sudden steep dives

[Guest henkb]

Hi, just upgraded to the latest version and have done 2 flights now. In BOTH flights, I experienced something strange. Just cruising along, nothing out of the ordinary and then suddenly the plane would go in a 4000 fpm dive. VNAV got disconnected, ALT was still set at cruise level and Autopilot was still connected. Still, a dive. Had to switch off autopilot & autothrottle and tried to get her out of the dive. First time it succeeded, 2nd time the overspeed was too much and the airframe overstressed. On the 2nd flight it happened once at cruiselevel and the 2nd time was at 4000 ft during the approach. That's not much air between my plane and the hard Dutch soil, I'll tell ya... Anyways, anyone seen this? Btw, I was using the -800, VC version.Thanks!

[crvm 0]

Well if I put on my swami hat and take a best guess I would think that 1] You have forcefeedback on your joystick and with wind etc with kick the A/P into CWS mode causing this dive.2] If not force feed back then pehaps you have touched the controls which one never does with the A/P in command otherwsie this too causes reversion to CWS modes.3] If you look at the pilot's flight display you might see a yellow CWS P on the FMA which will tell us 100% what mode the aircraft is really in. Do not always go by the MCP lights, in fact pilots are taught to look too the PFD for correct modes engagement.Best Wishes,[h4]Randy J. Smith[/h4][h3]P M D G's 747-400[/h3][h4]coming to a runway near you[/h4][/font color]Caution! Not a real pilot, but do play one on TV ;-)AMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | Maxtor 6Y080M0 SATA 80 GIG | 512 DDR 400 | Windows Xp Pro | Windows Xp Pro 64 |

[rsrandazzo 6,353]

Henk-Something else to take a look at and consider:Have you changed the aircraft loading at all? (anything other than fuel?)We have had a few users run into "departure from controlled flight" and it turned out to be the result of making manual changes to the weight and balance of the airplane outside of the PMDG Weight and Balance Manager.... If we see this- it is MOST often related to a joystick that is out of tune and sending spurious commands to the AFDS, however... Randy is spot on there...

[Guest henkb]

Randy/Robnope, no force-feedback gear installed here.I didn't change the load balance either. I used the fuel planner from the PMDG website to 'read' the payload (23000) and boarded the fuel by the push of a button as well. (18875 lbs). Didn't touch the yoke, but will recalibrate to be sure it's not doing something strange.Thanks for the input guys - will keep an eye on the PFD and will also make sure that any changes to the weight/balance are made with the balance manager.take care

[rsrandazzo 6,353]

Henck-Couple of other things to look at:Are you using a weather generating program? If so, which one? There was a period where we found that severe changes in weather conditions/winds caused by some popular weather generating programs would cause the type of upsets that you experienced.Also- any chance of an overspeed/overstress causing an MSFS induced "crash?" Technically our airplane should prevent you from overspeeding the airplane if on A/T- but it's worth asking...(Ah- the joys of post crash analysis in the sim world...was it a code problem? or was it user error? Shouldn't we get a year to write a final report? :-) )Keep me posted, Henk. We are not getting any other reports of similar behavior to tech support- so I'm confident it is localized- which also means we'll help you track it down....

[Guest spike]

Hi, I had the same thing and found the cause to be touching the joystick, in my case useing the hatswich or even nocking the joystick would cause the AP to change to CWS, I have the Force Feedback 2.Spike :-)