Yoke mounted GPS units and other portable electronic systems may interfere with the operations of the aircraft controls. The clamping devices that hold these electronic units to the yoke may become jammed by the heating and cold air push/pull knobs if the yoke is moved briskly forward and turned hard right or left such as in a strong crosswind landing with the ventilation control knobs pulled full out. Portable GPS receivers can only be used as a supplemental aid to VFR in conjunction with an approved primary means of navigation. All portable electronic systems and portable GPS units must be handled in accordance with the provisions of 14 CFR part 91, § 91.21. The operator of the aircraft must determine that each portable electronic device will not cause interference with the navigation and communications systems of the aircraft on which it is to be used. Yoke mounts usually sold with a portable GPS unit must be mounted as to not interfere with the operation of the aircraft controls. Permanent mounts and externally mounted antennas for use with a portable GPS unit must be installed in an FAA-approved manner. A critical aspect of any GPS installation is the installation of the antenna. Shadowing by the aircraft structure can adversely affect the operation of the GPS equipment. Operators should be aware that a GPS signal is weak, typically below the value of the background noise. Electrical noise or static in the vicinity of the antenna can adversely affect the performance of the system.
Also read: AC 20-173
For further information contact:
Bob Wesner,
FAASTeam Program Manager, (FPM)
(907) 457-9241,
robert.f.wesner@faa.gov
