In a message dated 04/11/2006 18:49:42 GMT Standard Time, bones@xxxxxxx writes: Sorry for the slow reply Frank - been ripping this PC to pieces today to get at a failed Northbridge fan.. Thanks Bones, I will print out your reply and refer to it while I program the AP switching. The bit about leaving the YD on, even when you change planes, could lead to problems. I intend to have a YD switch anyway, which should resolve this if it ever happens. I do recall problems with the AP giving priority to a too ambitious climb rate leading to stalls, I don't think I can fix this with a gauge as I'm assuming its part of the FS functions. I must make a note to test this in FSX. I recall getting around it previously by editing the default climb rates in the ?aircraft.cfg? file. I did some more work on the AP today and I now have another question I'm afraid. I'm confused as to the difference between Autothrottle and Airspeed Hold. I think that you cannot have an Airspeed Hold without an Autothrottle, but why have 2 variables? Or is this down to the different AP types? Frank T.