“Altitude busts” heighten the risk of a midair collision, FAA enforcement action, and, in a descent, controlled flight into terrain. Flying through an assigned altitude is one of the most common occurrences in NASA Aviation Safety Reporting System (ASRS) write-ups. Even experienced airline pilots, with extra crewmembers in the cockpit to help avoid mistakes, sometimes fly through an assigned altitude. It’s *very* easy to do:
Climbing through IMC in congested airspace, you configure and trim your airplane for climb. As you’re nearing altitude a back seat passenger, nervous about flying in the light turbulence and clouds, leans forward to tell you he’s feeling ill. Distracted by the airsick passenger, you forget the clearance restriction and climb through your assigned altitude. Suddenly ATC calls for an immediate turn, and you come within 1000 feet of a commercial jetliner.
You dial the assigned altitude into your altitude-capturing autopilot, and are reviewing an instrument approach plate while your airplane descends through the assigned altitude. You look up and realize that you’d put wrong target altitude in your altitude preselect.
It’s dark, and few lights illuminate the hills below you. You’ve settled into descent, but you forgot to reset your altimeter. Suddenly a dark blur flashes past your window, then another suddenly you hear the awful first scraping sound as you clip the trees….
Altitude busts happen when pilots:
- Become distracted during a climb or descent;
- Misunderstand Air Traffic Control clearances or directions;
- Incorrectly input altitude information into altimeters or automated altitude capturing equipment; or
- Become dependent on autopilots and automatic level-off features, which may fail.
Remember: You’ve chosen or been assigned an altitude for a reason, whether for traffic avoidance or to maintain a minimum height above obstacles. If you deviate more than 300 feet from an assigned altitude and controllers have to redirect other airplanes because of your deviation, the ATC “snitch program” may automatically report you for a violation.
Avoid Altitude Busts By:
- Pay careful attention during climbs and descents. Establish a “no unnecessary conversation/unnecessary action” rule (a “sterile cockpit”) within 1000 feet of a level-off;
- Clearly read back all ATC altitude information as a means of verification, and of reinforcing the correct altitude target in your mind;
- Write or otherwise recording altitude assignments to avoid confusion later;
- Use care setting altimeters and programming automated level-off devices, and double-check your input; and
- Closely monitor altitude capture equipment when leveling from climbs or descents
Editor’s note: An altitude bust is the airborne equivalent of a runway incursion and the FAA’s opinion of altitude deviations can be witnessed in the courts — as well as a previous Insider Series article … The FAA, The Law, and Your Certificate.