UK's first multilateration
NATS has commissioned the UK’s first wide area multilateration (WAM) radar system at Edinburgh Airport.
This first operational use of WAM for an approach service at a UK airport has replaced secondary radar as the terminal area surveillance source for aircraft separation.
The WAM system - supplied by Saab Sensis - provides air traffic controllers with the precise surveillance needed for the separation of arriving and departing flights.
Rather than using large rotating radar assemblies, multilateration uses multiple low-maintenance, non-rotating sensors to triangulate aircraft locations through time-of-arrival of transponder signals - to give precise aircraft position and identification.
This gives a higher update rate and greater positional accuracy than traditional secondary radar, using a minimal number of simple sensors for a less complex, lower life-cycle cost system. Additionally, the sensors support Automatic Dependent Surveillance - Broadcast (ADS-B).
Until now, Edinburgh Airport had been using monopulse secondary surveillance radar (MSSR) for terminal area surveillance - but it was approaching the end of its serviceable life. After weighing alternatives, NATS identified WAM as the best technological and economical replacement.
Saab Sensis notes that almost 100 sites worldwide have chosen their multilateration for airport surface surveillance and management as well as wide area surveillance - and it could easily be expanded into a wider surveillance network for en route coverage.
It should be remembered that, unlike primary radar, all of these secondary systems - WAM, SSR, ADS etc - are 'dependent', in that a responder must be turned on and working in the aircraft for it to be tracked.
Details from NATS and Saab below.