hyperveloce,
GPS reception
Yes, if the GPS reception antenna is accelerating relatively to the line of sight of the emitting satellite (being tracked, with others), the demodulation of the GPS spread spectrum signal (hence the SNR) can be further degraded.
Jeff
Not on any GPS set I worked on. That level of tracking, particularly with an aided GPS, is built into the beasts. An extreme example of aiding performance is in dog fights. The GPS sets lose lock only briefly and bring themselves right back in using the aiding as a clue for likely loop errors.
Military sets do have a slight advantage due to tracking the higher rate P (or Y) code channel. But they need it for jets that can pull 7 G moves. A relatively normal commercial plane's accelerations are not going to give any decent GPS set any particular problem. This is what high order tracking loops are for.
Of course, if the IRU aiding is lost then GPS can become sketchy until the aircraft dynamics settle down. Then it becomes as accurate as before.
Are you, perhaps, referring to a different problem GPS has? It tells you where you were and when you were there. It does not tell you precisely where you are now if you are moving or accelerating. Of course, in usual cases this error is smaller than you need to consider.
JD-EE