Hi guys,One of things I've been most excited about when looking through this forum is reading questions from users reporting bugs which then turn out to be behavioural quirks built in to the NGX. So in keeping with Captain Randazzo's expectations, I have a question about the autopilot behaviour.I was cruising at 39,000ft on a Ryanair flight between London Stansted and Geneva and I paused the flight while I moved my keyboard to my laptop (whose in-built keyboard has died). Upon re-attaching the keyboard and hitting the 'P' key, the A/P disengage horn went off and the nose pitched violently down to 25 degrees, triggering the overspeed warning and plunging my passengers into a 6,000ft/min descent. I don't know why this happened, but what was interesting was that, once I regained control and went to hit CMD A- a momentary on/off blink of the green 'engage' light and then nothing. CMD B was working fine, but VNAV wasn't engaging at all.My guess is that, what ever happened to cause the sudden dive, I cost Ryanair a lot of money with a broken autopilot! I heard some talk about PMDG simulating the sensitivity of the mechanism in the yoke which disengages the A/P if it's forced, and causes damage if it's forced too much; could this be it?Sincerely,

Yes, probably while paused your controller was moved, or a keyboard glitch during re-connection terminated with a nose down command (confirmed by the plane pitch down). Look in VC if the columns are pushed forward just to confirm this.Maybe related to your keyboard dis/connection.You are the second in few days with an AP failure and consequent airplane dive... The other seems not to be related to this condition, but...

Hi fsgeekI am "the second one" with an AP issue (Hi Andrea :-)In my case the AP looses it when I climb e.g. from 5000 FT to 6000 FT (during the tutorial flight from EGKK to EAM at Leg "DET"). In my case the plane starts to climb quite fast and a couple of seconds later my joystick (I do not disconnect anything like you though) does one strong push forward (as if the AP wants to slow down the climb) and then, 1 - 2 seconds later, the joystick is violently pulled back (as if the AP wants to recover from a dive).I also get warning lights (stab out of trim below EFIS - sometimes yellow, sometimes amber). I can also see on the MFD a yellow (warning?) that - if I recall propperly says "CWS" or the like.During those 3 - 4 seconds, the plane actually does NOT dive - it is not possible to "understand" from a flight-pattern why AP wants to do so. As Andrea suggested there might be an influence from my joystick (Saitek EVO Force) which has FF. I will this evening cut down the FF on that stick by 50% for a start and see if this makes a difference. It somehow makes sense to me that this might be the reason.I don't want to hijack your topic - I just wanted to suggest that you may want to check if you have a FF stick and if you - in this case - want to reduce the FF just for the fun of checking it CheersMichel Bühler

Michel,That definitely sounds like a controller issue somehow to me - if you're seeing stab trim warnings that means something's moving the trim somehow...

Hi Ryan!Thx for jumping in! I actually have quite a large topic "running" regarding this issue. I will tonite try to reduce the FF on my controler and see if that helps. I too have a feeling that this must be the case.Especially because I DO NOT get the issue when I climb manually (means: I turn off VNAV and enter manually in the MCP a climb rate such as 800/900 (Button V/S) and let the plane climb this way. This way, the climb is steadier and smoother and thus the 738 somehow catches up with trimming or so. When I climb by VNAV or by pushing the ALT INTV - Button I get a much steeper climb which then in return somehow busts the AP's trimming and thus he quits his job and tell's me: DO IT YOURSELF FOOL If my understanding is correct, the AP does himself trim the plane while he is "on duty" (I can hear from time to time trimming-sound when A/P is on) - so if you write: "something's moving the trim somehow" I would say: yes, it's the AP who tries to trim while this steep climb but somehow fails... As I do not touch the keyboard nor the controller it must be an A/P input somehow.I will test that. If I don't succeed, I may open a support ticket if you don't mind...CheersMichel Bühler

When autopilot is on the trim is fully automatic, but with AP off there is a condition (low altitude) when the speed trim trims the aircraft if AP is off.However, what Ryan says is that there is a non normal out of trim condition that is strange.I think that you need to solve the FF problem before sending a ticket, this to eliminate the FF from the possible causes (I don't think pmdg have all the joysticks in the world, so maybe possible that they cannot replicate it).Then, when you are ready to send a ticket, I think they will find useful to have a saved flight, I think it must be saved more than 30 seconds before the problem comes on (to let the ngx panel loads).But, now, back to the problem... Have you tried the LVL CHG function? The function is similar to the VNAV climb phase. If the problem is the same we can eliminate FMC from the possible causes.