Precision Runway Monitor (PRM) System

Provides air traffic controllers monitoring the NTZ during simultaneous close parallel PRM approaches with precision, high update rate secondary surveillance data. The high update rate surveillance sensor component of the PRM system is only required for specific runway or approach course separation. The high resolution color monitoring display, Final Monitor Aid (FMA) of the PRM system, or other FMA with the same capability, presents NTZ surveillance track data to controllers along with detailed maps depicting approaches and No Transgression Zone and is required for all simultaneous close parallel PRM NTZ monitoring operations.

Source: Pilot Contoller Glossary (PCG)