Stalling
 

Flight Training News Pg 13 discusses an accident involving a student and his instructor whereby he was teaching stall recovery and unfortunately didn't recover from a spin.

The AAIB have made a safety recommendation that 'oscillatory stalling' is not included in any flight exercises during flight training.

Oscillatory stalling is described as 'holding the aircraft in the stall using maintained back pressure on the control column when leads to a nodding motion or 'oscillating' pitching movement. With appropriate rudder inputs to control any wing drop this could lead to a spin.

My question is this:

Flight exercises on stalling include entries, symptoms and characteristics of being stalled. In a PA28, the nose nod or 'oscillatory pitching movement' is a symptom of the stall.

In order for students to experience how this feels and therefore be able to recover, I also allow students to enter a stall and hold a stall with maintained back pressure before they recover, keeping the aircraft in balance with light inputs to the rudder and alierons kept neutral. Flight Training News also appear to have spoken to a number of instructors where this practise is regarded as common place.

Are the AAIB saying that holding an aircraft in a deep stall for students to experience its effects and subsequent recovery should be stopped as it is not safe practise due to being close to the ingredients of a spin ?

At what stage approaching the stall do you therefore allow a student to recover ? Incipient or actually stalled ?

I would be interested in other instructors thoughts !!

TurboJ

The recommendation was about holding it in a stall

If you enter a fully developed stall and recover after experiencing the sensations of a fully stalled aircraft then fine:)

The recommendation was to avoid holding the stick back and maintaining the stall (which I know a lot of instructors do as a routine thing).

Probably more likely to inadvertantly spin if practicing the latter:{

What is the purpose of this manoeuvre? Anyone?

None whatever! If you use rudder for anything other than maintaining balance during a stall, you are inviting a spin. 'Stopping wing drop' or, even worse, 'picking up a wing with rudder' is an archaic nonsense which should have been stamped on years ago.

Also, never let a student hold the a/c in the stall unless you are doing so to demonstrate light pre-stall buffet management if your a/c type has such a characteristic.

The student is learning to recognise and recover from the stall with minimum height loss. You show him (with him following through) the identification of the fully developed stall - buffet, nose drop, wing drop, high RoD, nodding dog or whatever, then tell him that any one of those is an indication of a fully developed stall and he should recover when he recognises any of those stall identifications.

I don't use 'signs' and 'symptoms' ever since medical stuents commented that this was bolleaux. So now it's stall warnings (keep going and I'm going to stall, idiot!) and stall identifications (I warned you, you didn't listen and now I bloody well HAVE stalled like wot I told you I was going to!).

BEagle

Succinctly put. I was hoping that someone would quickly pounce on the "pick up the wing with rudder" old wives' tale.

Have to confess to some disappointment at the alacrity of your response, though. I expected the "rudder" proponents to jump to its defence. I s'pose that thread is done and dusted now.

The problem seems to be they didn't recover from the spin!
Was it a Slingsby by any chance?

so Aerlion is better to lift the downgoing wing ?

Recover not maintain stall
 

The point here is teach the students to recover from the stall but NOT to teach him to sustain it - you want to limit height loss

(Full Aileron control will be possible when the recovery is effected)

Correct (assuming that you mean aileron)- but only when the wings are unstalled.

hmm, assuming every stall occurs in a benign and balanced state (i.e little or no yaw or +/- gz), then the aileron would suffice.

what about unbalanced, a turn, any significant yaw, either wing going south, (obviously so) , in that case using aileron will only accelerate the "south" going wing, whether erect or inverted an to be honest, you really have to begin using your feet at that stage. (i.e step on the ball) which is not really "using rudder to pick up the wing" , all you are doing is kicking her around, removing the yaw, so a modicum of stick fwd/bwd as the case may be moves you away from the stall-departure zone

Not sure personally about the deep (mush) stall in a pa-series, but it would certainly give a student confidence, if they wish to be cpl's then surely they want to explore all the facets of an aircraft characteristics ? (from a safe height I may add)

Anyone 'kicking her around' at low speed should themselves receive a sound kicking!

