no longer be used "to bracket" a runway exit. Paragraph 4 of AC 150/5340-24, Runway and Taxiway Edge Lighting System, states that signs are used to define the throat or entrance into the exit taxiway unless they would interfere with aircraft operations. The guidance in the SAMS appears to be contrary to AC 150/5340-24. Which is correct?
The guidance in these two documents is in conflict if you interpret the word "define" as used in AC 150/5340-24 to mean that the signs must delineate both sides of the exit. However, "define" could also be interpreted to mean that a sign must be installed to identify the location of the exit taxiway. With AC 150/5340-18C and the SAMS, we consider the latter interpretation to be the correct one so no conflict exists. When AC 150/5340-24 is updated this point will be clarified.
Perhaps some further background on the development of AC 150/5340-18C standards would be helpful. One of the underlying principles of these standards is that any sign that indicates a change in direction must be located prior to the intersection. The practice of "bracketing" an intersection places a sign indicating a change in direction on the far side of the intersection. Adequate delineation of the boundaries of the exit taxiway is already provided by the pavement markings, lights, and pavement and it was believed that this additional sign may give the false impression that an additional exit exists beyond it.
43. Paragraph 4 of AC 150/5340-24 indicates that two taxiway lights may be installed on the point of tangency of the taxiway exit and runway instead of a sign when the sign would interfere with aircraft operations or at small general utility airports. Is this practice still acceptable?
In accordance with Paragraph 3e of AC 150/5340-18C a runway exit sign should be installed along each runway for each normally used runway exit. This is applicable to all airports regardless of their size. (Note: Paragraph 3f allows a destination sign to be used in lieu of the runway exit sign at uncontrolled airports.) In view of the flexibility that is allowed in the placement of this sign, we can not envision a situation where the sign could not be installed due to a conflict with aircraft operations. The guidance contained in AC 150/5340-24 will be updated to be consistent with AC 150/5340-18C. At that time the benefit of the two taxiway lights located at the point of tangency will be reevaluated.
44. Heretofore, taxiway location signs have been black letters on a yellow background. AC 150/5340-18C specifies these signs should have yellow letters on a black background. Will all the black on yellow signs require replacing and, if so, when?
At airports certificated under FAR Part 139, all signs are expected to be in compliance with the standards set forth in AC 150/5340-18C by January 1, 1994. At other airports compliance with the new standards is encouraged to take place as soon as possible. Consequently, signs not having the correct color combinations would have to be replaced. (See SAMS #1, Questions 2 through 6 for additional information.) For historical purposes, it is worth mentioning that the underlying premise of this question is incorrect. Prior to the issuance of AC 150/5340-18C, the FAA sign standards had no provision for identifying the taxiway on which an aircraft was located.
45. Paragraph 9b of AC 150/5340-18C provides typical sign inscriptions for inbound destination signs. In the past, abbreviations such as "RMP" for RAMP has been used as this reduced the typical guidance sign by one module and resulted in a cost savings. Are abbreviations such as "RMP" for RAMP, "APRN" for APRON, "CRGO" for CARGO, and "FRT" for FREIGHT acceptable?
Paragraph 9b stipulates that the inscription for inbound destination signs contain at least three letters which should be selected so that no confusion could exist with other taxiway guidance signs. The inscriptions listed in that paragraph are referred to as common abbreviations. However, they are by no means the only acceptable inscriptions. In selecting an inscription to use, it's important to keep in mind that the purpose of the sign is to help the pilot taxi to his intended destination. Consequently, any inscription selected should be readily understood by pilots who use the airport. For example, a sign inscription "APRN" may be readily understood at an airport serving only domestic traffic while a sign with the inscription "APRON" may be more appropriate at airport serving international traffic. Comprehension of the intended sign message and not the fact that one inscription may require an additional sign panel over another should be the overriding consideration in determining the sign inscription. See SAMS #1, Question 5 regarding the consistent use of inscriptions on an airport.
With regard to the specific terms cited in the question, we believe that the abbreviations "RMP," "APRN," and "CRGO" may be sufficient on many airports. However, we believe most pilots would have difficulty interpreting "FRT" to mean FREIGHT.
46. Some runways have a turnaround constructed at their ends in lieu of a parallel taxiway. Is it necessary to designate the turnaround and install signs?
Turnarounds are usually located on runways that do not have a high level of activity. They have two common configurations: a rectangular pad appended to the side of the runway which is illustrated in Figure 4-9 of AC 150/5300-13, Airport Design, and the configuration (or variation thereof) illustrated in the figure below. Normally, it is unnecessary to install runway exit signs for these turnarounds and/or designate these pavement areas.
However, standard runway holding position signs and markings should be installed on these turnarounds.
There are two situations where the installation of the runway exit signs for turnarounds should be considered.
- the airport has an air traffic control tower and controllers instruct pilots to exit the runway onto the turnaround, or
- the runway is regularly used at night or in reduced visibility conditions and pilots have difficulty discerning the location of the turnaround.
In either of the above situations, if a decision is made to install a runway exit sign for a turnaround of the rectangular pad type configuration, consideration should also be given to installing taxiway ending markers around the pad. These markers will confirm to the pilot that he/she is on a turnaround rather than a taxiway.
47. Is it necessary to replace the entire sign face of an existing sign that does not meet AC 150/5340-18C if compliance can be achieved by replacing only one panel of the existing face?
Although it would be acceptable to replace just one panel of an existing sign face to bring it into compliance with the AC 150/5340-18C requirements, it is difficult to match the colors (because of weathering), borders, etc. of the remaining panels. In some cases, these differences can be so significant that it is distracting. In these cases, it would be advisable to replace the whole sign.
48. Figure 8b of AC 150/5340-18C shows an example of a canted holding position sign on the right side of the taxiway accompanied by a holding position sign located on the left side of the taxiway. Is it a requirement to install signs on both sides of the taxiway when one of the signs is canted?
The purpose of canting the sign is to improve its visibility to the pilot. Two signs are included in Figure 8b because the holding position marking on the stub taxiway is located so close to the edge of the parallel taxiway that the pilot of a large aircraft would have difficulty seeing the sign on the left. In this case the sign is also installed on the left for pilots of smaller aircraft. The decision to install the second sign is not based upon whether a sign is canted. The figure below provides an example where only one sign is installed and it is canted to improve its visibility.
49. When all the available letters for taxiway designations are used at an airport, why is it unacceptable to use alphanumerics rather than double letters for designating the remaining taxiways?
In accordance with Paragraph 4c of AC 150/5340-18C, alphanumeric designations should only be used for stub taxiways that are connected with a major taxiway. When used the alpha part of alphanumeric should correspond to the alpha designation for the major taxiway. For example, the stub taxiways connecting a parallel taxiway Bravo with a runway could be designated as B1, B2, B3, etc. An alphanumeric designation where the alpha part does not refer to the major taxiway designation should not be used. In the preceding example, it would be improper to designate the stubs as T1, T2, T3, etc. when the parallel taxiway is designated as Bravo.
It is acceptable to continue the alphanumeric designation beyond the parallel to the next taxiway or runway. If the taxiway continues in either direction beyond that point, it should have an alpha designation.
This coding system allows a pilot to identify readily stub taxiways from through taxiways. From a human factors perspective, using alphanumerics on taxiways that are not stubs will negate this coding system and, for this reason, is unacceptable.
50. What coordination is necessary prior to the installation of holding position markings on runways at runway/runway intersections?
On airports with air traffic control towers, airport operators should notify the tower manager prior to installing the markings. As part of the notification, the airport operator should provide the distances measured along the runway centerline from the threshold to the holding position marking. This distance will be used by the tower as the runway length available for "Land, Hold Short" operations and will be published in the Airport/Facility Directory.
51. CANCELLED
52. Why are airport operators being asked to defer painting the holding position markings for runway/runway intersections until after June 25, 1992?
The delay was requested by Air Traffic so that they could make the necessary changes in their directives to accommodate these markings in their procedures. If the painting schedules preclude deferring the painting until after the June 25 date, airport operators should contact the air traffic control tower manager and the regional airport certification inspector so procedures can be instituted to assure the safety of the operation.
SIGNS and MARKING SUPPLEMENT #5
February 20, 199253. Although Advisory Circular 150/5345-44E, Specification for Taxiway and Runway Signs was approved on December 16, 1991, signs meeting these specifications are unavailable. Is it acceptable to use the former specifications in Advisory Circular 150/5345-44D for the procurement of new signs to be installed on airports until signs meeting the new specifications become available?
