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Stall Question

Posted: Fri Jul 18, 2014 1:23 pm
by vololiberista
If anyone can remember!!!
Is the AP dosconnected at the stall or at the stick push?
vololiberista

Re: Stall Question

Posted: Sat Jul 19, 2014 12:21 pm
by 1103
At a guess I would say the a/p would disengage at stick push because the a/p input is being overridden.

Paul

Re: Stall Question

Posted: Sat Jul 19, 2014 10:52 pm
by Jelle Hieminga
I agree with Paul, just wanted to add that the stick push will prevent the aircraft from entering a stall. So your first option would never occur with a functioning stall identification (stick push) system.

Re: Stall Question

Posted: Sun Jul 20, 2014 2:45 pm
by vololiberista
Thanks Guys,
That was my guess. Though Jelle the 10 has a stall warning and then a stall identification. (the two lights on the extreme left of the Captain's panel). So the stick pushes at the ident which is in effect stall onset. So it prevents a full on stall for sure. The scenario would be the AP on altitude hold (desperately holding on to it until the last moment). Of course the crew would be well aware of something being awry(as long as they weren't trained by AF :-)////) ). Lack of wind noise - sloppy controls (under AP control the AP would be seen to make larger and larger corrections).

What amazes me though is how they managed to get the 10 to drop the nose in a stall thus avoiding the super stall characteristics common to T tails. Very clever aerodynamics.

Re: Stall Question

Posted: Sun Jul 20, 2014 5:07 pm
by Gwyn
Having had the stick push demonstrated on my initial training I can assure that there is no way the a/p would remain in. The stick literally leaps out of your hand to bring the nose down and safety.

Re: Stall Question

Posted: Sun Jul 20, 2014 5:31 pm
by petet16
You also have the stick shaker, which is kind of difficult to ignore, and as said above the stick push will be far stronger than any attempt by a pilot to hold the stick back.

Re: Stall Question

Posted: Sun Jul 20, 2014 8:20 pm
by Gwyn
got it in one!!

Re: Stall Question

Posted: Sun Jul 20, 2014 9:49 pm
by Tonkenna
Theoretically you should (with some considerable force) be able to override the push if you so wished, but if it took you by surprise I doubt you could... I tried in the sim and could hold it just hold it... but I was expecting it!

Tonks 8)

Re: Stall Question

Posted: Mon Jul 21, 2014 1:44 pm
by vololiberista
I sometimes wonder how in some cases pilots seem to totally ignore a stall warning. And in the case of G-ARPI they turned the stick pusher off [-X

One's reaction to a stall should be instinctive. It's much better to go with it and then if the a/c isn't doing what is expected decide whether the warning is false.

Re: Stall Question

Posted: Mon Jul 21, 2014 2:28 pm
by Gwyn
All very well in theory but in the heat of the moment............

Re: Stall Question

Posted: Mon Jul 21, 2014 7:18 pm
by Tonkenna
There were times when it was important to turn the system of... e.g., during receiving. I can certainly vouch for the fact that indications can be very confusing at times when things happen unexpectedly and in the heat (and terror) of the moment, well, it can be difficult!

Tonks --+0+--

Re: Stall Question

Posted: Mon Jul 21, 2014 8:08 pm
by vololiberista
Tonkenna wrote:There were times when it was important to turn the system of... e.g., during receiving. I can certainly vouch for the fact that indications can be very confusing at times when things happen unexpectedly and in the heat (and terror) of the moment, well, it can be difficult!

Tonks --+0+--
The difference Tonks is that for service reasons it was turned off. While it is off therefore, the crew (hopefully) would have hightened awareness of a stall risk. That is somewhat different to say normal operations when perhaps the stall warning goes off unexpectedly plus stick pusher etc., (unexpectedly because the crew were not paying proper attention and were caught unawares). To then disregard the warning and turn it off would be wrong. The stall protection systems are much more reliable than unreliable and to constantly disregard them by disabling, effectively makes the stall protection the most unreliable piece of equipment on the aircraft which is a nonsense. Doesn't it have to be written up in the aircraft log?

Re: Stall Question

Posted: Mon Jul 21, 2014 8:27 pm
by Gwyn
In BOAC/BA we actually dumped the stick push below 1,000ft AGL during T/O and LDG.

When I was at Duxford on 'GC' with a DAS rep I told him about that and he was very grateful since he had pretty well covered all the bits and pieces but this red lever next to the Fuel Cocks had totally mesmerised him until that moment.

Re: Stall Question

Posted: Tue Jul 22, 2014 8:33 am
by Stewart
vololiberista wrote:I sometimes wonder how in some cases pilots seem to totally ignore a stall warning. And in the case of G-ARPI they turned the stick pusher off .
Not only that, they had already turned the AP on which seems to be seldom mentioned and was normal BEA operating procedure at the time, and almost immediately after this they changed to turning it on only once at a safe altitude had been reached had they actually been flying the AC they may have realized what was occurring earlier. BOAC on the whole never engaged the AP anything like as early although I believe an order went round the fleets in a similar vein as BEA order after this accident

Re: Stall Question

Posted: Tue Jul 22, 2014 3:24 pm
by vololiberista
Gwyn wrote:In BOAC/BA we actually dumped the stick push below 1,000ft AGL during T/O and LDG.

When I was at Duxford on 'GC' with a DAS rep I told him about that and he was very grateful since he had pretty well covered all the bits and pieces but this red lever next to the Fuel Cocks had totally mesmerised him until that moment.
For obvious reasons!!! :D
At those heights the stick push would leave you pointing directly nose down probably. Mind you it would be quite a fuel saving on flights to Australia :lol: