Wide area multilateration (WAM) is a cooperative aircraft surveillance technology based on the same time difference of arrival principle that is used on an airport surface.
WAM provides performance that is comparable to secondary surveillance radar (SSR) in terms of accuracy, probability of detection, update rate and availability/ reliability.
Performance varies as a function of the location of aircraft in relation to the ground sensors.
Update rates and probability of detection can be tailored to various applications such as precision runway monitoring (PRM), terminal maneuvering area (TMA) and En-route surveillance.
Operational implementations include the U.S. Western Colorado and Juneau, Alaska, areas and the Innsbruck, Austria, region.