With all due respect, that is because you don't understand the technology involved. The proximity of the radar returns in a passive system is irrelevant and the PASSUR system doesn't assign any ID's. It simply reads what is transmitted to it. The "radar" (it is really only a receiver) can only see what is sent to it. And what is sent to it is a very specific signature that provides very specific information about the aircraft carrying the transmitter. All commercial aircraft now fly with a similar system (TCAS) that is used to prevent midair collisions. It relies entirely on the same transponder transmissions and is incredibly precise at fixing aircraft positions. But it can only "see" what is transmitted to it, and cannot display anything else.
Ditto!!!!
I'm somewhat familiar with IFF transponders because many years ago I was trained as a Hawk Pulse Acquisition Radar repairman. Are you saying that Air traffic control uses only transponders, and not regular radar as well? At the time, we used a radar system that showed transponder returns as brighter dots on the screen. If there was a transponder in the target, it was a friend. If there wasn't, it was a foe and you would shoot it down.
By today's standards that was primitive technology. But are you saying that air traffic control uses only transponders, and no accompanying radar as well that could paint the side of a plane or missile? Wouldn't that mean that if someone in a light plane, for instance, strayed into the traffic pattern, you wouldn't see it?
If you were using both radar and transponder returns, then it seems conceivable that the radar could confuse an object close to a plane but without a transponder as the plane itself.
Sorry pal but I read ALL of the info on the PASSUR web site. PASSUR uses the return information but is also fed info from the ASR. In the event that the ASR returns a signal (ghost or not) PASSUR thinks it has to assign a designation to it (I believe - computers doing what they think is correct). Clearly evident by clicking on the icon on the dual radar track from PASSUR - the FAA ATC tapes may not have designated the bogey as the AA flight. By your explanation the bogey return the same IFF codes as the AA flight at least as far as PASSUR was concerned. How could that be? TCAS is NOT implemented on ALL commercial aircraft. ONLY those with FAA oversight. Many foreign freighters and other aircraft do carry TCAS. Also, it is entirely possible that this was another aircraft that wandered into the airspace with it's IFF turned off. I can turn IFF off on my plane anytime I want. Is it also possible that there a drug runners who have IFF spoofing capability (unlikely a 13:00 in LA but if the money's right)? EA-6B's can do it with the flip of a switch and they can return the appropriate radar signature for any aircraft they want. Did the AA pilot report a TCAS warning? I have not heard that if he did then the whole thing is probably just one big snafu.
Well, I am an optics guy, not a radar guy, but let me ask a question.
Is it even remotely possible that the "second object" seen is a reflection of the transmission from AA 612 being bounced off some other object in the vicinity of AA 612?
This would explain both why the second object had AA 612's identification, and how a non-transmitting object could be seen by PASSUR.