Exercise 10 – Stalling
1. ENTRY, FULL STALL AND STANDARD STALL RECOVERY (SSR)
- Not violent or unpleasant Control easily regained
- HASELL check
- Clearance turns
- Close throttle/prevent yaw
- Maintain straight and level
- No trimming below 70 kts
3. SIGNS OF APPROACHING STALL
- Low and decreasing airspeed
- Decreasing control effectiveness
- High nose attitude
- Audio stall warning
- Call out “approaching stall”
- Light Buffet
- Call out “stall”
4. SYMPTOMS OF FULL STALL
- Heavy buffet
- Aircraft descends (sink)
- Possible nose drop (nodding)
- Possible wing drop
5. POWER-OFF RECOVERY
- Yoke centrally forward (ailerons neutral)
- Immediately symptoms (warner, buffet) cease – maintain attitude
- Level the wings, if necessary
- At 60 kts, apply full power, ease into climb
- Note height loss (according to POH section 5)
(Stress: No need to rush, make smooth, progressive control inputs)
6. RECOVERY WITH A POWER (STANDARD STALL RECOVERY – SSR)
- Yoke centrally forward
- Simultaneously apply full power
- (counteract yaw and pitch up effects)
- Once the wings are unstalled, maintain pitch
- attitude and level the wings if necessary
- Ease into a climb
- Note (reduced) height loss
7. WING DROP
- Initially, teach only if it happens naturally. Later, induce if necessary
- Carry out SSR
- Oppose any induced yaw with GENTLE use of rudder until wings unstalled
8. INCIPIENT STALL RECOVERY
- At FIRST sign of the stall – carry out SSR
- Smaller pitch change to unstall wings
- Note minimal height loss
9. STALLS WITH POWER AND FLAP
- Lower stall speeds
10. STALL UNDER APPROACH CONDITIONS
- From simulated circuit
- Nominate “simulated ground level” (SGL)
- HASELL check on simulated downwind (SGL +1000 ft)
- 90° turn for LOOKOUT
- “Base leg” (1500 RPM, Flap 20)
- Descending turn (20° AOB initially, then increase to 30°), after 90°, raise nose progressively At first sign of stall: SSR (rolling wings level once unstalled) Ease into climb, at safe height and speed (SGL +200 ft and 65 kts) raise flaps
- Wings level on simulated final – select full flap
- Stabilize at 60 kts, note pitch attitude
- Raise nose progressively
- At first sign of stall Standard stall recovery, retract flap to 20, and by stages.
- Resume back to normal condition
11. STALL IN TURNS AND AT HIGHER SPEEDS
- 40° banked level turn, note HIGHER STALL SPEED
- Dangers of “snatch pull”, secondary stall
12. SLOW FLIGHT
- At VS + 5 kts, clean and flap 20, ( if maneuver is clear, it can be introduced with flap 30)
- High nose attitude – lookout more difficult
- Higher power required ( approximately 1800 RPM as initial reference)
- Speed unstable
- Very limited manoeuvre margin, small angles of bank for heading changes (10 degree bank. A green triangle on bank indicator will be reduced by low speed)
STALLING: AMPLIFYING NOTES
- This exercise is an essential part of teaching your student to handle the aeroplane confidently and competently throughout the full flight envelope – in this case, the low speed regime. To do this you must be confident of your own skills in handling the aeroplane in full stalls and in all your briefings and flight instruction must strike the correct balance between teaching both the dangers of stalling inadvertently and incorrect recovery techniques and the fact that practicing stalling properly is both safe and necessary. Consequently, frequent dual and solo practice in recoveries from all types of stall goes on throughout the course.
- The exercise has 2 distinct aspects:
1. Recognition of the signs of an approaching stall – for stall avoidance.
2. Recognition of symptoms of a fully-developed stall and the actions required – to recover from a stall. (The ultimate aim of this part of the exercise is for your student to learn how to recover with minimum height loss. This is inherent in the correct stall recovery drill.) Before each stall, brief your student explicitly on whether he is to recover on your instruction – “Recover Now”, or on his own initiative – at the first signs of the stall. In either case, teach him to say “Recovering”.
