Tail first crash during Autopilot

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Jollyroger

Tail first crash during Autopilot

Post by Jollyroger » Fri Apr 06, 2007 3:35 pm

This has happened to me three times that I know of and at least once or twice to one of our other pilots.
You take off, get the plane to altitude, set the autopilot and leave for a while to do whatever and then when you get back you discover that you've crashed unexplainably or in my case (this time) you discover that your plane is falling, tail first, out of the sky.

This is what I found last night while flying from Phoenix to Anchorage. I wasn't able to catch it in time, (only 120-150ft from the ground), before I crashed.

I have no clue what causes it or anything.

Has this happened to anyone else?


Need my last flight deleted please.

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cmdrnmartin
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Post by cmdrnmartin » Fri Apr 06, 2007 3:44 pm

Don't leave the cockpit :D

Well, this sounds more like a bug in the model you are using, not the flynet client. To the best of my knowledge, the client only monitors the aircraft, it has no direct influence (other than fuel failure) on the a/c.

I would suggest you set your autothrottles correctly, fly at a decent altitude, and don't climb too fast at high alts or you will stall out.

cheers,
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Jollyroger

Post by Jollyroger » Fri Apr 06, 2007 7:49 pm

It's happened to me using the stock 777-300 in the game and using the MelJet 777-200LR

Everything was set.
Flying at 35k ft (Autopilot GPS Nav select)
Speed Mach .84 (Autothrottle)
Engine De-Ice on
Wing De-Ice on
Pitot Heat on

I flew hands on till I was at Alt and then set all the Autopilot settings.
The plane then flew for about 3.5hrs on A/P.
The last check I made of the plane, I was over Vancouver, BC at 35k cruising at Mach .84 with 2 hrs left to fly.
I went away again for another hour. When I came back I heard the Co Pilot yelling and heard the "Terrain! Terrain!" warning. I got a quick glimpse at the Altitude indicator before the crash. I was at 120-150 ft and falling straight down on the tail.

This has happened before, twice, and only when FlyNet starts having connection issues. I'm turning off the tracking setting in FlyNet tonight as suggested by the forums to see if that fixes it.

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Tomb
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Post by Tomb » Fri Apr 06, 2007 8:23 pm

sounds like tubulence has stalled your wings, .84 mach is very suceptable to overspeed which the slow auto throttle pulls the throttles right back, just in time to reach an underspeed condition the autopilot raises the nose, you slow faster and it stalls before sufficant power is applied, the autopilot will keep the nose up untill you are fully deep stalled.

heres another tip if you fly tubo props make sure you dont have full throttle and max RPM because a large overspeed caused by a gust can auto feather your Props to prevent overspeeding the engine, a distinct lack of thrust will result

i dont go more that .75 mach on jet flights i am going to be "out the cockpit " for since the autothrottle wont react fast enough nor much above 31k to avoid engine ice or fuel freezing or being in the stall/overspeed area (coffin corner)

to be safe you need to fly at a speed that gives a 60kt margin up or down if you use real weather, glass cockpits make this very easy, clockwork cockpits its harder, know the plane, the older prop stuff, well you cant get a 60kt margin, its a calculated risk

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SnakeBite
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Post by SnakeBite » Fri Apr 06, 2007 8:48 pm

Well I have the same issue with the stock Boeing 777-300 in FS9 even without Flynet client.. You barely get off the ground and then a stall happens..
I believe this is a bug, however this can also happen to any aircraft if your climb is so aggressive, even with the powerful Boeing 747-400
And for the cruising I use mach 0.82 with real weather applied, and mach 0.76 with the Beoing 777-300

But I dont think this is a Flynet issue, however, I fly offline (Tracker=0)
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Wolfar100
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Post by Wolfar100 » Fri Apr 06, 2007 9:49 pm

I missed the mach .84, myself and Lobo never go above mach .80 in the 777. If you have over stress causes damage checked then your just asking for trouble! :shock:
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vknierim

Post by vknierim » Wed Apr 11, 2007 8:54 am

Sorry to bring this older thread up again, but...

Could it just be, that the client simulated a fuel failure, which shut off the engines? If the A/P remains, active it tries to hold the altitude which it can only do by raising the nose if the airspeed drops. If you are not tin the cockpit at this moment the plane will stall, but the A/P will raise the nose even more to compensate the altitude loss. If you do nothing, the plane will fall out of the sky tail down like a rock...

So I don't think there is a bug here.

It happened to me once in a CRJ. I switched off the A/P to keep the plane flyable and luckily I was able to restart the engines and made it safely to the next airport. My instruments told me that there was a fuel problem, so I assume that the client was simulating a failure.

Greetings

Volker

Jollyroger

Post by Jollyroger » Wed Apr 11, 2007 4:31 pm

Just to clear this up for the masses......

Plane type - 777-200LR
Fuel on board at time of crash - 105kg's (appx)
Speed before crash - Mach .83-84 (at cruise)
Alt before crash - 35k ft.

Plane was on autopilot cruising normal. I left after the plane was at alt, (I wasn't climbing), and the autopilot, speed, course set. Everything was fine. I left and re-checked the plane at least 3x during the flight. The last check was over Canada/Victoria, BC and all was fine. I then left again to eat. When I came back, I heard the Co-Pilot screaming at me. Engines were at full thrust, plane was standing on it's tail just 120-150ft from the deck. Plane crashed in the water.

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