Red,
Thanks for that! Not much use, but at least I now know what it is! Maybe if I had asked the right person, I could have got the answer first hand! If this is correct, why is it that the maximum figure you can put in is .5M, and the minimun is .3M? Is this based on some FW logic? This however does not explain why it was that one of our aircraft lost its ability to ascertain its groundspeed in the descent when this particular number was set to the default 150/.-M/3.0 . Put the mach no. in and all of a sudden it knew its groundspeed. Is it trying to work every speed out as a mach no?