3. You must ensure that your student learns the correct technique at each stage before proceeding to the next one. Teach clean, power-off stalls, demonstrate stalls with flap and power and in turns and finally, teach the practical applications of stall avoidance in the approach and landing configurations.
- Ensure your student understands:
1. Lift, the stalling angle of attack and the stalling speed
2. Characteristics of the stall
3. Factors affecting the stalling speed
4. Attitude and the stall
5. Recovery from the stall – use of power
THREAT AND ERROR MANAGEMENT
- Ensure your student understands the reasons for each item in the HASELL check and always carries them out conscientiously. In particular, he must make clearing turns before each stall. Teach how to make these turns to position the aircraft as necessary.
- Your student may be a little nervous at first but he will gain confidence as he becomes able to identify and recover from the stall. Nervousness may lead to air sickness; watch for symptoms and discontinue the exercise if necessary.
- Ideally, you should demonstrate a full stall and recovery at the end of the lesson preceding the first stalling exercise, so that the student sees that it is not in any way a frightening experience and allays any fears about danger or violent sensations. Do not try to teach during this first demonstration – just point out the point of stall and the commencement of recovery. During the subsequent post-flight discussion, answer any questions your student may have so that he is better prepared for the detailed lesson on stalling.
SIGNS OF AN APPROACHING STALL
- HASELL Checks Height: Sufficient to recover by 1500 ft agl
- Airframe: Configuration as required
- Security: Hatches and harnesses secure. Loose objects stowed
- Engine: Mixture rich. T’s & P’s normal
- Location: Clear of active airfields, built up areas, clouds, controlled airspace and danger areas
- Lookout: Clearing turns L/R
- Power – Idle (Carb Heat, A/R); Balance
- Maintain Level (No trimming below 70 kts)
Low & Decreasing IAS
High Nose Attitude (Not always a sign of an approaching stall, but an unnaturally high nose-up attitude should “start warning bells ringing”.)
Decreased Control Effectiveness
Stall Warner and/or Light Buffet (felt through the yoke) – Stress that these two are the only unequivocal signs of an approaching stall but that stall warners can fail, so your student must always be aware of all the other signs and symptoms.
(For your initial demonstration, it may be advantageous to allow the aeroplane to descend slightly in order to slow down the rate of speed decay and give enough time to point out all the signs.)
Give your student plenty of practice at entering the approaching the stall and detecting the signs for himself.
- Stall warner plus heavy buffet (felt throughout the airframe)
- High ROD
- POSSIBLY (but not always) – Nose drop; wing drop
Ensure your student develops the confidence to maintain a full stall until you tell him to recover. Yoke fully aft, maintain ailerons neutral. (At this stage, do not allow a wing drop to develop, control it yourself with rudder, if necessary, emphasizing that your student must keep the ailerons neutral.)
- Power-off recovery
First learning the power-off recovery eases your student’s workload, as he does not have to contend with the pitch and yaw effects of applying (full) power. He can concentrate on using the elevators to pitch down just enough to unstall the wings (stall warner and buffet cease) AND NO MORE. This skill is fundamental to achieving the aim of recovering with minimum height loss because, no matter how good the rest of his technique, lowering the nose too much will always cause avoidable height loss. Consequently, no matter how long it takes, make sure your student has mastered this technique before moving on.
- Yoke centrally forward (ailerons neutral) to pitch down
- Immediately symptoms (warner, buffet) cease – maintain that pitch attitude; level the wings, if necessary
- At 60 kts or above, apply full power; ease into a climb
- Note height loss
- (Stress: No need to rush, make smooth, progressive control inputs) Recovery with power
- Elevators are used as before (but remind the student also to counter the pitch-up effect of applying power)
- Full power is applied simultaneously, maintaining balance
- Once the wings are unstalled, level the wings, if necessary
- Ease into a climb
- Note (reduced) height loss
- This is the core of Standard Stall Recovery (SSR).