Signs manufactured in accordance with the AC 150/5345-44E specifications have several advantages over the ones manufactured under the AC 150/5345-44D specifications in the areas of luminance, wind loading, and message readability. For this reason, it would be prudent to delay contracting for new signs until the ones meeting the AC 150/5345-44E specifications become available. It is expected that some manufacturers will have these signs available in April.
We recognize that, in some cases, it may not be possible to delay contracting for signs until the AC 150/5340-44E signs become available. In this case, the signs manufactured in accordance with AC 150/5345-44D specifications would be acceptable; however, the sign face should meet legend specifications, i.e., color, spacing between characters, spacing to sign edge, arrows, dots, dashes, and message dividers, specified in AC 150/5345-44E. This is particularly important if the sign face has more than one message, e.g., a location sign and holding position sign or a directional sign array.
The list of advisory circulars that appears in the grant assurances (Assurance 34) will be updated no later than June 16, 1992 to reflect AC 150/5345-44E specifications. The assurances will be updated earlier if, as currently expected, manufacturers receive approval for their signs in April. All signs contracted for under the updated assurances will be expected to meet the AC 150/5345-44E specifications.
Note: Question 30 in SAMS #2 addresses the need to replace the sign faces on existing signs that meet AC 150/5345-44D standards.
54. A holding position on a taxiway is applicable to runway 9-27 and the runway 34 approach. Should the sign for this holding position have the inscription "9-27*34-APCH?"
The purpose of the runway approach holding position sign is to provide a reference (when no other one is available) for both the pilot and controller to use when it is necessary to hold short of a runway approach area. Consequently, the approach holding position sign should not be used in an array with another runway holding position sign. When the holding position for the approach to one runway is the same as the holding position for another runway then only the latter should be inscribed on the sign. In the case described, the sign inscription would be "9-27."
55. The response to SAMS #1, Question 1 could be interpreted to mean that an airport that currently has taxiways designated with letters does not need to consider redesignating these taxiways so that the letters are consecutive. Is this the intended interpretation?
In accordance with Paragraph 12b of AC 150/5340-18C, the designations for taxiways should optimally start at one end of the airport and continue to the other. Any airport operator that does not have its taxiways designated in this manner should consider and is encouraged to redesignate them to meet this optimum. The response to SAMS #1, Question 1 addressed situations where the FAA would require an airport to redesignate taxiways that did not comply with the standards. In this regard, the FAA does not intend to require an airport operator that currently designates its taxiways with letters to redesignate the taxiways so that the letters will be consecutive from one end of the airport to the other.
56. The response in SAMS #4, Question 45 indicated that the inscriptions other than those listed in Paragraph 9b of AC 150/5340-18C may be acceptable for inbound destination signs. In view of this response would you please clarify the status of the inscriptions listed in that paragraph?
Paragraph 9b lists inscriptions for common destinations on airports. Although the inscriptions listed are not the only ones that may be acceptable, they should be considered as the preferred inscriptions for those destinations.
SIGNS and MARKING SUPPLEMENT #6
March 31, 199257. At a Tee intersection formed by two taxiways (where Alpha is the stem of the Tee and Bravo is the top of the Tee), how should the location and direction signs be arranged on Bravo for a left turn onto Alpha?
The sign array should be located on the left side of Bravo and read as follows: <-A {B}
The exception provided for in Paragraph 12h of AC 150/5340-18C (convention of placing location sign on left when the intersection is comprised of two taxiways) was intended to be used only when the intersection was comprised of two crossing taxiways.
58. Paragraph 10, Roadway Signs, of AC 150/5340-18C only provides for stop and yield signs. Does this mean that any other sign located along airfield vehicle roadways is considered to be an information sign under the provisions of Paragraph 11?
Signs located on the airfield that are solely intended for vehicle operators should conform to the categorical color codes established by the Manual on Uniform Traffic Control Devices. The location, size, and installation criteria may have to be varied from the preceding manual so that they do not conflict with the airfield environment, e.g.,wing tip clearances. As used in the advisory circular, information signs were intended to be signs directed at pilots although they may also be applicable to vehicle operators.
59. Paragraph 12a of AC 150/5340-18C states that signs should not be installed between the holding position on the taxiway and the runway. Does this mean that a sign directed at aircraft exiting the runway can not be located in this area?
The provision in Paragraph 12a was included because it was believed that any sign located between the hold position and the runway may divert the pilot's attention from the hold position and result in a runway incursion. However, it was intended only to apply to sign faces directed to the pilot at the holding position. It would be acceptable to install a sign with a legend directed toward the runway and a blank side facing the hold position in this area.
60. Is it acceptable to install destination signs that the pilot could see at the same time that indicate two different directions to the same destination?
Signs indicating two different directions to the same destination should not be installed so that they are visible from the same point since the conflicting routing information can create confusion. This situation commonly occurs with destination signs to the takeoff runway. In some cases, one of the signs directs the pilot to the beginning of the takeoff runway while the other sign directs the pilot to some intermediate point on that runway. In this instance, the destination sign should always direct the pilot to the beginning of the takeoff runway.
61. When it is necessary to use two separate signs in a sign array, what requirements apply with regard to such things as sign length, spacing, etc.?
These requirements can be found in Paragraph 3.3.1 of AC 150/5345-44E. Some of the requirements contained in this paragraph include the distance between the signs (3 to 12 inches), each sign is required to contain complete message elements, and limitations on the overall length of individual signs.
SIGNS and MARKING SUPPLEMENT #7
April 30, 199262. Should runway safety area/OFZ boundary signs be installed on both sides of a taxiway when the taxiway is 150 feet or greater in width?
To improve their visibility, AC 150/5340-18C indicates that holding position signs should be placed on both sides of the taxiway when the taxiway is 150 feet or greater in length. If it is determined that runway safety area/OFZ boundary signs are needed on a taxiway the same principle would apply, i.e., these signs should be installed on both sides of the taxiway when the taxiway is 150 feet or greater in width. The signs shown for taxiway Bravo in Figure 3 of AC 150/5340-18C will be corrected to depict this situation.
63. If an existing sign is extended to meet the requirements of AC 150/5340-18C, what specification requirements apply to the extension?
To extend an existing sign (i.e., physically increase its length by adding modules to it) all of the following requirements must be met:
- a. the existing sign must have met the AC 150/5345-44D specifications,
- b. the extension can not be longer than the original sign length nor can more than two modules be added to an existing sign,
- c. the overall length of the sign (existing plus extension) cannot exceed the length limitations provided in Table 1 of AC 150/5345-44E,
- d. unless the extension involves the addition of only a location sign, the sign face (existing plus extension) must meet the AC 150/5345-44E requirements with regard to legend, borders, arrows, spacing, and color, and
- e. the extension meets the electrical and frangibility requirements of AC 150/5345-44D.
64. The response to Question 36 in SAMS #3 indicated that the setback distances for holding position markings that were included in AC 150/5340-18C and Change 1 to AC 150/5340-1F were being reviewed to see if the increases over the distances that were originally in AC 150/5340-1F were justified. Has any determination been made?
An analysis based upon operational data from the ICAO Collision Risk Model revealed that the criteria contained in the original AC 150/5340-1F would be sufficient. This AC is currently being revised to include the table that appears below. This table will also replace Table 1 in AC 150/5340-18C. Until the revisions are made to these AC's the information in the following table should be used for determining the location of hold position markings.
Table 1. Location of holding position markings for taxiway/runway and runway/runway intersections
| Aircraft approach category and (airplane design group) | Perpendicular distance from runway centerline to intersecting taxiway/runway centerline in feet (meters) (1) | |
|---|---|---|
| Visual and Nonprecision Instrument | Precision Instrument (2) | |
| A & B (I & II) small airplanes only | 125 (38) | >175 (53) |
| A & B (I, II, III) | >200 (60) | >250 (75) |
| A & B (IV) | >250 (75) | >250 (75) |
| C & D (I through IV) | >250 (75) | >250 (75) |
| C & D (V) | >250 (75) | >280 (85) |
1. Increases for elevation above sea level are:
- a. Aircraft approach categories A &; B (Airplane design group III and IV). For precision instrument runways this distance is increased one foot for each 100 feet of airport elevation above 6,000 feet.
- b. Aircraft approach category C (Airplane design group III and IV). For precision instrument runways this distance is increased one foot for each 100 feet of airport elevation above 3200 feet.
