Definition
An instrument approach conducted to one of a pair (or more) of closely spaced parallel runways where simultaneous independent operations are permitted. A dedicated final monitor controller, using high-update-rate surveillance, watches each aircraft on final and is authorized to issue breakout instructions if another aircraft deviates toward the No Transgression Zone between the parallel courses. Pilots must be specifically qualified and briefed for PRM operations and must monitor a separate PRM monitor frequency in addition to the tower frequency.
Plain English
An approach to one of two parallel runways being used at the same time, where a separate controller watches each aircraft closely on a special radar and can quickly tell a pilot to turn away if another aircraft strays too close. Pilots need special training and listen to an extra radio frequency for these instructions.
Context Anchor
Seen on instrument approach charts, in approach clearances, and during operations at busy airports with closely spaced parallel runways.
Derivation
Monitoring' here refers to the dedicated final monitor controller whose only job is to watch the approach and issue breakout instructions if needed. 'Precision Runway Monitor' refers to the high-update-rate radar system that makes this close watching possible.
Why Pilots Care
Allows busy airports to land more airplanes per hour on parallel runways while preserving the required safety separation.
Intuition Check
Monitoring does not mean the pilot can relax because someone else is watching. Here it means air traffic control is watching closely, and the pilot must be especially ready to respond immediately.
Example Sentence 1
Cleared for the ILS PRM Runway 28R approach, the crew tuned the tower frequency on COM1 and the PRM monitor frequency on COM2 before intercepting the localizer.
Example Sentence 2
When the adjacent aircraft began to drift toward their path, the pilot received a breakout instruction and executed the missed approach as trained.