Standard Stall Recovery:

FULL POWER and Control Column centrally forward until Stall Identification ceases.

Then (and only then) level the wings.

Then recover from the descent.

DO NOT USE RUDDER FOR ANY OTHER PURPOSE THAN TO MAINTAIN BALANCE!

Beagle

I was criticised on a check flight with an FIC for the order in which I explained standard stall recovery.

I was told it should be control column forward to reduce the angle of attack of the wings and then apply full power.

Reason ? The effect of applying full power causes the nose to raise which increases the angle of attack, thereby prolonging the stall !!

Therefore standard stall recovery:

Relax the back pressure to reduce the angle of attack of the wings.
Apply full power.
Maintain aircraft in balance by controlling yaw with rudder.
Once speed increases past Vx, select a climbing attitude.
Check carb heat to off, unless selected off as airspeed was reducing.

To quote a legendary CFI, instructing is all about terminology ! I realise its being pedantic......however that was the critique of a recent check flight

TJ

some of us don't fly straight and level all the time.

oh, and adding full power as you mention, would in some aircraft (because of the low speed and associated torque) roll you on your back.

what then ?

Slow Flight
 

Zgcbc...............

Anyway going back to the original issue it seems a good idea to
keep things simple.

We are teaching a student to fly.

We KIS - Keep it simple.

Hence Ex 10A Slow flight
Ex 10B Stalling

This is stall prevention
and stall recovery .... and thats what this thread is all about

Keep it simple and there will be no problems OK :}

'Standard Stall Recovery'

1 Stick centrally forward to unstall the wing
2 Full power to reduce height loss
3 Prevent/reduce wing drop if it occurs with opposite rudder
4 When all signs of the stall have ceased nose to the horizon then climb away if necessary when speed increases

1. Centrally forward to reduce chance of wing drop possibly leading to a spin but PRIMARILY TO REDUCE THE ANGLE OF ATTACK which is why you are stalling in the first place

2 Full power to reduce height loss. - student not convinced? show them a stall and don't use power to recover - amazing! the aircraft still recovers just loses more hight

3 Use the secondary effect of rudder to prevent the wing dropping further as trying to use aileron will only increase the angle o attack further and lead to further wing drop etc

4 Nose to horizon when stall has ceased

Often hear instructors talk about "teaching stalling" when we should be teaching NOT to stall.

Have also heard an instructor brief a stude that the first thing you should do if you get a wing drop is apply "full opposite rudder" :uhoh: Turns out one of the schools round here really does teach thier instructor trainees this! They also send their studes to "practice stalling" solo :uhoh:

The main thing is to reduce angle of attack, I tell them not to apply power until you have at least 60 knots (PA38, PA28) hopefully by this ex they should be able to recognise the "feel" of the airspeed without having to look at the ASI. Applying power too early will induce yaw and could lead to a wing drop. Secondary importance of power is shown by the fact that gliders can recover from stalls, too!

apologies for intrusion.......:uhoh:

TurboJ, I respectfully contend that the FIC instructor was an utter ar$e! If you do not control the a/c attitude and balance when applying full power, then stall recovery may well be delayed. Delaying application of full power will certainly increase the height loss during recovery.

Charlie Foxtrot India - maybe it's some of your ex-students to whom we've had to re-teach stall recovery. Why wait until 60KIAS? Teach them to maintain balance and to control the attitude correctly when applying full power!

And that old wives' tale of full power at low speed causing a/c to roll onto their backs is a myth with certificated aircraft.

It's clear from the thread that opinion varies quite widely. Since we can't all be correct in our methodology, it must be the case that lots of students are being badly taught.

I've heard it said that, in general in the UK, stall-spin awareness is an area in which FIs do let down their students. I've certainly met chaps (not FIs) who believe that they can recover from a stall solely with the application of power.........and others who engage in "now-legendary" frantic rudder-paddling in an attempt to prevent any wing drop. In my experience, very few PPLs are comfortable with flight at the lower speeds......so landings are bound to be a bit of a trial, aren't they?

