Instant stall and fall out of the sky

Device: IPAD
Operating system: IOS

Good morning,

Ive been having a recurring issue with 777-300ER. On multiple occasions ill be flying along with no issue then out nowhere the plane will pitch violently and then stall, followed by nose diving into the ground. This has happened 3 times flying to or from EGLL. I dont know 100 percent if its a sim issue or an IFassistant (3rd party app) this issue has only recently been happening. There is video proof of the incidents on my logbook replays.

Thank you

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Can you share the replays - those will be able to give us more info as to what exactly is happening.

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Stupid question how do I do that

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@Trumpeteerjones Save the replay into your files then upload it into this link once it uploads copy the link and send it to us

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Here’s the link

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Feels like this issue, yet not as provoked.

What were the winds like? Any sudden changes? It does seem quite random to me

It seems like you were on a turn similar to the topic above

I didnt catch the winds at time of crash. If the replay could show what fixes i was between i could near the problem down to IF or the third party app ( IFAssistant). On the 3rd party app you can set a step altitude for certain fixes and i wonder if thats the problem. Sadly i cant tell cause the map on the replay doesnt show the fixes

No, I really doubt it was the VNAV, I don’t think you were climbing

I wasnt climbing yet…my cruise was FL330 with step up to FL350 at HASOS. What the IFassist app does is allow you to set those altitudes in the fltpln on their app and it will then move the plane up or down depending on the altitude programmed in. I usually use this feature if im going to step away from the sim for a bit.

My best theory would be that there was a sudden increase in the tailwind (also due to HDG change), leading to the plane going unstable, trying to correct it, but overcorrecting. Similar to the topic above. The IAS also went down by a bit which I’m assuming the AP also tried to correct, but mixed with the winds it got all messed up and lead to a stall.

The point marked X shows were this happened and it would support my theory. Even so, the AP should be able to handle such situations…

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From my experience, the IF’s AP doesn’t seem to handle much…

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After reviewing the replay, I’d say it’s most probably an issue with IF-A’s step-climb feature you mentioned. At 01:20:15, your altitude was increased from 33,000ft to 35,000ft in the A/P, and your A/P V/S Target went crazy - from +216fpm, to -400, to +400, to +1,500, to +1,900, to +221, +100, +800, +1,200 and it kept bouncing up and down, until it reached a maximum of 6,600fpm, and a minimum of -7,200, following which your autopilot disconnected, as it all happened extremely quickly - all in the span of 16s between the start of the climb and the loss of control and autopilot disconnection. Since the autopilot was trying to follow the target V/S, it had to make pretty severe control inputs, which destabilized the aircraft and caused it to lose control.

The odd values (216, 221) help back up my theory, as users cannot set these vertical speeds themselves - they would need to be fed externally, through a third-party app or VNAV. Since VNAV is unavailable for climb natively, the clues are pointing to IF-A.

In any case, I would advise against performing altitude changes while away from the device - there is a chance you might climb into traffic above you, or that something goes wrong during the climb, as it evidently did here. In the future, to prevent your flight from being ruined (and maintaining more professional conduct on the Expert server), simply perform altitude changes only if you’re at your device and you can supervise them. Better safe than sorry, at the end of the day!


Thanks for looking into the issue. I appreciate it

I wasn’t sure what the wind was in my flight. But it was quite a heavy turbulence before I went afk. I was using IFAssistant but not the step climbing mode. Given that his case was similar to mine, it may be caused by the same reason (or not).

It appears that your heading setting was turned off and the plane started to turn which caused the uncontrolled descent.

Well i just did 2 flights KLAX-EGLL-KMIA without using the IF-Assistant for altitude steps and the floghts were both fine. So it is the the app ill give the developer a ring and let them know.

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