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Contact: John Black, Spokane, WA Safety Program Manager Posted On: March 29, 2006 "Resume Own Navigation, What does it really mean? A Scenario Based on Actual Events . . .

Picture this scenario: You are on a VFR flight in Class C Airspace on a vector enroute to a practice training area.  The air traffic controller issues you an altitude restriction by stating, "Cessna 1234 maintain VFR at or above 6000 and expect own altitude in about 7 miles."  A short time (couple minutes) later the controller amends the altitude restriction to maintain at or above 5500.  A few moments afterwards you then receive the clearance, "Cessna 1234 resume own navigation on course."  The bases of the clouds are trending lower as your flight progresses towards the practice area so you begin a descent in order to maintain appropriate separation from the cloud base.  As you descend through 5000 feet the controller calls you back and states, "Cessna 1234 you were told to stay at or above 5500!"   Suddenly, a chill goes down your back.  You think, "Did I do something wrong?  I remember the controller telling me to resume my own navigation."

Let's analyze this situation.  What does "Resume Own Navigation," when navigating VFR, really mean?   In the Pilot/Controller Glossary of the AIM, "Resume Own Navigation" is defined: "Used by ATC to advise a pilot to resume his/her own navigational responsibility.  It is issued after completion of a radar vector or when radar contact is lost while the aircraft is being radar vectored."  Applying this definition to this situation, it is difficult to ascertain who, if anyone (pilot or controller), erred.  What is obvious, however, is that a breakdown in pilot/controller communications has occurred.  The controller most likely issued the altitude restriction due to conflicting traffic and expected the Cessna to abide by the clearance whereas the pilot most likely thought "Resume Own Navigation" meant that all navigational responsibility had been transferred to him/her.  Since airplanes navigate in three dimensions, altitude was thought to be at pilot's discretion. 

Who's right?  Four operations inspectors based at a local FSDO office were given this scenario and were queried as to their opinion regarding the meaning of "Resume Own Navigation."  Unanimously, all four inspectors felt that "Resume Own Navigation" allowed the pilot to determine their own appropriate VFR altitude.  Speaking to air traffic controllers, however, yielded an opposing view.  Their position is that an altitude restriction is valid until canceled verbally by them.  So, who's right?  My answer is, it makes no difference.  If a hazard is created by a misunderstanding between pilot and controller, safety is degraded and we must come to a meeting of the minds in order to either mitigate the risks associated with the aforementioned hazard or eliminate the hazard altogether. 

What can be done?  On the pilot side, we need to be cognizant of our "situational awareness."  Airspace is oftentimes crowded, controllers are busy, but we are all share responsibility to ensure safe flight operations.  After being issued the instruction, "Resume Own Navigation," when previously issued an altitude restriction on a VFR flight, it would be advisable to ask if the altitude restriction is not repeated by the controller, "Am I still restricted to 5500 feet?"  Controllers too could enhance effective communications by adding a few key words to the "Resume Own Navigation" clearance by stating in this particular case, "Resume own navigation on course at or above 5500."  The chance for miscommunication or confusion would be virtually eliminated by adherence to the aforementioned suggestions.

Modifying the definition of "Resume Own Navigation" might also eliminate the apparent confusion associated with this clearance.  As with all governmental functions, however, that may take a little longer.  So in the meantime, let's concentrate on "situational awareness" aided by a little help from our ATC counterparts.  Together, we can work to either eliminate hazards within our system or at the very least, mitigate the risk associated with hazards that cannot be eliminated.  In case you haven’t guessed, this scenario is based on an actual occurrence, which resulted in the need for evasive action by the pilots of a large aircraft.

John Black
Safety Program Manager
Spokane, WA
1-509-532-2358
john.black@faa.gov