Originally Posted by
Lon More
Most centres now use Multi radar tracking as well, PRI returns may be a bit "fragmented" for want of a better word, and correlation lost. As ATC Watcher said, we had the luxury of continued tracking, but I wouldn't habe been happy with say 10 aircraft in the same predicament in one sector. A greatly increased workload and no real guarantee that the tracking continues.
ATC Watcher, we used to be given a contact number to call if this happened; ENDEX. Is this still so?
You are both almost right.
IFF the secondary response which is the one that is linked to the flight database is correlated to a primary THEN when the secondary fails the correlated primary will still carry the 'label' that the secondary response was given.
However, if you lose secondary radar before the aircraft is in primary cover the subsequent primary response will be uncorrelated as there was no secondary response. In some systems it is possible to identify the primary response and manually correlate it with a known aircraft from the flight database, but not many allow this.
I would think that an almost immediate ground stop would be put in place if there was a continuing failure over a significant area. Those flights airborne would be back to procedural control.
I have my doubts that it was a military jamming exercise as that would have had considerably greater effect. However, if it was there are normally extensions to call or transmissions that can be made on guard frequency to tell them to desist immediately.