Precision runway monitor

In aviation, precision runway monitor (PRM) is a high-speed, high-precision radar system developed by Raytheon to monitor simultaneous close parallel instrument approaches to airports. PRM contains no moving parts and scans at a rate of once per second, allowing monitoring of approach corridors with accuracy of about one milliradian.

PRM is one type of radar system that can be used to allow simultaneous approaches on parallel runways that are spaced less than 1,310 metres (4,300 ft) to each other. Airports at which PRM is in use in the United States include Minneapolis, Philadelphia, San Francisco, Detroit, and Atlanta. International installations include Sydney, Australia, and Chek Lap Kok in Hong Kong.