- c. Aircraft approach category C (Airplane design group V). For all types of runways, this distance is increased one foot for each 100 feet of airport elevation above sea level.
- d. Aircraft approach category D (Airplane design groups I through V). For all types of runways, this distance is increased one foot for each 100 feet of airport elevation above sea level.
2. When a taxiway or runway intersects a precision instrument runway at an angle of less than 45 degrees, it is necessary to increase the distances in this column if any part of the critical aircraft would penetrate the obstacle free zone.
65. Table 1 of AC 150/5340-18C provides location distances for holding position markings. Is this a misprint? Are the distances in this table really suppose to be the location distances for the hold position sign?
This table is correctly labelled. Hold position signs are located in line with the holding markings; a tolerance of +/- 10 feet is allowed. When the two pavements cross at a right angle the distance to the marking will be the same as the distance to the sign; however, when the pavements intersect at less than 90 degrees the distance to the markings and the sign will differ since the holding position marking is located perpendicular to the pavement centerline.
66. At the intersection of three runways is it necessary to have arrows on the red and white runway/runway holding position signs?
Arrows are necessary on these signs only if the runways are normally used for taxiing aircraft. If a taxiway intersected the intersection of three runways, the holding position signs on the taxiway would show all three runways with arrows indicating their respective alignments.
67. When a runway intersects another runway at its end, e.g., a T, V, or Y intersection, is it acceptable to have only one runway designation on the runway/runway holding position sign?
The same rules that would be applicable to a taxiway intersecting the takeoff end of a runway would apply; therefore it would be acceptable to have one designation for the runway that ends at the intersection.
68. CANCELLED
69. Will any additional signs be required to conduct operations in low visibility conditions? The FAA has not finalized the requirements for operations in low visibility. At this time, it appears that signs in addition those necessary for operations in good weather will be limited to runway safety area/OFZ boundary signs for taxiways providing egress from the low visibility runway and signs for points used for reporting geographic position when the point is not already readily identifiable. At this time, a standard has not been developed for these latter signs and it's possible that the sign may actually be painted on the pavement rather than installed along side of it.
In determining what signs to install along low visibility taxiing routes, one has to remember that the availability of other visual cues is limited. For this reason, consideration should be given to installing location signs on the far side of the intersection whenever a turn is required to provide confirmation that the pilot has made the correct turn (See Figure 21, AC 150/5340-18C). Also consideration should be given to using the standard direction and location sign array rather than the optional one provided for in Paragraph 12h of AC 150/5340-18C if a turn is required and the two pavements cross at other than a right angle.
SIGNS and MARKING SUPPLEMENT #8
May 29, 199270. If lights are installed on a runway but not on the exit taxiways associated with it, do the signs for the runway exits installed along the runway need to be lighted?
The information in AC 150/5340-18C could be interpreted two different ways. In Paragraph 4d of the signature page, it states that signs should be lighted if the runway or taxiway on which they are installed is lighted. Under this paragraph exit signs installed on a lighted runway would also be lighted. However, Paragraph 14 of the same AC does not identify runway exit signs as one of the signs that should be illuminated when the runway is illuminated. This paragraph further states that "other taxiway guidance signs should be illuminated when the associated taxiway is illuminated." One could infer from this latter statement that if lights are not installed on an exit taxiway then there is no need to light the exit sign on the runway.
Paragraph 4d was intended to provide guidance for installation of signs while Paragraph 14 was intended to provide guidance on sign operation which would be helpful in determining the electrical circuit/control system designs.
To clarify this matter, runway exit signs should be lighted if the runway on which they are located is lighted and the associated exit taxiway is lighted or has either edge or centerline reflectors.
71. A taxiway crosses one runway then, after a short distance, crosses another runway. The section of taxiway located between the two runways is not long enough to locate holding position markings and signs at the standard setbacks from each runway centerline. In this situation would it be acceptable to install holding position signs for both runways at the holding position located prior to crossing the first runway?
In this situation holding position signs for the two runways should not be installed beside each other on the taxiway since it gives the impression that the taxiway actually intersects the intersection of the two runways.
Determining what signs would be needed in this situation can be made only after evaluating the functional layout of the individual airport. For example, if the airport has a 24 hour control tower it may be possible to take care of this situation through procedures. In other cases, it may be acceptable to obtain a deviation from the standard holding position setbacks and locate holding positions on the section of taxiway located between the two runways. It may also be possible to resolve the situation by restricting the type of aircraft which may use the taxiway. Another option which may be applicable at some airports is to close the section of taxiway located between the two runways.
Other options and combinations of options may exist depending upon the situation at the individual airport. Also consideration should be given to installing location signs on the runways if the taxiway is used for intersection departures.
72. Some existing runway holding position signs are 68 inches in length. Can a Runway Safety Area/OFZ boundary sign be installed on the back of one of these 68 inch signs?
This question is prompted by the specifications in AC 150/5345-44E that states runway safety area/OFZ signs are 84 inches in length. Assuming that the back of the holding position sign would accommodate the panel for the runway safety area/OFZ sign, it would be acceptable to proportionally reduce the length of the legend of this sign to 68 inches from 84 inches.
SIGNS and MARKING SUPPLEMENT #9
July 29, 1992Does Your Sign Plan Have Too Many Signs?
Based upon the review of several sign plans, it appears that the concept of functional layout (see Paragraph 2 of AC 150/5340-18C) is being ignored in the preparation of many of these plans. The result is the inclusion of several taxiway directional and destination signs of questionable value on these plans. There is a tendency to include a direction sign for every leg of every intersection even though a pilot would not normally make a turn onto those legs. Also it seems that destination signs are being overused on controlled airports. The additional signs increase costs initially (i.e., cost of sign, cost to upgrade electrical system), as well as operationally over the life of the sign. More importantly, too many signs can cause confusion rather than clarification of routing information.
Appendix 1 was included in AC 150/5340-18C to illustrate the use of functional layout in determining what signs were needed for three hypothetical airport situations. It is important to recognize that the sign systems shown in this Appendix are not the only acceptable solutions for these three situations. Therefore, it is incorrect to infer that if an airport has a similar configuration to one of those shown in the Appendix, its sign plan should be the same as that shown in the Appendix.
In summary, the need for each taxiway direction and destination sign at a particular airport should be determined based upon the functional layout of the individual airport.
Common Mistakes On Sign Plans
Our regional personnel involved in the review of sign plans report that they see the following mistakes on a regular basis:
- proposing direction signs on the back of holding position signs thereby placing direction sign on right rather than left side of taxiway. Note: A common explanation is that doing this saves a sign fixture. The standard is explicit that these signs should be on the left. In most cases, being aware of oversigning will save more sign fixtures.
- proposing destination signs in arrays with location signs or taxiway direction signs. Destination signs should never be collocated with any other signs (see paragraph 12j of AC 150/5340-18C.)
- improper placement of location sign in taxiway direction sign array. Except for a simple intersection (see paragraph 12h of AC 150/5340-18C) the location sign should always be placed in these arrays so that all signs indicating turns to the left are on the left side of the location sign and all signs indicating turns to the right or straight ahead should be to the right of the location sign.
- improper location of holding position lines.
- failure to properly identify and sign runways used for "Land, Hold Short" operations.
73. Can other signs be collocated with the ILS critical area hold position sign?
The ILS critical area hold position sign will generally be located by itself. It is acceptable to collocate a taxiway location sign with it. However, direction and destination signs should not be collated with the ILS critical area hold position sign.
74. Paragraph 14 of AC 150/5340-18C states that holding position signs should be illuminated when the lights of the associated runway are illuminated. Does this mean that the holding position signs must be on the same electrical circuit as the runway lights?
There is no requirement that the holding position signs be on the same circuit as the runway lights. The requirement in Paragraph 14 could be accomplished through a procedural means. For example, if the holding position lights were on the same circuit as the taxiway lights, procedures would have to be established to assure the taxiway lights and holding position signs were illuminated whenever the runway lights were illuminated.
75. Is there any requirement for an airport operator to delineate the boundaries of the Security Identification Display Area (SIDA) by marking or lighting?
Under FAR Part 107, the operators of certain airports are required to designate areas where all unescorted personnel must display their airport identification badges at all times. This area is known as the SIDA.
Some confusion existed as to whether or not the boundaries of the SIDA had to be physically delineated with markings or lights. The Office of Civil Aviation Security Policy and Planning has informed us that there is no existing or anticipated requirement to mark or light this area. If a need later arises to mark this area, draft standards will be developed and coordinated with the industry before a final standard is adopted.
