Originally Posted by CashKing
Especially in cities, where dead reckoning is deployed more often than in open space due to gaps between buildings or tunnels, stops at traffic signals can be used for this purpose. Deviations are thereby reduced.
Hey, impressive stuff. Next time I'm flying through a tunnel or have to stop at a traffic light I'll remember my FMC is in DR mode.
Pasted text from a web site about car navigation systems notwithstanding, I expect that Kalman filter algorithms are used in FMCs when combining data from multiple sensors (gps, dme, irs etc.) to generate a composite FMC position. Not sure about the relevance to GPS per se?
As to the original question, GPS cannot provide heading. It can only provide track and then only when moving. An AHRS can provide true heading, so you really need combined GPS / AHRS to be independant of the earth's magnetism. When all aircraft can have a combined GPS / AHRS costing less than current instruments we may see a switch to true navigation.