Instrument Training - Detecting a Stall

[arrow203]

I'm working towards my night rating with an instructor at the moment, and as part of it, I've been performing some simple straight ahead stalls while "under the hood."

I admit I must have gotten rusty at performing stalls since completing my PPL, as I'm having some trouble detecting when the airplane is fully stalled. This particular airplane seems to have a very light wing buffet that I'm having a hard time feeling out. What else should I be looking for? Which instrument should I expect to react first to indicate a stalled condition - VSI or altimeter? I know I'll iron it out with more practice, but would like to go into my next flight with a refreshed sense of the process, as this is clearly something that's slipped in my skills.

Thanks,

[trey kule]

let me get this correct.. You are doing the instrument portion of a night rating. and your instructor is doing stalls under the hood? did I get that correct?

Is this a required exercise, or is this another case of an instructor who has decided what is necessary (or fun) for proper training. How much time did you spend in recognizing the approach to a stall in all configurations, and recovering before you stalled? Did your instructor emphasize first that if your airspeed is deteriorating, you had better take some sort of action...Or was that bypassed to go straight to the actual stall?

In the five hours that is required for the night rating, you should spend getting comfortable on instruments so that if you ever advertently run into cloud at night (and it happens), you can fly the plane. This is not fun for instructors. So it tends to be overlooked for stuff that the instructor likes to do, and they are very good at rationalizing it.
It may not seem that you are learning anything humming along straight and level or just tracking in and out on a VOR or ADF, but you are getting comfortable with you scan and how to fly on instruments.. Way too many instructors dont understand this and want to do fun stuff.
But then again,
maybe the standards now require people to do stalls under the hood for the night rating.. Which I suppose makes perfect sense if you are not going to allow the student time to just fly on instruments to get relaxed and avoid unusual attitudes.
To answer your question ....you are flying on instruments...What are the indications to an approach to a stal?
Learn those. And take the necessary corrective action before you stall...
Are there not stall warning horns or lights in your aircraft? Oh wait...they just tell us when we are approaching the stall...Have a talk with you instructor.

[cgzro]

If you wait for the Asi/Vsi or Alt to react its going to be quite developed.

Id go by feel, the sluggishness of the controls, the position of the column plus you will feel the drop long before the instuments show it. wing drop is a good cue too

[trey kule]

I dont want to get into an internet slap fest, but your VSI may not actually indicate anything but level flight as you approach a stall (same with the altimeter). As to the ASI, again, if the approach is gradual and insidious, there should not be much of a lag.. In any event if your speed is deteriorating below the target speed you are flying, you do not need to wait to initiate corrective action.

.

[Big Pistons Forever]

I with TK on this. You should be at most concentrating on recognizing when the aircraft is entering slow flight and recovering back to normal flight. You should never be anywhere near the stall when on instruments. If your instructor insists on doing stalls recover at the first indication which will usually be the stall warning horn. Pulling through the horn to the actual stall pitch down is IMO stupid.

[trey kule]

Id go by feel,

The recipe to get yourself killed flying on instruments.

[cgzro]

The recipe to get yourself killed flying on instruments.

So are you implying that the feel and position of the controls should not be taken into consideration in the determination of a stall when under instruments?

Why?

Note that I'm not arguing for the use of feel to fly on instruments (that would be stupid), I'm simply arguing for the use of feel and control postion to detect that you are in or near stalled before you see it on your instruments. Not sure why that is controversial? It was even brought up in the Air France investigation.

[trey kule]

A fair enough question for debate.

First, there is a difference between feel and position of the controls..the two should not be linked together.
I did not claim the position of any control (including engine and auxillary controls) should be ignored.
Secondly, there are many many physiological changes that occur where the body does not have outside reference and thinks the plane is in a different attitude than it is. The only way, and it is absolutely the only way on instruments, is to interpret the instruments and trust them. There is no feel involved. You make the plane do what the instruments tell you is necessary.
The pilot who flys by "feel" on instruments may feel the plane is turning when it is not. May feel it is not turning when it is.
May feel it is climbing when in fact, it is not (a problem even for non IFR durng night)departures. As to the controls getting sloppy, you are usually not holding them in a death grip, and if the trim is set, the only way you would know they are getting sloppy is to be moving them. Stalls, the kind you are trying to aviod during instrument flight do not occur deliberately, and you are not moving controls to get the feel of them.
The AF control issue, I thought was more about the fact that the right side and the left side controls were not connected, so one pilot could not feel what the other was doing. That is a bit of a tangent from feeling the controls as a method of detecting performance.
As an aside, a friend of mine with thousands upon thousands of hours in helicopters had a devil of a time trying to learn to fly them on instruments, as he kept trying to feel the sweet spot..It was just not there.
I am going to stick by my original claim...Learn how to interpret the instruments. Trust them. And base your performance on what they tell you, not on what you feel.

[cgzro]

First, there is a difference between feel and position of the controls..the two should not be linked together.

I disagree, for example heavy resistance to the elevator at significant deflection tells you something quite different than light resistance at that same deflection. Therefore the feel and position are related and together tell you something.

Secondly, there are many many physiological changes that occur where the body does not have outside reference and thinks the plane is in a different attitude than it is......

Don't want to debate that, its obviously true and I never said or implied otherwise.

[trey kule]

Well, we agree to disagree, but I think it might be more of an issue with semantics and interpretation than a real disagreement.

I have flown planes IFR who have controls so nicely balanced that you almost have to keep the airspeed indicator in focus all the time if it is a bit turbulent. Others have control forces that are heavy all the time. And again, you are not typically moving the controls very much unless you are really getting bounced around...
I have seen pilots , flying on autopilot with altitude select, reduce the power in a fast descent and then have the autopilot level out the plane while they are looking at one thing or another and the airspeed deteriorate almost to the stall.
I have seen pilots establish a climb, trim out the plane, and then get distracted while the airspeed quietly decays in the climb. There simply is no feeling the controls.
Lastly, stress removes the sensitivity. ATC calls and tells a pilot they have busted their altitude (read...CADORS coming up)...and the reaction to pull the nose up masks the feel.

The point I was trying to make , is feel is not the way to interpret unusual attitudes or decaying trends in the real world.(on instruments)..and that is supposedly what we are training for.
The original poster was talking about doing stalls on instruments as part of their night training.
My personal opinion is to find a new instructor who understands what is important to learn in instrument flying, and learn to avoid stalls on instruments. focus on the scan, and interpretaton and the recognitionof an unusual attitude and the correct recovery technique.

I want to be clear. The feel is there on some planes. But it will go unrecognized in a typcial real world situation on instruments. Fine for intentional slowing down or climbing VFR, or even on instruments, but , in my opinion, useless for the unitentional straying into unusual attitudes...And that is the objective , and recognizing those on instruments, and taking the necessary corrective action, I believe, is the important thing to learn.

In any event, I do instruct on instruments any more, so I will leave it to the more enlightened ones , and I will continue to have to deal with those pilots who have lots of "fun" time doing stallls on instruments
in training, but cant establsih a climb properly, or understand the relationshhip between power and attitude.

BTW... You would be surprised how many ex-IFR instructors have never actually flown in a cloud, and really lose it when they are required to do it the first few times .

[PanEuropean]

I'm working towards my night rating...

I admit I must have gotten rusty at performing stalls since completing my PPL, as I'm having some trouble detecting when the airplane is fully stalled...

Hi Arrow:

I think that the question you need to ask yourself is whether you want to be able to detect a stall once it begins to happen (and presumably then recover from it), or whether it would be more practical for you to develop observation skills that would prevent you from ever approaching a stall in the first place.

I have flown professionally for many years, and it is only on very rare occasions that I ever need to 'detect' a stall. I only need to stall the aircraft once, after major maintenance has been carried out, to confirm that the stall warning system works, or stall it twice (if it is a new aircraft and I am making the first flight), again, to confirm that the stall warning system works.

During all the rest of the time that I fly aircraft (typically to move them from one location to another), one of my major concerns is to ensure that I never let the aircraft get into such a low energy state that it might stall. In other words, I'm focused on totally avoiding any precursor to a stall (low speed, rapid change in angle of attack, turns with an angle of bank greater than 45 degrees, etc.).

If you are interested in polishing up your 'stall detection' skills purely for academic interest, then by all means go out with your instructor and spend an hour or so trying different types of stalls - not just the 'basic' stall with wings level and low airspeed, but climbing turn stalls, stalls resulting from a rapid increase in AOA, etc. Pretty soon you will be able to recognize not only the onset of the stall, but what actions lead to the stall itself.

Once you have satisfied your curiosity with that, I think it would be more practical for you to then ask yourself "How can I detect when the precursors to a stall begin to form, and how can I avoid ever getting into that situation?" The answer to that, I think, comes from not only monitoring your airspeed and attitude, but from knowing ahead of time exactly what combination of airspeed, attitude, and power you need to use for the various phases of flight. Once you know what airspeed, attitude, and power you need to use for all the different phases of flight, it will be very easy for you to recognize when "Something is not right here", and thus avoid ever getting close to a stall in the first place.

Unless, of course, one of your objectives for the flight is to function-test the stall warning system.

Michael

[trey kule]

Nice post Pan

As an aside, you only have to stall once after heavy maintainance? We are required to stall in all configuarations. (CAA) I have had a couple of interesting recoveries when flaps were not correctly rigged.
It was always done VFR, level flight and with a defined deacceleration.

Some good advice in your post.