HI,I have just encountered what must be the quickest flight level change ever. I was flying along at 370 when all of a sudden all #### broke loose. My aircraft showed as being now at FL400 and speed was well over 500!! I disconnected autopilot and hand flew for a few seconds, when suudenly I'm at FL320 !! This all in the space of a few seconds and the aircraft showed no signs of descending, it was as if I had used the slew option.I disconnected ASV and used vatsim weather instead through SB3 and all settled down.This obviously seemed to be related to ASV. By the way I have wake turbulence turned off so it was nothing to do with that.Any ideas guys.RegardsDrayton

This doesn't sound like anything to do with ASV, but more likely has to do with corrupted pressure data. It would also explain why things settled down when you used an alternate data source.You are cruising at a constant 29.92 pressure level. Assume the pressure is 29.90 and the next update reads in an altimeter setting of 30.90 (should be 29.90), the aircraft will suddenly zip up in altitude to compensate for the drastic pressure level change.Bruce