NATIONAL TRANSPORTATION SAFETY BOARD

Public Meeting of October 16 , 2007

(Information subject to editing)

Brief of Aviation Accident
Unmanned Aircraft Crash
Near Nogales International Airport
Nogales, Arizona, April 25, 2006
NTSB/AAB-07/

This is a synopsis from the Safety Board’s report and does not include the Board’s rationale for the conclusions, probable cause, and safety recommendations.  Safety Board staff is currently making final revisions to the report from which the attached conclusions and safety recommendations have been extracted.  The final report and pertinent safety recommendation letters will be distributed to recommendation recipients as soon as possible.  The attached information is subject to further review and editing.

EXECUTIVE SUMMARY

On April 25, 2006, about 0350 mountain standard time, a Predator B, an unmanned aircraft (UA) manufactured by General Atomics Aeronautical Systems, Inc., (GA-ASI) and operated by the U.S. Customs and Border Protection (CBP), crashed approximately 10 nautical miles northwest of Nogales International Airport, Nogales, Arizona, within 100 yards of a house that was located in a sparsely populated residential area.  There were no injuries to persons on the ground.  The UA, which was unregistered and owned by the CBP and operated under contract with GA-ASI, sustained substantial damage.  The UA was being piloted via data link from a ground control station (GCS) located at the Libby Army Airfield (FHU), Sierra Vista, Arizona.  The public-use flight originated from FHU and was performing U.S. Border surveillance in night visual meteorological conditions.  An instrument flight rules flight plan had been filed and activated for the flight.

The Predator B collided with the terrain following a loss of engine power while patrolling the southern U.S. border. 

PROBABLE CAUSE

The National Transportation Safety Board determines that the probable cause of the April 25, 2006, UA crash was the pilot’s failure to use checklist procedures when switching operational control from Pilot Payload Operator (PPO)-1 to PPO-2, which resulted in the fuel valve inadvertently being shut off and the subsequent total loss of engine power, and lack of a flight instructor in the GCS, as required by the CBP’s approval to allow the pilot to fly the Predator B.  Factors associated with the accident were repeated and unresolved console lockups, inadequate maintenance procedures performed by the manufacturer, and the operator’s inadequate surveillance of the UAS program.

SAFETY RECOMMENDATION

As a result of its investigation, the National Transportation Safety Board makes the following safety recommendations:

To the U.S. Customs and Border Protection:

1. Require GA-ASI to modify the UAS to ensure that inadvertent engine shutdowns do not occur.  (A-07-XX)
2. Require GA-ASI to modify the UAS to provide adequate visual and aural indications of safety-critical faults, such as engine-out conditions and console lockups, and present them in order of priority, based on the urgency for pilot awareness and response.  (A-07-XX)
3. Review the CBP’s methods of developing the lost-link mission profiles to ensure that lost-link mission profile routes minimize the potential safety impact to persons on the ground, optimize the ability to recover the data link, and, in the absence of data-link recovery, provide the capability to proceed to a safe zone for crash landing.  (A-07-XX)
4. Following completion of the action requested in Safety Recommendation [3], require that pilots be trained concerning the expected performance and flightpath of the UA during a lost-link mission.  (A-07-XX)
5. Require that the UAS be modified to ensure that the transponder continues to provide beacon code and altitude information to air traffic control even if an engine shuts down in flight and that the pilot is provided a clear indication if transponder function is lost for any reason.  (A-07-XX)
6. Review all UAS functions and require necessary design changes to the UASs that the CBP operates to ensure that electrical power is available to UA control following loss of engine power.  (A-07-XX)
7. Develop a means of restarting the UA engine during the lost-link emergency mission profile that does not rely on line-of-sight control, for example, through an autonomous capability in the UAS’s control system or through use of control functions enabled via a backup satellite communication system available to the pilot on the ground.  (A-07-XX)
8. Participate in periodic operational reviews between the UAS operations team and local air traffic control facilities, with specific emphasis on face-to-face coordination between the working-level controller and UA pilot(s), to clearly define responsibilities and actions required for standard and nonstandard UA operations.  (A-07-XX)
9. Require that all conversations, including telephone conversations, between UA pilots and air traffic control, other UA pilots, and other assets that provide operations support to UA operations, be recorded and retained to support accident investigations.  (A-07-XX)
10. Identify and correct the causes of the console lockups.  (A-07-XX)
11. Implement a documented maintenance and inspection program that identifies, tracks, and resolves the root cause of systemic deficiencies and that includes steps for in-depth troubleshooting, repair, and verification of functionality before returning aircraft to service.  (A-07-XX)
12. Require that aviation engineering and maintenance experts oversee the definition of maintenance tasks, establishment of inspection criteria, and the implementation of such programs.  The CBP also should ensure oversight of contractor(s) implementing such programs.  (A-07-XX)
13. Develop minimum equipment lists and dispatch deviation guides for the CBP’s UAS operations.  (A-07-XX)
14. Assess the spare-parts requirements for CBP’s UAS operations to ensure the availability of parts critical to UA launch, as defined by the minimum equipment list requirements.  (A-07-XX)
15. Revise CBP’s pilot training program to ensure pilot proficiency in executing emergency procedures.  (A-07-XX)
16. Require that a backup pilot or another person who can provide an equivalent level of safety as a backup pilot be readily available during the operation of a UAS.  (A-07-XX)
17. Develop a safety plan, which ensures that hazards to the National Airspace System and persons on the ground introduced by the CBP UAS operation are identified and that necessary actions are taken to mitigate the corresponding safety risks to the public over the life of the program.  The plan should include, as a minimum, design requirements, emergency procedures, and maintenance program requirements to minimize the safety impact of UAS malfunctions in flight, continuous monitoring of the CBP’s UA operation, analysis of malfunctions and incidents, and lessons learned from other operators of similar UAS designs.  (A-07-XX)

To the Federal Aviation Administration:

18. Require that UA transponders provide beacon code and altitude information to air traffic control and to aircraft equipped with traffic collision avoidance systems at all times while airborne by ensuring that the transponder is powered via the emergency or battery bus.  (A-07-XX)
19. Require that all conversations including telephone conversations, between UA pilots and air traffic control, other UA pilots, and other assets that provide operational support to UAS operations be recorded and retained in accordance with Federal Aviation Orders 7210.3 and 8020.11.  (A-07-XX)
20. Require periodic operational reviews between the UAS operations teams and local air traffic control facilities, with specific emphasis on face-to-face coordination between working-level controllers and UA pilot(s), to clearly define responsibilities and actions required for standard and nonstandard UAS operations.  These operational reviews should include, but not be limited to, discussion on lost-link profiles and procedures, the potential for unique emergency situations and methods to mitigate them, platform-specific aircraft characteristics, and airspace management procedures.  (A-07-XX)
21. Require that established procedures for handling piloted aircraft emergencies be applied to UAS.  (A-07-XX)
22. Require that all UAS operators report to the Federal Aviation Administration, in writing within 30 days of occurrence, all incidents and malfunctions that affect safety; require that operators are analyzing these data in an effort to improve safety; and evaluate these data to determine whether programs and procedures, including those under air traffic control, remain effective in mitigating safety risks.  (A-07-XX)