If an airport operator desires for their own purposes to delineate the SIDA on their airport, the proposed marking should be coordinated with the FAA regional airports and security offices that have jurisdiction over the airport.
SIGNS and MARKING SUPPLEMENT #10
November 16, 199276. On airports certificated under Part 139 when are the signs and markings associated with a "Land, Hold Short" operation required to be installed?
Before examining the compliance dates, a review of the sign and marking standards for this situation is appropriate. In accordance with Paragraph 5b of Advisory Circular 150/5340-18C, runways used for "land, hold short" operations should have holding position signs installed on both the left and right sides of the runway. Standards contained in Paragraph 9f of Advisory Circular 150/5340-1F, Change 1, specify a holding position marking (two dashed lines and two solid lines) be installed across the width of the runway. Airports certificated under Part 139 were required to have had a holding position sign installed on the left side of the runway prior to the intersection with another runway by January 1, 1991. The holding position markings on runways at these airports were supposed to be installed by October 1, 1992. The sign on the right side should be installed as soon as possible, but no later than January 1, 1994.
77. The holding position for a "land, hold short" operation is located at a place where the fillet for an exit is contiguous to the runway. Because of the fillet the width of the pavement (runway plus fillet) is greater than 150 feet. How should the holding position signs and marking be installed on this runway?
This question is a follow up to question #23 in SAMS #2. The "land, hold short" operation requires a holding position marking on the runway and signs on both the left and right sides of the runway. Table 1 of AC 150/5340-1F as modified by the answer to question #64 in SAMS #7 provides the minimum distance the holding position sign should be located from the intersecting runway. The hold position marking should only extend across the width of the runway, i.e., it should not be extended across contiguous fillets or shoulders. The signs should be located on the left and right sides of the runway in line with the holding position marking. Table 2 of AC 150/5340-18C provides the distances that these signs may be located from the runway edge. If locating the sign at these distances would place the sign in the paved fillet or provide inadequate wingtip or engine clearance then the following three options or combinations thereof, are available: 1. the standards allow a ten feet tolerance on the location of the signs; thus the signs could be moved ten feet closer to or further away from the runway that is being held short of. 2. a larger size sign could be used since Table 2 allows these signs to be installed at a greater distance from the runway edge. (Note: This option is not applicable if a Size 3 sign is already being used.) 3. locate the holding position further away from the runway being held short of. This will shorten the length of runway available for the "land, hold short" operation and may preclude some aircraft from being able to perform that operation.
78.
A taxiway that is 75 feet in width only requires a holding position on the left side at its intersection with a runway. However, a runway that is 75 feet in width and regularly used as a taxiway is required to have holding position signs located on both the left and right side at its intersection with another runway. This appears to be a discrepancy. In the development of this paragraph 9b of AC 150/4340-18C, the working group was focusing on taxiing operations occurring on runways with widths of 150 feet or more. For runways less than this width that are used for taxiing, a sign is needed only on the left side. The AC will be changed to reflect this. However, if the runway regardless of its width is used for "land, hold short" operations then signs are still required to be installed on both the left and right sides.
79.
An airport has intersecting runways. If only a section of one of the runways is regularly used as a taxiway and that section does not include the runway/runway intersection, is it still necessary to install the holding position markings and signs at the intersection. Holding position markings and signs at runways regularly used as taxiways are required at runway/runway intersections only if the intersection is included in the section of the runway that is used as the taxiway. If the intersection is located outside the section of runway used as a taxiway, then only the standard runway/runway holding position sign on the left side is necessary.
80. The standards contained in Paragraph 5d of AC 150/5340-18C prohibit the use of the holding position signs for runway approaches from being used on a runway. Are there not some situations that would warrant the installation of this type of sign on a runway?
When the sign standards were developed, various users expressed concern that routinely installing this sign on a runway would confuse pilots. In response to those concerns, the prohibition was included in the standard. As airport operators developed sign plans, some situations were identified where air traffic control needed to stop an aircraft on a runway from interfering with an aircraft operating on a nonintersecting runway. Generally, these involved airports that had a minimal taxiway system and utilized the runways for taxiing. In these cases, it was determined that the use of the runway approach holding position sign on the runway was warranted. The advisory circular will be changed accordingly.
81. CANCELLED
82. Paragraph 12g of AC 150/5340-18C states that arrows on direction signs should be oriented to approximate the direction of the turn. How accurate should these approximations be?
The joint FAA/industry working group that developed the sign standards decided that they did not want to state a specific accuracy level; thus the wording "oriented to approximate the direction the turn." From a manufacturing perspective the arrow can be oriented to any angle specified. Generally, orienting the arrows in increments of 22.5 degrees, i.e., 0, 22.5, 45, 67.5, and 90 degrees, should be sufficient for most signs. A check with some sign manufacturers indicated that the majority of the orders that they received have not specified any particular angle for the arrows. The manufacturers are working from specifications that will show the arrow as vertical, horizontal, or angled. Consequently, lacking any specific angle information the arrows on signs are being placed at 0, 45, or 90 degrees. This can be somewhat misleading. For example, if a turn onto a taxiway requires a 75 degree turn, unless directed otherwise, the manufacturer will probably orient the arrow at 45 degrees. For this reason it is extremely important that the angle of the arrow on the sign be specified when the sign specifications for a particular project are developed.
SIGNS and MARKING SUPPLEMENT #11
January 31, 1994With issuance of AC 150/5340-1G, Standards for Airport Marking and Change 1 to AC 150/5340-18C, Standards for Airport Sign Systems, the following items in each SAMS are cancelled:
SAMS 1; #8 SAMS 2; #26, #29 SAMS 3; #35 SAMS 4; #51 SAMS 7; #68 SAMS 10; #81
83. Like all ACs initially published, there are several corrections to AC 150/5340-1G, Standards for Airport Markings, which will be made when the first change is issued, but which should be brought to your attention:
In paragraph 5, Runway Marking Precedence, the second sentence should be changed to read: "Where aiming points are relocated, the threshold will have to be displaced to retain the required distance from the threshold to the aiming point marking (see figure 3 for an example)."
In Table 1, Note 2 is also applicable to the aiming point markings for nonprecision instrument runways.
Paragraph 8d(2), Configuration B, references the runway threshold markings for configuration B. It says that the center space is 11.5 feet between the two innermost markings. However, the diagram in Figure 1 incorrectly shows the center spacing at 12 feet. The spacing should be 11.5, as indicated in the text.
In the last sentence of Paragraph 23a, the term "taxiway safety area" should be deleted and replaced by the term "taxiway object free area."
In paragraph 28a, the term "runway visible range (RVR)" in the last sentence should changed to "runway visual range (RVR)."
84. In Paragraph 3 of AC 150/5340-1G, Standards for Airport Markings, it states that glass beads may be used to increase the conspicuity of markings on taxiways or aprons but not on runways. Does this prohibit the use of glass beads on runways?
There is a concern that glass beads in runway markings may break away from the paint and increase the slipperiness of the runway surface. Because of this concern the FAA is conducting tests on the glass beads. Until the tests are completed, we do not recommend that glass beads be used on runways.
85. Paragraph 8 states that the Runway Threshold Marking starts 20 feet from the runway threshold and this dimension is shown in figures 1 and 2. However, figure 5 which illustrates a displaced threshold shows a dimension of 10 feet to 20 feet between the runway threshold markings and the runway threshold bar. Adding the 20 feet dimension to the width of the threshold bar (10 feet) means that the beginning of the threshold marking would be located 30 feet instead of 20 feet from the actual threshold. Would you please clarify which dimensions should be used?
When a threshold bar is not present, the threshold markings should begin 20 feet from the actual runway threshold. However, when a threshold bar is present, as in the case of a runway with a displaced threshold, it is preferable that the threshold markings begin 30 feet from the actual threshold. This allows a spacing of 20 feet between the threshold bar and the threshold markings. In developing these standards, it was recognized that some airport operators would have to shift their markings along the entire runway by 10 feet to accommodate a threshold bar. To preclude shifting the markings by 10 feet, the standards allow a spacing of 10 feet rather than 20 feet between the threshold bar and threshold markings. Paragraph 8b will be revised to note that the dimension of 20 feet may be increased to 30 feet when a threshold bar is present.
86. Paragraph 19b(2) and b(3) of AC 150/5340-1G, Standards for Airport Markings, are confusing as to when a taxiway centerline should be extended onto a runway and when it may be painted over the runway markings. Would you please provide clarification on these matters?
