717 autopilot issue

[jghastings]

Hi all,

I was just attempting a flight from Hervey Bay to Brisbane in a QantasLink 717, the first time I’ve flown that jet in a while. After passing through 10,000ft I set the autopilot to climb to FL180, and then turned away to do some work. When I looked back the plane was topping out at FL320, and thereafter my attempts to get it to descend had some seriously bizarre impacts. If I set the VS to descend, it climbed, and vice-versa, but not to the magnitudes of VS I was setting in either case. Is this a known issue?

While taking manual control to try to force the darn thing back down, it went into reverse tornado mode and I soon aborted before it could start plummeting at Mach-something into the Pacific.

Thanks,
Jon

[Plane_Masta]

That is strange. I never really had any problems with the 717

[Chris_S]

I have seen this where people set the altitude but they dont press it and turn it orange to turn it on.

Do you have any screen shots? Otherwise see if you can reproduce it.

[Plane_Masta]

reverse tornado mode

Do you mean like it started reversing?

[Chris_S]

I think they mean spiral down.

[jghastings]

No, I definitely had it all turned on. I sat looking at it for a while thinking “what the hell is going on here?” before trying to start doing something about it. As I said, it was moving in the opposite direction from what I was setting the VS to be, and indeed for a while it looked like it was trying to correct itself by descending. Alas it wanted to do that at 4,000fpm, and I couldn’t seem to get a handle on how to get it to do something logical so that it wasn’t randomly climbing or trying to descend far too quickly. When I disconnected the A/P it all then went truly downhill.

[Chris_S]

Unfortunately there is nothing we can research unless a video or something is provided.

Also remember that you need to re-calibrate before turning off AP in case your device has changed positions. This can cause it to nosedive as well.

[jghastings]

Well, just tried the flight again to see if the same thing happened, but this time it was fine. Who knows what was going on before, but there we go.

I will try to remember to do screenshots if anything weird happens in future (not that I expect it to). I was just a bit fixated on trying to solve the problem when it was happening.