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How far above Vs should the stall warner operate?

I think the Socata one goes off about 10kt above Vs…

Administrator
Shoreham EGKA, United Kingdom

I prefer something more like 5 knots. Passengers don’t like the surprise of the shrill sound just after liftoff and during the flare…

Last Edited by boscomantico at 04 Apr 07:48
Frankfurt (EDFZ, EDFE), Germany

It is regulated in FAR 23.207 (for FAA certification, I don’t have the relevant EASA document, but it will be similar). Minimum is 5kt above stall speed, however “sufficient time” must remain after stall warner activation for the pilot to react to the warning. So high-drag and/or low power aeroplanes might require a wider margin.

EDDS - Stuttgart

Minimum is 5kt above stall speed, however “sufficient time” must remain after stall warner activation for the pilot to react to the warning. So high-drag and/or low power aeroplanes might require a wider margin.

Yes, I’ve noticed that variation, apparently for that reason, and also some differences between manufacturers. Cessnas seem to have stall warners that come on a few knots above the actual stall, and actually do function as a warning that you’re about to stall the wing. Conversely some higher wing loading planes provide much more warning. The design philosophy in that case seems to have been to prevent the pilot from getting too far to the left of the drag bucket, in a high power, high sink situation on final. I guess that makes sense if the plane was sold for use by students etc, but has a somewhat high wing loading for that role.

I learned how to fly with no stall warner so it’s interesting to see the differences. I like something like 5 kts better than 15 kts, and I’d prefer to be able to disable the horn with a switch. A friend has a factory built, certified Pitts S1 that was by regulation fitted with a stall warner – not very helpful for an pure aerobatic plane, so for that and some other reasons the plane is now in FAA Experimental Exhibition with stall warner disconnected.

Last Edited by Silvaire at 04 Apr 15:00

In the Pilot’s guide and POH of my Tomahawk, it says “between 5 and 10 knots”…. So it’s not very accurate! But I would prefer 5 knots also :)

Military aircraft were never fitted with stall warners!

Military aircraft were never fitted with stall warners!

That’s why more of them get lost during training than during combat…

EDDS - Stuttgart

Why should any pilot want a stall warner?

Like stalling practice, waste of time, training should concentrate on watching airspeed (wont fly without it).

You should always have one eye on the ASI, thats all that you need.

If you hear a stall warner at any time other than landing you should get some more training!

Like stalling practice, waste of time, training should concentrate on watching airspeed (wont fly without it).

Aispeed indicators do fail from time to time (happened twice to me so far). Eyes are sometimes urgently needed elsewhere than on the ASI, e.g. outside in a busy circuit. So a stall warning device that is independent from the pitot static system as a safety net is not such a bad idea. Mind you, transport category aircraft that must be flown by two professional pilots must be equipped with such a device.

Last Edited by what_next at 04 Apr 21:04
EDDS - Stuttgart

And of course there’s no such thing as a ‘stalling speed’.

Going back to the Tomahawk, if you select alternate static inadvertently you gain an extra 10 knots IAS, which is enough to get you very slow in the circuit. First of all, the stall warner is a very nice backup. Secondly, even without the stall warner I could tell that the ASI was over-reading and rightly added an extra 5 knots to my circuit speed because… it just felt like the right thing to do.

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