Autopilot Disengaging

Hi everyone, just need some clarity on what causes the Auto pilot to disengage, i flew from KORD enroute NZAA, i woke up in the morning only to find that my aircraft had crashed. I went and reviewed the flight details and this is where i found that autopilot had disengaged. After 14hrs of in flight it disengaged what followed was the aircraft banking all the way to the right turning backwards and the rest were series of events which lead to the crash and obviously resulting into a violation.
I was flying a B789 at FL320 and had heavy head winds unfortunately it doesn’t show the wind speed on the replay. I had loaded about 17hrs of fuel on departure seeing that flight was going to be bumpy.
Could this be as a result of headwinds,
Fuel etc?
Thanks in advance for your responses

Your fuel could of definitely been a factor if not the factor. When you lose fuel and your tank is empty, your engines shut off resulting in insufficient airspeed to maintain the altitude you have set. Your autopilot despite the insufficient speed tries to correct for that but only makes it worse but pitching up to maintain the altitude you have set which then results in a stall and the autopilot parameters being exceeded so then it disengages. You are just in a nose dive from there if your not at your device. Heavy head winds can definitely change your flight time to the airport. Be sure to plan the winds along your route so you can take extra reserve fuel if needed.


Thanks @Asher that could most probably be the reason, that’s what i thought of first but realised that i had taken 3hrs of extra fuel. With heavy winds i presume then that all tbat extra fuel burnt out.

You can actually hear if that was the cause in the replay, since you should be hearing the engines spool down a few minutes before you drop out of the sky :)


You could’ve also flown too high for your weight, stalled and crashed!

I mean it happened 14 hrs along the flight so if it managed that long I don’t think that’s the case.

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Ah ok. Check the replay and you should see what happened.

Fuel seems to be the most likely cause although I think it’s interesting because normally you get approximately a 1:1 ratio of projected to actual flight time in the 787, even cruising low at FL320.

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I will listen to it once i have completed my overnighter, thanks @schyllberg

Nope not at all

Thanks @AndrewWu will chat to you on slack later

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