Definition
A high-update-rate radar system used by air traffic control to monitor simultaneous independent instrument approaches to closely spaced parallel runways. PRM provides controllers with rapid position updates and automated alerts so that aircraft straying toward the adjacent approach course can be turned away before a loss of separation occurs.
Plain English
PRM is a fast, precise radar that lets controllers safely run instrument approaches to two parallel runways at the same time, even when the runways are close together. It updates aircraft positions quickly and warns the controller if a plane drifts toward the other approach.
Context Anchor
Seen in approach procedure names, chart notes, airport arrival procedures, and ATC instructions at airports that use closely spaced parallel runway operations.
Derivation
From 'precision' (high accuracy), 'runway' (the landing surface), and 'monitor' (to watch closely). The name describes its job: precisely watching aircraft on final approach to parallel runways.
Why Pilots Care
Allows safe, independent ILS approaches to closely spaced parallel runways that would otherwise require greater separation or staggered timing.
Intuition Check
PRM is not a cockpit instrument and not a separate kind of runway. It is a controller monitoring system used to keep parallel approaches safely separated.
Example Sentence 1
Approaching a busy hub with closely spaced parallel runways, the crew briefed the PRM approach and confirmed they were ready to react immediately to any breakout instruction.
Example Sentence 2
Controllers use PRM to issue immediate breakoff instructions if an aircraft deviates toward the adjacent approach path.