Paragraph 19b(2) addresses the centerlines for taxiways that are used as entrances or exits for the runway. The centerline becomes a lead-in or lead-off line and may cross over all runway markings with the exception of the designation marking. In the previous version of the AC 150/5340-1F, the standards specifically stated that for taxiways located at the runway end, the taxiway centerline ended at the runway edge, i.e., lead-in and lead-off lines were not installed for these taxiways unless there was a displaced threshold. These standards for lead-in and lead-off lines at the runway ends were inadvertently omitted from the 150/5340-1G version and will be incorporated when a change is issued.
Paragraph 19b(3) addresses taxiway centerlines where a taxiing route crosses the runway. In these cases the taxiway centerline may continue across the runway but is interrupted by any runway markings with one exception. The exception applies to taxiing routes that have been approved for Category III operations. In this case the taxiway centerline continues across all runway markings with the exception of the runway designation marking.
87. Can surface painted location signs be painted on runways?
Paragraph 24 and 25 in AC 150/5340-1G, Standards for Airport Markings, specifically say that holding position signs and the taxiway direction signs should not be painted on runways.
Surface painted location signs, like the painted holding position signs and the taxiway direction signs, should not be painted on runways. The AC will be changed to add a similar sentence to paragraph 26 as found in paragraphs 24 and 25.
88. Paragraph 35a of AC 150/5340-1G, Standards for Airport Markings, does not provide specific information on where the crosses at each runway end should be placed to indicate a temporary closure. The previous edition, AC 150/5340-1F, specifically stated that the crosses should be placed on top of the runway designation markings. Is this still the case?
The crosses should still be placed on top of the runway designation markings. Paragraph 35a will be modified accordingly.
89. Paragraph 35b of AC 150/5340-1G, Standards for Airport Markings, says that when a lighted cross is used to provide a visual means of identifying a closed runway, that the cross be placed within 250 feet of the end of the runway. Does this refer to on pavement only?
While in most cases the raised lighted cross will be located on the runway, there may be times when it is necessary to place the cross off the pavement in the safety area on the extended runway centerline. This is permissible provided that it is located no farther than 250 feet from the end of the runway.
90. Can replacement sign panels for lighted signs be ordered from a manufacturer who is not the original manufacturer of the sign fixture?
For signs qualified under AC 150/5345-44D, Specification for Runway and Taxiway Signs, it is recommended that the original manufacturer provide the sign panels. Installation of panels by another manufacturer may have an effect on the environmental characteristics of the sign. Panels of a different manufacturer may be installed only if the manufacturer provides a certification that the sign will continue to meet the specifications in AC 150/5345-44D. New lighted signs qualified under AC 150/4345-44E and -44F must meet luminance requirements. Replacement panels for these signs should only be provided by the original manufacturer in order to ensure continued compliance with the environmental and photometric requirements. (AC 150/5345-44F was signed last week by AAS-1 and includes specifications for retroreflective signs. This AC should be available within the next several weeks.)
91. Are airports at which ATC conducts land and hold short operations currently, required to have appropriate signs and markings at this time?
There has been much confusion regarding the requirements for installation of holding position markings and signs on runways to support land and hold short operations. At the time AC 150/5340-18C, Standards for Airport Signs, was issued in July 1991, we anticipated that Air Traffic would shortly be publishing standards for land hold short operations. To anticipate this, we put out guidance requiring holding position markings to be installed no later than Oct. 1, 1992.
Because of internal issues that arose, the Air Traffic Order has not yet been approved. This order is now being coordinated before final approval. Copies have been sent to each regional Airports division for comments. As written, it will require agreement between the airport operator and the ATC manager on the number and location of hold short points and will establish deadline dates after which hold short operations must be terminated if the appropriate signs, markings and lights are not in place. Until this order is approved and the individual agreements consummated, there is no longer any reason to violate airport operators for not having markings and signs in place. We should, however, continue to encourage the airport operators to coordinate with the local AT manager and to take the necessary steps to install the required signs and markings as soon as possible.
SIGNS and MARKING SUPPLEMENT #12
April 1, 199492. There have several instances when a taxiway or a portion of a taxiway has been used as a runway during daylight hours and in visual meteorological conditions (VMC). What are the proper markings and signing in this type of situation?
There are several things which must be considered here to achieve the proper markings and signing. Basically, a piece of pavement can not be marked as both a taxiway and a runway at the same time - that is, it can not have a yellow centerline and white designation numbers. (NOTE: On airports subject to National Environmental Policy Act requirements, a proposal to use a taxiway as a runway should include a review of the environmental consequences of such an action.)
1. If the pavement is to be used as a runway during the day, it should be painted, as a minimum, with visual runway markings, i.e., white designation numbers and a white centerline. Further, if it used as a runway at night and is to be lighted, it is to have white edge lights.
2. If the pavement is to be used ONLY as a taxiway at night, blue lights are acceptable in lieu of the white edge lights.
3. In either case, the Airport Layout Plan, as well as other appropriate documents, must be updated to indicate the presence of the runway. If the runway is to be used ONLY as a taxiway at night and blue edge lights have been installed, then the runway is to be listed as unlighted along with an appropriate annotation in the Airport/Facility Directory (A/FD) and the Airport Master Record (5010) indicating that the runway is closed to nighttime operations and that blue lights are provided for taxiing aircraft.
4. Since the pavement is now considered a runway, any taxiway intersecting the designated runway must have appropriate holding position lines and signs placed in accordance with AC 150/5340-1G and AC 150/5340-18C.
93. What actions are necessary to close a runway permanently and convert the pavement to a taxiway?
1. If the pavement is to be used as a taxiway, then all runway markings including the runway designation numbers are to be obliterated. The centerline is to be painted yellow. Any edge lights should be blue. Aircraft should not be permitted to land on or takeoff from a taxiway.
2. Xs are used to indicate that a runway or taxiway is closed to aircraft. Consequently, it is improper to place Xs on a runway if it is intended that the runway will be used as a taxiway.
3. The holding position lines must be removed and appropriate signs installed to indicate the existence of a taxiway.
SIGNS and MARKING SUPPLEMENT #13
September 20, 199494. In SAMS #11, question 84, you indicated that the FAA was conducting tests to determine if glass beads could be used on runways. What is the status of these tests?
The tests have been completed and the results indicated that the use of beads on runways does not significantly reduce the runway friction coefficient. Based upon these research results, the last sentence of Paragraph 3, Marking Practices of AC 150/5340-1G, Standards for Airport Markings will be revised to read as follows:
- Glass beads, meeting the requirements of Federal specification TT-B-1325, Type I or Type III Beads (Glass Spheres) Retroreflective, may be used to increase the conspicuity of markings.
- Until the AC is officially changed this SAMS should be considered as authorization to use beads in the paint on runways.
- The tests referred to above also showed that the friction coefficient of a painted surface could be significantly improved by adding sand to the paint. These results were same for paint with beads, as well as paint without beads.
SIGNS and MARKING SUPPLEMENT #14
May 19, 199895. The threshold markings characteristics described under Paragraph 8.d(2) Configuration B of AC 150/5340-1G, Standards for Airport Markings, will be the only threshold markings acceptable to the FAA after January 1, 2008. What should airport owners, airport planners and consulting engineers be doing now?
Federal Aviation Administration Advisory Circular (AC) 150/5340-1G, Standards for Airport Markings, contains standards for markings used on airport runways, taxiways, and aprons. Paragraph 8 of this AC, Runway Threshold Marking, provides standards for two different configurations of threshold markings. Configuration A represents a layout that has been traditionally used in the U. S. while Configuration B represents a layout that conforms with the International Civil Aviation Organization standards contained in Annex 14. Either configuration is currently acceptable. However, only Configuration B will be acceptable after January 1, 2008.
We realize that 2008 seems a long way off. However, the basis for allowing such a long compliance period was the premise that during this period most runways would be overlayed or reconstructed. Installation of the new threshold marking configuration in conjunction with a runway paving project would minimize the number of situations where markings would have to be removed or obliterated in order to install the new threshold configuration by 2008.
Unfortunately, Configuration A markings have recently been installed as part of a number of runway projects. This means that in ten years the airport operator is going to incur costs to obliterate these markings and replace them with Configuration B. Airport operators should be transitioning now to the Configuration B threshold markings whenever they are involved with a runway paving or reconstruction project.