I know that at my school, the 2 hours stall-spin awareness is often severely curtailed and the exercises are skimped in order to rush into the circuit. Appropriate adjustments are then made to the student' records in order to fulfil the criteria for licence issue.

I'd be surprised if my experiences are unusual.

The wider issue is, I think, one of standards. There does prevail, in some schools, a propensity to teach down to a price, rather than up to a standard. This is facilitated by the system of examination for the PPL' syllabus. Far better, in my opinion, to adopt a system more akin to CAAFU.....where the examiner has no commercial interest in the student's outcome.

If an independent examiner regularly found that X's students were complete duffers at low-speed work, there would be an opportunity to address X's deficiencies, I suppose.

Anyone else seen fragrant abuses by "school" examiners? Or perhaps I shouldn't ask.

did I really say "fragrant abuses"?

Bogbeagle

Absolutely bang on (fragrance aside).

Which 2 hours is that?

To the best of my knowledge, there is no requirement for any minimum amount of stall-spin awareness, and there hasn't been since the introduction of JAR. There are a number of different stalling scenarios to be covered, the aim being for the student to understand the symptoms of the approaching stall and the fully developed stall, and to be able to recover with minimum height loss. Once a student can perform these excercises satisfactorilly (and by that I mean that the student has demonstrated sufficient knowledge of the stall and the recovery of the stall to be able to carry out the exercises), move on to circuits. For some students, this will take less than an hour. For others it will take several hours.

FFF
---------------

This thread re-opens the argument (from a previous thread) for the need for some sort of instructor standardization body.

Question is why do we teach stall recognition and recovery.
When is an aircraft going to stall.
Probably not at 4000 feet on a bright sunny day.

When an aircraft stalls and the wing drops eg C152/PA38 the first thing a pilot does is apply opposite aileron, worsening the situation. And is unlikely to be power off.
It is an instinctive reaction to aircraft roll.
We all know it probably takes an hour of stall practise to teach the student not to use aileron, which quickly gets forgotten.

And i would imagine that any instructor on a windy day climb out experiencing severe wing drop would probably also use aileron to recover combined with rudder.

exactly right, you should stall the aircraft in as many possible legal flight configurations as you can manage, climbing full power, climbing turning full power , descending flaps, tighten up turns and so forth.

This malarky about straight ahead summers day stalling is leading students up the primrose path.

by the way Beagle, I have rolled a Cessna 152 years ago in a high AOA, slow speed , with flap and fullpower , and I can tell rudder had absolutely no effect round she went and we were along for the ride.......

and I pickup the downgoing wing all the time when I do aeros, and I do it with tap tap rudder, and whatever stick is rwq'd

The flowers you will probably need will not be primroses......

Another consideration which I don't think anyone has highlighted relates to the certification requirements .. ie what is demonstrated and investigated during the OEM development and regulatory certification process.

This has varied over the years. One should have an idea of what the particular aircraft was subject to ... if one goes outside this .. then one might get an unpleasant surprise at some stage.

For instance, one popular light twin was certificated on the basis of only approaching to the indications of stall .. a very experienced test pilot instructor related the tale of one of his students who persevered with holding an example of the Type/Model into the stall ... and promptly ended up in an inverted spin.

What the OEM writes up in the handling notes, POH, etc., is worth giving due weight .....

FFF

Quite right. Another misapprehension bites the dust, courtesy of JAR FCL 1.125, appendix 1.

So, no minimum requirement for stall-spin awareness training......or instrument awareness.

"misapprehension". My dear Mrs Malaprop, surely you mean misconception

I agree with you that a recovery with power reduces the altitude loss but if we teach students to apply full power when the stick is still forward the situation may become dangerous. A friend of mine died with a C152 because they stalled and applying full power the aircraft spinned.
For this reason I want that my students learn to:
1) reduce AOA and only after that
2) apply full power
Usually in the first recovery the student will lose a lot of altitude. But after 3 or 4 recoveries he/she take confidence with the sequence, full power is really close to nose down, and the altitude loss will decrease.

