familiar with B737 FMS?
 

is it true that - regarding initial position errors -
the fms would not accept pilot's false latitude and longitude entries?

I thought it could only identify false latitude!

It can sense the latitude directly, so it wil reject a false latitude. It will compare entered longitudes with the last known postition, and query any difference, but you can eventually convince it that you know best (even if you don't).

Modern ones have GPS to check against as well and it'll get annoyed at you if they are out by a great deal. As previously said though it is possible to convince it and turn off the left and right GPS. Not sure why you would want to but hey.

^^^^
Todders knows, hes clever like that.......:p

thanx so far,
sorry more questions arising,
will open a new thread