96. The runway threshold markings required under Configuration B of AC 150/5340-1G, Standards for Airport Markings, for a 75 feet (23 m) wide precision instrument runway will be touching the runway side stripe marking. What should be the width of the runway side stripe marking to prevent this situation?
In order to comply with ICAO standards all runway threshold markings will be in accordance with Configuration B by January 1, 2008. To preclude the runway threshold markings from touching the runway side stripe, the width of the runway side stripe will be changed by the above date to be consistent with ICAO standards or as soon as an airport implements Configuration B. Paragraph 11.d. of AC 150/5340-1G, Standards for Airport Markings, is being changed as follows:
"11.d. Characteristics. The stripes have a minimum width of 36 inches (90 cm) for runways 100 feet (30 m) or wider and at least 18 inches (45 cm) for other runways. The stripes extend to the end of displaced threshold areas which are used for takeoffs or rollouts."
SIGNS and MARKING SUPPLEMENT #15
October 14, 199997. AC 150/5340-1H, Standards for Airport Markings, paragraph 23.d. states that "On angled taxiways the distances given in Table 4 defines the edge of the holding position line closest to the runway centerline." This revision to the standards previously contained in AC 150/5340-1G was prompted by a comment received during the FAA/Industry coordination of Draft AC 150/5340-1H.
A number of comments have been received indicating that implementing this chang e could have significant impact on certificated airports, because it will result in a requirement to relocate many hold lines and the associated holding position signs. In addition, a number of airports which have surface movement guidance and control system (SMGCS) routes may have to relocate in pavement stop bars and/or runway guard lights.
After review and discussion with several regions, a consensus has determined that these angled taxiways are for the most part used by aircraft exiting the runway, and rarely used by aircraft to taxi for departure. Operators of ground vehicles performing routine maintenance activities such as snow removal or airport inspections are more likely to use them than aircraft.
After taking into account the economic impact th at relocating these angled taxiways could have on airports and the minimal additional safety enhancement, the location of angled taxiways will continue to be determined by a perpendicular distance in accordance with Table 4 of the Advisory Circular and measured from the runway centerline to the intersecting taxiway centerline. AC 150/5340-1H will be changed sometime in the future to reflect the guidance provided in this sign and marking supplement.
SIGNS and MARKING SUPPLEMENT #16
May 29, 200198. Land and Hold Short Signs for designated points and taxiways. Based on FAA Order 7110.118 LAHSO, AAS is responsible for developing design and installation standards for signs required for Land and Hold Short Operations (LAHSO). Currently, Advisory Circular 150/5340-18C and SAMS #10 describe standards for land and hold short of Runway/Runway operations. The following is the design and installation standards for land and hold short of approach/departure flight path, designated point and intersecting taxiway operations.
LAHSO of a designated point occurs when an aircraft lands and holds short of a point predetermined on the landing runway. As an example: an aircraft lands on Runway 18 and holds short of designated point one. The sign should appear as 
. The design of the sign should be in accordance with the Mandatory Instruction Sign standards, Type L-858R, found in AC 150/5345-44F, Specification for Taxiway and Runway Signs. It shall be located on both sides of the runway at a point predetermined by air traffic control and the airport operator. These signs should be numbered in consecutive order such as HS-1, HS-2, and HS-3, as the procedures are developed. The land and hold short of a designated point sign, shall be used for a land and hold short of an approach/departure path operation.
LAHSO of a runway/taxiway intersection occurs when an aircraft lands and holds short of an intersecting taxiway. As an example: an aircraft lands on Runway 36 and holds short of Taxiway A. The sign should appear as 
. The sign should be designed in accordance with the Mandatory Instruction Sign standards, Type L-858R, found in AC 150/5345-44F, Specification for Taxiway and Runway Signs. The sign shall be 88.50 inches wide for size one, 108.18 inches wide for size two signs and 127.68 inches wide for size three signs. The letters must be centered on the sign and there shall be no seams dividing the characters. There must be enough "red" showing to make the sign conspicuous. The sign shall be located on both sides of the runway. The signs should be located at a distance from the intersecting taxiway to meet the clearance requirements of the intersecting taxiway as specified in AC 150/5340-18C, Table 1.
SIGNS and MARKING SUPPLEMENT #17
September 5, 200199. On some airports there are runways used solely by the military and do not carry a runway designation. What type of Mandatory Hold Signs and Markings should be used to designate these Military Assault Strip/Landing Zones?
A standard runway holding position marking should be placed on any taxiway leading onto or across a military assault strip. The setback distance should be based on the Table 4 of AC 150/5340-1.
The inscription on the Mandatory Hold Sign located at the intersection of a taxiway or designated runway and a military landing zone/assault strip that does not have a runway designation is: 
The design of the sign should be in accordance with the Mandatory Instruction Sign standards, Type L-858R, found in AC 150/5345-44F, Specification for Taxiway and Runway Signs. AC 150/5340-18C, Standards for Airport Sign Systems, Table 1, establish the standards for the location of this sign, i.e., the mandatory hold sign should be co-located with a taxiway location sign and Runway Holding Position Markings. This sign has been coordinated with the Department of Defense Federal Aviation Administration Liaison Detachment and Air Traffic Control Flight Procedures.
SIGNS and MARKING SUPPLEMENT #18
August 22, 2002100. For the purposes of marking a runway with precision markings, where is the midpoint of the runway when there is a displaced threshold on at least one end?
The midpoint of the runway is measured between the displaced threshold and the opposite runway end or between the 2 displaced thresholds if both are displaced.
101. If there is a precision approach on only one end of a runway with the other end nonprecision or visual, how would the runway be marked?
There are 2 ways it can be marked:
- Both sides can be marked as a precision approach to keep the symmetry of the runway markings; or
- The precision approach end would be marked with precision approach markings and nonprecision or visual markings at the other end. This could mean that the touchdown zone markings may extend past the midpoint of the runway. The end result would be a nonsymmetrical marking of the runway. AC 150/5340-1H says that there is no elimination of the touchdown zone markings when they are installed on only one end of the runway.
102. How are the touchdown zone markings placed on a runway with precision approaches on both ends?
The touchdown zone markings are placed symmetrically on both sides of the midpoint keeping the mid 1800 feet (900 feet either side of the midpoint) free of the touchdown zone markings. Those pairs of markings, which extend within 900 feet of the runway midpoint are eliminated
As an example, runway 4/22 is 8020 feet long. It has a displaced threshold on runway 4 of 1300 feet. There are precision approaches on both ends and runway 22 is the preferred landing runway. As the runway, measured from the displaced threshold on 4 to the opposite end, is 6720 feet, the midpoint is 3360 feet. Keeping the 900 feet either side of the midpoint free of markings, this would leave approximately 2460 feet. A full set of touchdown zone markings extends 3075 feet from the bottom of the threshold markings. This means that some of the markings will have to be eliminated. Rather than have to do the math to figure out which markings have to be eliminated, table 3 in AC 150/5340-1H does this for you. In this example, the 2 pair of single markings would be eliminated.
While in the example above, runway 22 is the preferred runway for landing, it is not appropriate to put a full set of touchdown zone markings on runway 22. A full set of touchdown zone markings is 3075 feet long. The runway from the runway 4 displaced threshold to runway 22 is 6720 feet. Subtracting the 3075 feet from the 6720 feet results in a distance of 3645 feet of which 1800 feet must remain clear of markings. This means that there is only 1845 feet on the runway 4 side for the runway 4 precision markings. This would translate into the elimination of the 2 sets of single bars and 1 set of double bars on runway 4. However, the midpoint of the runway is not free of markings.
103. Where is the beginning of the useful runway when the area around the landing threshold lights has been paved?
Recent installations of landing threshold lights has caused confusion over whether pavement used for such installations is considered the beginning of the useful runway. FAA’s Airway Facilities (AF) Offices and airport operators have been paving areas behind the landing threshold lights to prevent soil erosion and the creation of foreign object debris. This use of pavement has presented the question of whether the FAA should require airport operators to install a runway threshold bar marking to delineate the beginning of the useful runway, as specified in AC 150/5340-1H, Standards for Airport Marking. AC 150/5340-1H(13)(a) states a "threshold bar delineates the beginning of the runway that is available for landing when there is pavement aligned with the runway on the approach side of the threshold."
At airports certificated under 14 CFR part 139, or involved in a federally-funded runway construction project, the following marking procedures are to be used:
- If the installation of landing threshold lights requires pavement support and this pavement abuts the threshold of the runway, then that pavement should be considered a part of the lighting installation. In such instances, the installation of a runway threshold bar is not required.
