Aviation Maintenance Terms beginning with P

Position Source

The on-board avionics equipment that provides the latitude, longitude, geometric altitude, velocity, position and velocity accuracy metrics, and position integrity metric. Additionally, the position source may provide the vertical rate parameters.

Pressure Altitude

Altitude reported by a barometric pressure altimeter without corrections for local pressure settings.

Primary Surveillance Radar (PSR)

A radar sensor that listens for the echoes of pulses that it transmits to illuminate aircraft targets. PSR sensors, in contrast to secondary surveillance radar (SSR) sensors, do not depend on the carriage of transponders on board the aircraft targets.