Well, yes and no. Please keep in mind the distinction between "primary returns" and transponder information, and between civilian and military radars. What ATC uses for the most part is transponder data - that is, the little box next to a blip that contains identification information about the aircraft. Depending on what part of ATC you're talking about, that will include flight number or registration, a/c type, speed, heading, altitude, etc. HOWEVER, when that system is not available (i.e., it crashed), ATC has to use so-called "primary returns", which are what the rest of us call "blips". And on *civilian* radar, all blips are pretty much equal, and include false returns like trucks, boats, birds, and weather. The aircraft metadata is then kept on a backup computer system and/or the paper-strip system. Then there are military surveillance radars of various sorts (primary, IFF interrogator, phased-array [PAWS], over-the-horizon backscatter [OTH-B], etc.), used for air defense and for tactical air control. On those, all returns (blips) are *not* the same; that's where stealthiness comes in. The art of stealth aircraft design is to reduce the radar profile of a large plane to that of a small plane or a bird, or disappear completely. An air defense radar (ours, anyway) can definitely distinguish a 747 from a Cessna. I worked on PAVE PAWS and OTH-B, back in Cold War days, on the communications networking part. -- Michael C. Berch mcb@xxxxxxxxxxxxxx On Friday, December 5, 2003, at 05:26 PM, Floridasky@xxxxxxx wrote: > A radar blip looks exactly the same for 747 and single engine Cessna. > Believe > or not flock of migrating geese will appear like an aircraft. In South > Florida controllers call possibel traffic for semi trucks on I 595 on > occasion not > know for sure what it is. You can observe ships just off the coast on > radar at > times also. They all look an aircarft hit. > > Mike (MIA) >