Hi Traffic, I didn't really wanted to get involved in this discussion but here is my two cent's worth. The optimum config for best accuracy with a GPS RX is having four sattelite signals at 45 degrees above the horizon and one in each direction, ideally N, E, S, W, for an accurate horizontal fix.
For a vertical fix, the optimum set up is one sattelite overhead & three on the horizon, ideally 120 degrees apart in azimuth. This is impossible to achieve inside the cabin of an aircraft. Stick to the Airshow, it's much more accurate. Cheers, HD.
Old Smokey, QNH and teperature have nought to do with GPS.