Ciao!!!

Rosanna

I second Rosanna's post. It's especially true of less stable aircraft like PA38, any aerobatic planes, etc. - applying full power early in the stall/spin tends to cause a flat spin.

I find this thread very illuminating. People are talking about picking up wings with rudder and 112hp engines causing the aircraft to rotate around it's longitudinal axis with the controls having no effect and/or causing 'flat spins'. This all makes me believe that they have been taught incorrectly and are teaching incorrectly.

I'm talking about the CAA /JAR syllabus here and not the FAA or CASA one, which I have little experience of but I believe they are similar. I always thought that stalling exercise was a prevention exercise and to get the best out of it, recognition has to be taught first. Then recovery with minimum height loss in various configurations and attitudes. The key to this is with 'minimum height loss' and you can only achieve this with the application of power. This is how I was taught to teach the exercise and how I always did it myself.

1: Recognition - take some time on this, if the student can't recognize the warnings of the approaching stall or the stall itself there is no point in continuing.

2: Recovery - this can be achieved with reducing the angle of attack. You should elicit from the student the height loss, then point out the loss with use of power. (The last aircraft I was teaching on, the PA 28 typically lost 300' in a recovery without power, 100' with.)

This should take a minimum of a whole hour long lesson if it's going to be done properly with the average student. Then:

3: Recognition and recovery in other configurations/ attitudes (with flap, power, gear, air brakes, asymmetric, any attitude - even upside down if you like!) The key to this is the recovery with min height loss with the emphasis of saving you skin on the approach to landing stall. To achieve this effectively, you have to build up a scenario with a high workload and distractions. this should take more than one lesson.

The stall recovery is simplicity itself in it's execution (although you wouldn't believe it reading this thread!). You move the control column centrally forward until the buffet stops, simultaneously applying full power. You use the rudder TO PREVENT FURTHER YAW - and this only! When the wings are unstalled (i.e there is no buffet - and this is another reason you have to have to have the recognition squared away), you select a level attitude with aileron and elevator.
Some points on what has been said here.

Use of rudder: tramping the rudder around other than to prevent yaw is asking for trouble. The primary recognition points of an incipient spin are buffet with undemand yaw. If you demand some yaw intentionally by using more rudder than is required to prevent any yaw from the action of the stall or applying power, you are inviting the aircraft to spin.

Use of aileron: By increasing the angle of attack by lowering an aileron, you are inducing the wing to stall deeper. In my experience the only aircraft where aileron use with buffet was appropriate was a swept wing jet where the aerodynamics are very different.

Use of power: To reduce the height loss, you need power. The last aircraft I instructed on professionally stalled at about 80 knots and has a 1200hp engine. There was no problem controlling it at the point of stall with full power. The only aircraft to my knowledge which had a problem with this was the Bolton Paul Baliol with a 1600hp merlin engine. It was taken out of RAF service partly for this reason. If an aircraft cannot be controlled in this fashion it would not be certified. (This may not apply to some multi-engine types asymmetric if they are at or below their Vmca).

The only slightly dodgy stall characteristic I have ever experienced was the Tucano which rolls to about 120 degrees angle of bank at the stall in a final approach configuration stall in a left turn. Still, by following the recognized recovery technique, it is still possible to recover in about 400' safely. To get to this stage though, you have to ignore the warnings of the high nose attitude, the less effective controls, the low and decreasing airspeed, the audio warner, the stick shaker, the angle of attack gauge, the approach angle of attack indicator - and the buffet! This re-enforces the emphasis on recognition.


Roll on instructor standardization!

I can't add anything to this post, except to offer thanks to Dan.

Dan's post has put my mind at rest that my training in recognising the 'incipient stall' in various configs and the recovery procedures wasn't at all incorrect afterall.