- When there is pavement installed in excess of five feet from the landing threshold of the runway:
- And it appears that the pavement may be part of the actual runway; or
- does not have the same weight bearing capacity as the runway,
SIGNS and MARKING SUPPLEMENT #19
March 10, 2004104. Should runway exit signs be illuminated with the associated runway lights or the associated taxiway lights?
Confusion over FAA guidance regarding the illumination of runway exit signs has resulted in airport operators lighting these signs in an inconsistent manner. While the FAA intended runway exit signs to be illuminated with the associated runway lights, some airport operators are illuminating runway exit signs with the runway lights and others are lighting these signs with the associated taxiway lights. This inconsistency may stem from conflicting guidance contained in AC 150/5340-18C and terminology used in Signs and Marking Supplement #8.
Paragraph 4d on the signature page of AC 150/5340-18C states that generally, “ . . . signs should be lighted if the runway or taxiway on which they are installed is lighted.” However, Paragraph 14 of this AC addresses which signs should be illuminated with other signs and provides guidance somewhat contrary to Paragraph 4d. Paragraph 14 states the airport operator should illuminate holding position signs for runways, ILS critical areas, approach areas, and their associated taxiway location signs when the associated runway lights are illuminated. Other taxiway guidance signs are to be illuminated when the associated taxiway lights are illuminated.
Paragraph 14 caused confusion regarding the illumination of a runway exit sign if the taxiway associated with the sign does not have lights. In response, a clarification was issued in Signs and Marking Supplement #8 (issued May 29, 1992), Question #70, that stated "runway exit signs should be lighted if the runway on which they are located is lighted and the associated exit taxiway is lighted or has either edge or centerline reflectors."
The FAA intended in its response to Question #70 to require runway exit signs to be lit with the runway lights on which they are located, not the associated taxiway. However, several airport operators and consultants working on airport sign/lighting projects have interpreted the word “should” in the last paragraph of Question #70 to mean they have the discretion to connect runway exit signs to either the associated runway or taxiway lighting system circuit.
Runway exit signs indicate to the pilot where to exit the runway and thereby need to be visible to a pilot while on the runway. Accordingly, runway exit signs must be lit with the associated runway lights so there is no confusion as to where a pilot should exit the runway. This is particularly important at airports where taxiways are unlit or the taxiway lighting system is out-of-service and unusable pavement or other areas adjacent the runway, such as a service road, may appear to be a taxiway during low visibility conditions. Illuminating runway exit signs with the associated runway lights also eliminates the potential of these signs being inadvertently turned off during certain types of low visibility operations, such as Surface Movement Guidance and Control System operations, or during times when the airport is uncontrolled and pilots are only able to activate runway lights.
To address these issues and ensure all runway exit signs are illuminated in the same manner, new or renovated runway exit signs must be illuminated when the associated runway lights are illuminated. This change is effective immediately and will be incorporated in the next revision of Advisory Circular (AC) 150/5340-18C, Standards for Airport Sign Systems. This revised lighting standard is an acceptable means of compliance with lighting requirements of 14 CFR part 139 and AIP-funded projects.
Similar to the standard for illuminating holding position signs, there is no requirement that runway exit signs be on the same lighting circuit as the runway lights (see SAMS #74). While connecting runway exit signs to the same electrical circuit as the runway lights may be the most feasible means to illuminate these signs with the runway lights, this can be accomplished through a procedural methods, i.e., a lighting control panel operated by air traffic control personnel. Such procedural methods of lighting runway exit signs must ensure that these signs are always illuminated whenever the runway lights are illuminated.
SIGNS and MARKING SUPPLEMENT #20
June 10, 2005105. With the introduction of the enhanced taxiway centerline (see AC 150/5340-1J, paragraph 21 e.), how far back does the enhanced centerline continue?
The Advisory Circular (AC) 150/5340-1J, Standards for Airport Markings, includes several scenarios regarding the length of the enhancement. Basically, the enhanced taxiway centerline extends back a maximum of 150 feet. Appendix 3 of the AC gives an example where the line may extend less than 150 feet as depicted in Figure C-10.
Another situation where the enhancement may not extend the full 150 feet involves the location of the ILS holding position marking. Where there is an ILS holding position marking less than 150 feet from a regular holding position marking, the enhancement should stay within the confines of the two holding position markings and not proceed beyond the ILS holding position marking.
106. Note 2 in appendix 3 of AC 150/5340-1J indicates that a taxiway centerline might have to be shifted either right or left to the enhancement does not go over the taxiway centerline light. Is it then a requirement to move the taxiway centerline or the taxiway centerline lights to avoid this problem?
It is NOT a requirement to move the taxiway centerline or the taxiway centerline lights to accommodate the enhanced markings. We realize that this new marking requires a wider width due to the black outlining and the additional dashed lines. It is permissible to leave the taxiway centerline and the taxiway centerline lights where they are currently located and, if necessary to cover or screen the centerline fixture during the installation of the enhanced markings.
If the pavement is to be overlaid or reconstructed and adequate space is available, it is preferable to shift the centerline to eliminate the overlap between the enhanced centerline and the centerline lights.
107. AC 150/5340-1J, paragraph 23 b., addresses the extension of the holding position markings onto paved shoulders of a taxiway. If an airport operator extends the holding position marking on taxiway serving an air carrier runway, does the airport operator have to put in the extension on every taxiway?
No, the extension of the holding position markings onto paved taxiway shoulders is for easier visibility for the crew of Aircraft Design Groups 5 and 6. If these design groups will not be operating on certain taxiways, the holding position markings would not have to be extended on those taxiways in such cases.
SIGNS and MARKING SUPPLEMENT #21
September 9, 2005108. The enhanced centerline in AC 150/5340-1J, Standards for Airport Markings, in Figure C-1 indicates a 3 inch black border on the outside of the enhancement. Paragraph 4 a (1) of the AC indicates that black borders be 6 inches or greater. Can the black border on the enhanced centerline be increased to 6 inches so that spray nozzles on painting equipment would not have to be adjusted?
The black outlining of the outside of the enhanced centerline marking may be from 3-6 inches (7.5 cm to 15 cm).
109. In SAMS 20, question 106, it was recommended that the taxiway centerline lights be covered if their location interfered with the enhanced taxiway centerline markings. If they are covered during the spraying, does the airport operator have to go back and paint the housings to ensure the integrity of the enhancement?
There was no intention that the centerline light housing had to be painted. They may be left unpainted even if they are in the area of the painted markings.
110. When the runway holding position marking is extended beyond the taxiway edge marking, what is the correct distance of the taxiway edge marking from the runway holding position marking? Figure C-3 of AC 150/5340-1J, Standards for Airport Markings, has a parenthetical phrase that contradicts the sentence immediately before it. Additionally, paragraph 23 (b) (2) (ii) and (iii) indicate that the taxiway edge markings abut the holding position marking if the holding position marking is not outlined in black or the black outline if the holding position marking is outlined in black.
The taxiway edge markings should abut the runway holding position marking according to paragraph 23 (b) (2) (ii) and (iii) in AC 150/5340-1J.
111. If an airport is required to install the enhanced holding position markings, should they be installed all at once or can they be installed over a period of time before the June 30, 2008, deadline?
The installation of these markings should be concurrent.
SIGNS and MARKING SUPPLEMENT #22
November 7, 2005112. If an airport operator installs a surface painted holding position sign on the left of the taxiway centerline, does one need to be installed on the right side of the centerline?
AC 150/5340-1J, Standards for Airport Markings, par 26b, states that surface painted holding position signs are located both to the left and to the right of the taxiway centerline. However, the second surface painted holding position sign on the right side was not intended to be mandatory. It is preferred that, when one surface painted runway holding position sign is used, it be placed on the left side of the centerline. If a second runway surface painted holding position sign is used, it is located on the right side of the centerline. The sign is never painted across the centerline. The use of the second surface painted runway holding position sign is highly recommended (but not required), especially when (a) aircraft that require a two person crew operate on a regular basis or (b) the holding position marking is located on the parallel taxiway rather than on the stub taxiway.
113. In paragraph 26 a. of AC 150/5340-1J, there is a requirement that there be a surface painted holding position sign on taxiways (or run-up pads) that are over 200 feet wide. Normally a taxiway centerline would be near the edge of the pavement and a surface painted holding position sign would be placed on the left hand side of that centerline. The AC further states that if the taxiway centerline is closer than 35 feet from the edge of the taxiway and the mandatory holding position sign is in clear view, then the surface painted holding position sign may be eliminated. Why was 35 feet used since the centerline would, in most cases, be 37 ½ feet from the edge of the taxiway?
