Originally Posted by
ZOOKER
arearadar, (post 10,218), has raised a very valid point about how the aircraft was re-identified using primary radar. In the U.K, as far as I am aware, there are only 4 ways of doing this, and none of them could be employed here.
Military radar units may of course have other available techniques, unknown to civilian ATCOs.
It all depends on other traffic.
If you have a tagged primary return without any secondary/ADS that flies into your overhead at a steady speed and track, and at the expected time (probably less than a minute) a primary only return appears flying out of th overhead at the same speed and on the same track and there is no other traffic around, then it is a reasonable assumption that it is the same aircraft. If the airspace is alive with maneuvering primary only traffic and the one that you have tagged is randomly changing heading and speed and disappears together with several others into your overhead - you have a different problem.
I would suggest that it was the former that was more likely at 2am that morning. It may also be that it was being 'watched' by other radars that nobody wants to talk about, so the radar shown is one that is well past its sell by date and can therefore be admitted to.