"Kurt Ullman" wrote in message
nestork wrote:

Modern radar is sophisticated and might be able to tell the difference
between one plane or two located very close together. You'd need an
expert, like an air traffic controller, to provide an educated guess
here.

From talking with a friend who is an ATC about this in another
context said that would be very dependent on the strength and type of
radar, how close it is, and other obvious factors (not the least of
which is the attentiveness/skill of the ATC). So, especially at the
outer ends of the range, it could happen.

It used to happen all the time - that's why they went to using transponders
to provide ID info next to the blips on the radar screen. I believe the
hijackers bet on the fact that at 1AM everybody, including the observers in
the military radar stations, is a little bit sleepy. They certainly knew
where to "fall off" the radar screens - at the handoff between Malaysia and
Vietnam.

--
Bobby G.