The purpose of the 35 feet was to allow an airport operator the option to eliminate that surface painted holding position sign since it would serve little purpose, being so close to the vertical mandatory holding position sign. Normally, most taxiway centerlines would be at least 37 ½ feet from the edge of the taxiway. The 35 feet was used erroneously. We will change that sentence in the AC to read "If a taxiway centerline is closer than 45 feet from the edge of a taxiway and the mandatory hold sign is in clear view, the surface painted holding position sign on that side of the taxiway centerline may be eliminated."
114. If the width of a taxiway exceeds two hundred feet and the centerline for the taxiway is not located an equal distance from the edges of the taxiway, where should the surface painted holding position signs be located?
AC 150/5340-1J, Standards for Airport Markings, paragraph 26 a. requires surface painted holding position signs when the taxiway is greater than 200 feet. A surface painted holding position sign should be painted on the left side of any taxiway centerline on that pavement. The AC also states that if the vertical mandatory holding position sign is in clear view and the taxiway centerline is closer than 35 feet from the edge of the taxiway (to be changed to 45 feet, see Q & A 113, above), the surface painted sign may be omitted. We highly recommend that on an expanse of pavement greater than 200 feet that at least one surface painted holding position sign be in the middle of such expanse or every 100 feet. (See sketch on last page of this SAMS.) The intent of this requirement is to give to a pilot a visual cue that can be seen wherever that aircraft may be located on the expanse of pavement. However, the same prohibition applies, in that the surface painted sign cannot be located over the centerline.
115. A taxiway goes into the intersection of two runways. This configuration prompts a holding position sign that depicts number designations for both runways. The standard also requires arrows that depict the approximate orientation of the two intersecting runways. An airport operator wants to install surface painted holding position signs as a runway safety initiative on this 75 foot-wide taxiway. However, there's just not enough space for both runway designations and the associated arrows. Is it acceptable to delete the arrows on the surface painted sign?
In the situation described in this question, the arrows may be eliminated. Air traffic communications only refer to the active runway; for this reason it is more important to have the designations of both runways in the surface signs. While we realize that the surface painted holding position sign does not mirror the vertical signs in this case, we feel that this safety enhancement is of benefit to the aircraft pilot.
116. In situations where there is no Land And Hold Short Operation and generally no taxiing operations on a runway, a minimum of one holding position sign is required at every runway/runway intersection. If an airport wants to exceed that minimum standard by installing and maintaining an additional sign on the right and/or a holding position marking on the pavement, is this acceptable relative to standards in AC 150/5340-1J and AC 150/5340-18D?
Many airports are being quite proactive and want to go "above and beyond" what they perceive as the minimum requirements defined in our standards. Airports now often want to provide visual cues to identify the intersecting runway environment, especially for their own maintenance and snow removal equipment operators. To promote situational awareness, we feel that the addition of a 2 nd holding position sign where only one is required may provide a benefit in the reduction of runway incursions. Two holding position signs with no holding position marking on the runway is acceptable, unless otherwise required by the standard to support taxiing or LAHSO. Except where required by the standard as noted above, one runway/runway holding position sign on the left with a holding position marking on the runway is also acceptable. Before adding the holding position marking on the runway, the airport operator should ensure coordination with the Airport Traffic Control Tower as applicable.
SIGNS and MARKING SUPPLEMENT #23
January 10, 2006117. How should the enhanced taxiway centerline dashes be applied to a taxiway centerline that intersects the holding position marking at other than a 90 degree angle?
When a taxiway centerline intersects the holding position marking at an angle other than 90 degrees, the enhancement dashes on either side of the centerline would start and stop at different locations if both dashes were nine feet in length. In this situation it is more important that the dashes end at the same location relative to the centerline than the fact that each dash is exactly nine feet in length. The following procedure should be followed for laying out the dashes in this situation:
Each dash in the first set of dashes will always start the same distance from the first solid bar of the holding position marking as the taxiway centerline (i.e. 6 to 12 inches). To locate the end point of the first set of dashes, measure 9 feet along the taxiway centerline. An imaginary line perpendicular to the taxiway centerline at this point will mark the end of the first dash enhancement on each side of the centerline. (Note: One dash will be longer than nine feet while the other will be shorter than nine feet.) See Figure 117.
If the centerline is straight, measure three feet from the imaginary line above (or from the end of the first set of dashes) to identify the beginning of the next set of dashes. The second set of dashes and all subsequent dashes will be nine feet in length with spacing of three feet between each set of dashes. If the centerline is curved, see SAMS 118 for the proper application.
Figure 117.
Note: All measurements are taken along the center of the centerline.
118. How should the enhanced dashes be applied to a centerline that is curved rather than straight?
When a taxiway centerline is curved, the enhancement dashes on either side of the centerline would start and stop at different locations if both dashes were nine feet in length. In this situation it is more important that the dashes end at the same location relative to the centerline than the fact that each dash is exactly nine feet in length. The following procedure should be followed for laying out the dashes in this situation:
Each dash in the first set of dashes will always start the same distance from the first solid bar of the holding position marking as the taxiway centerline (i.e. 6 to 12 inches). To locate the end point of the first set of dashes, measure along the taxiway centerline. An imaginary line perpendicular to the tangent of the taxiway centerline at this point will mark the end of the first dash enhancement on each side of the centerline. Measure an additional three feet along the curved centerline and an imaginary line perpendicular to the tangent of the curve will mark the starting point for the second set of dashes. The ending point for this set is found by measuring nine feet along the center of the curved taxiway. An imaginary line perpendicular to the tangent at this point will mark the end of the second set of dashes. (See Figure 118.) Repeat the procedure for the remaining curved portion of the centerline. Except for the first set of dashes the dashes on the outside of the curve will be longer than nine feet while the dashes on the inside of the curve will be shorter than nine feet.
Figure 118.
Note: All measurements are taken along the center of the centerline.
119. Paragraph 21 e (3)(ii) of AC 150/5340-1J discusses the situation where an enhanced centerline continues from one holding position marking to a second holding position marking. How should the enhanced centerline be applied in this case?
You should start the enhanced centerline from both holding position markings. It is okay if the dashes at the mid point of the centerline (or adjacent to it) are less than or more than the length specified in the standard. A difference of a few feet in the length of the dash would not really be noticeable to most pilots. The goal here should be to maintain the pattern of a long dash and a much shorter space on each side of the centerline.
120. Paragraph 21 e (3)(iii) of AC 150/5340-1J discusses the situation where two taxiway centerlines come together (converge). This paragraph states that there should be no partial dashes (less than nine feet in length) at the convergence. We believe that not painting dashes that are less than nine feet breaks up the enhancement pattern. Is it permissible to paint partial dashes?
The prohibition on partial dashes was put in place as an attempt to save time in paint layout and application. However, there are cases where dashes should be painted that are less than nine feet in length, e.g., the dashes on the inside of a curved taxiway centerline. For this reason, the prohibition against painting partial dashes is being revoked. The revised Paragraph 21 e (3)(iii) of AC 150/5340-1J will read as follows:
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(iii) Where two taxiway centerlines come together (converge) at or before the runway holding position marking, both dashes located at the convergence on the outside of the two centerlines will be full dashes. Dashes at the convergence located between the two centerlines must end at the same point relative to the respective centerline as the outside dash. It is permissible to omit any dash that will be less than five feet in length. (See Figure 120a and 120b.)
Figure 120a.
Partial dashes included because they exceed five feet in length.
Figure 120b.
Partial dashes omitted because they would be less than five feet in length.
121. If two taxiway centerlines converge at or near a holding position marking (at different angles to the holding position marking), the dashes will end at different locations relative to each centerline. How do you layout the enhancement dashes in this case?
When two centerlines converge at or near a holding position marking, the enhancements for each centerline should be laid out separately in accordance with the procedures contained in SAMS 117 and 118. (See Figure 121.) The two dashes between the taxiway centerlines are included in this figure because they exceed five feet in length. If they were less than 5 feet in length, they may be omitted. It is permissible to overlap the interior dashes for each centerline (as shown in the figure) provided that each dash remains at least six inches from both centerlines. The key element of this installation is that first set of dashes for each centerline end at the same point relative to that centerline.
Figure 121.
