True, but given the way the ATC or TCAS receivers work, they really care about the history of the echos.
They are looking for a vector. It would be theoretically possible to create a ghost, give it a speed and heading to make people avoid it. But I'm not sure what it would achieve. Maybe I'm not being creative enough.
Thing is though, why would that be any different to "FY holding London NDB UFY 60 descending 40." on the radio. If you then dropped off the radio completely a massive poostorm would happen as ATC tried to figure out who that transmission came from. Whilst ATC have to try and find the plane that thinks it's got full service in class-a space (non pilots this is the busy bits of sky where you have to get permission from guys on the ground) they would divert away from that area.
I'm not aware of a TCAS system which doesn't alert the pilot to the fact it is changing the autopilot heading. If this happened in busy controlled airspace, it would have to be with acknowledgement from ATC or the pilot would at worse do a near miss to avoid a phantom that wasn't there, he certainly wouldn't hit one that was to avoid a ghost which ground wasn't warning him of.
If you're over the north atlantic and the TCAS wants to change heading or attitude, it will alert the meatbag AFAIK.
History is a good point, but does TCAS really care? I thought it was a fairly simple device in that regard. It has only vague directional sensing.
As for twiddling the autopilot and acknowledgement with ATC, I'm not aware that either is the case. TCAS simply informs the pilot, and current systems never advise any horizontal maneuvers, only climb/descend, because their ability to detect horizontal position is fairly crap. A TCAS advisory takes precedence over ATC commands and is expected to be obeyed immediately unless there's an obvious immediate danger to doing so. You never inform ATC of the TCAS alert and ask what to do, you always obey the machine, then tell ATC what's going on when you have time. If ATC notices the impending collision and gives you instructions that contradict the TCAS's instructions, you follow TCAS and ignore ATC.
They are looking for a vector. It would be theoretically possible to create a ghost, give it a speed and heading to make people avoid it. But I'm not sure what it would achieve. Maybe I'm not being creative enough.
Thing is though, why would that be any different to "FY holding London NDB UFY 60 descending 40." on the radio. If you then dropped off the radio completely a massive poostorm would happen as ATC tried to figure out who that transmission came from. Whilst ATC have to try and find the plane that thinks it's got full service in class-a space (non pilots this is the busy bits of sky where you have to get permission from guys on the ground) they would divert away from that area.
I'm not aware of a TCAS system which doesn't alert the pilot to the fact it is changing the autopilot heading. If this happened in busy controlled airspace, it would have to be with acknowledgement from ATC or the pilot would at worse do a near miss to avoid a phantom that wasn't there, he certainly wouldn't hit one that was to avoid a ghost which ground wasn't warning him of.
If you're over the north atlantic and the TCAS wants to change heading or attitude, it will alert the meatbag AFAIK.