I was a bit concerned to read posts that suggested the rudder be applied for anything other than to prevent further yaw on applying power.

Dan

Thanks for your post. I am very pleased to be 'singing from the same hymn sheet.'

However, I come back to my original point.

In a PA28,the stall itself includes an oscillatory pitching effect which the AAIB says is not included in ab initio flight training and should not be practised by UK flying instructors. However, students are required to be able to recover from a fully developed stall which includes this pitching effect.

Would it be right to say that as soon as this 'nodding effect' is reached, the student recovers or the fully developed stall should not be developed to include this oscillatory effect.

Regards......TJ

Coming from a gliding instructing background, I can only concur the stall/spin recognition/avoidance/recovery is at least inconstantly, if not badly, taught.

BGA instructors are rigorously coached in stall spin recovery in all kinds of configurations and loadings at heights down to below 1000ft (some demo only).

There is a particularly nice one which involves stalling/spin entry in under and over ruddered turns and works really nicely in a C152. All my PPL students get to see it and have a go.

From my perspective the ‘spin avoidance only’ teaching is a bit of a cop out –possibly engendered by a lack of suitable available aircraft.

PF

From my experience, the oscillatory pitching effect of the PA28 at the stall is a result of the control column being held and maintained fully back and is a product of the high level of pitch stability enjoyed by that aircraft. If you get to that stage with a student, he/she is flying the aircraft to the limit of its angle of attack capabilities and is in a full deep stall. Remember that the aim of stall training is to recognise the stall at it's onset and recover with the minimum height loss. If you ever take the student to this stage, it should be once and for demonstration purposes only. The aim of this exercise is to recognise the warnings of an approaching stall and avoid them in the future. there should few reasons for the student to take a PA28 to the 'nodding' stage.

I'm glad that someone has bought up the subject of glider stall training. I first trained as a glider instructor and IMHO, glider stall training is superior to powered. Glider pilots are more likely to fly a wider range of types than power pilots and at speeds much closer to the stall. My experience comes from the Bocian (stall below 500' and it's goodbye) through the tailess Fauvel 28 (hoik the stick back and you can flick loop) to the Dart 17 with no washout (stall and you're guarenteed an incipient spin). Some gliders have truly horrible stall characteristics, but most are benign.

I have to admit that what I have for Tomahawk is pure hearsay. On the other hand, a 360 hp engine on a Yak-52 (almost twice as heavy as PA38) is known to affect the stalling/spinning behaviour, and the flight manual explicitly prescribes to pull the throttle to idle while recovering from a spin / incipient spin.

The Yak has a large heavy prop which will acts as a gryroscope. You don't want gyroscopice forces affecting the recovery. I think it has more to do with this rather than the airframe being spun around by the prop. In the Tucano, the incipient spin recovery was centralize the control column and close the throttle - for this reason. In the less powerful Chipmunk and Bulldog, it was just centralise the contol column.

Dan, I totally agree with this one, gyroscopic forces probably have more to do with it. They would also make a bigger contribution to the asymmetry of the situation (left vs. right spin).

While we are on the subject of stall recovery. Just the other day during an
IR(ME) 170A, I carried out the standard stall recovery, ie Stick neutral/forward, Power Wings level etc. I was then corrected by the FI, to recover the Twin engine aircraft from the stall by basically powering out of the stall, no lowering of the nose to reduce AoA. As an FI myself this strongly goes against all of my principles and what I teach my PPL's. Thinking about this further after my 170A (which was signed off incidently), the implications of loss of power in one engine during a stall recovery carried out by power alone could be quite... well dangerous. Any views on ME stall recovery would be appriciated.

thanks
mint

When a stall catches a student unawares we have hopefully instilled in the student an automatic reaction .....stick forwards and apply full power (simultaneously)

It is difficult to instill an instinctive reaction which has got many variables depending on circumstances hence why we have to boil it down to "pitch and power":) .