- Recovery when a wing drop
Before practising stalling solo, your student must be able to recover safely if a wing drops, but, unless a wing drop occurs naturally in the first stalling exercise, delay teaching this aspect until he has more experience. Teach that using aileron will not always raise a dropped wing and may aggravate the situation under certain circumstances. In some aeroplanes used by Flying Academy, a wing drop is rarely severe; in this case, ignore it and carry out the Standard Stall Recovery which unstalls the wings quickly, so that aileron can then be used to level the wings. If the wing drop is acute, teach GENTLE use of rudder to oppose the induced yaw (NOT TO “PICK UP THE WING”) at the same time as carrying out SSR. If wing drop never occurs naturally, you will have to induce it by entering stalls deliberately out of balance, in order to teach your student the correct recovery technique. Emphasize the first action to recover any stall condition/symptom must be forward movement of the yoke.
- Recovery from an incipient stall
Any unintentional stall should always be stopped at the incipient stage. This prevents high sink rates developing and avoids any possibility of wing drop.
- At the FIRST sign of a stall (buffet or stall warner) – Take SSR (Note: the pitch change to unstall wings is small).
Note much reduced height loss, if any.
2.Give your student ample practice in recovering, ON HIS OWN INITIATIVE, at the incipient stage.
- Stalls with flap and power
Demonstrate, not teach, the effects of flap (20°) and power (1700 RPM) on the stall (lower stalling speeds, greater chance of wing drop) and that standard stall recovery is always effective. If a wing drop occurs, use the opportunity to teach corrective action.
- Stall under approach conditions
We need to practise the approach stall, to let the student get familitisation with traffic circuit procedure, set approach configuration stalls from a simulated circuit. Remember: each maneuver has a reason for practice. Teach stall recoveries in the base-to-final turn and on simulated final.
For both stalls, teach:
- Nominate an altitude as simulated “ground level”.
- At “ground level” + 1000 ft carry out HASELL check.
- Turn (level) through 90° for LOOKOUT onto simulated Base Leg.
- Establish descent (1500 RPM, Flap 20).
- At “ground level” + 700 ft, turn (descending) through 90° (20° AOB initially, then increase to 30°) for LOOKOUT.
- (Note the normal descending attitude)
- After 90°, raise the nose progressively.
- At first sign of stall: SSR (rolling wings level once unstalled).
- Once climbing at safe height and speed (200 ft “agl” and 60 kts or above) raise flaps.
- Set-up as above.
- Wings level on simulated final – select full flap.
- Stabilise at 65 kts, trim – note pitch attitude.
- Raise nose progressively.
- At first sign of stall: Standard stall recovery , flap to 20 – safe height/speed retract remainder.
For both stalls, stress the very unusual attitudes, high control forces to approach the stall and very low IAS, any one of which (let alone all 3) should alert any pilot to an approaching stall long before the stall warner or buffet occur. Emphasize that good awareness of all available cues is the best possible defence against trouble. Point out also that, using correct techniques, recovery is made safely above the simulated ground level.
Stall at higher speeds and in turns
Ensure your student understands the aircraft can be stalled at any speed and power. Although you cannot demonstrate the more extreme cases because of the possibility of overstressing the aircraft, show that in a (power-off) turn at about 40° bank angle, the stall speed is higher than with wings level (because of the increased Load Factor).
Emphasize two practical implications of this:
- First, overbanking in the base-to-final turn will increase the stall speed and make an inadvertent stall more likely.
- Second, “snatch pulling” during a stall recovery is likely to lead to a secondary stall and greater height loss overall – hence the need to EASE out of the descent during recovery.
- Emphasis is being laid increasingly on low speed handling and appreciation of situations which can lead to spins or incipient spins.
Flight at within 10% of Stalling Speed both clean and with full flap.
- High nose attitude – lookout more difficult
- Higher power required
- Speed unstable (wrong side of drag curve)
- Very limited maneuver margin, small angles of bank for heading changes.
The most common fault is that students lower the nose too far during stall recovery. This is often because of nervousness and a desire to “get away from the stall” as quickly as possible. The two best counters to this are:
- Building confidence by having the student maintain the stall for at least 10 to 15 seconds in the early stages to learn for themselves that (at a safe altitude) the full stall is not inherently dangerous.
- Ensuring that your student has learned to lower the nose NO MORE THAN NECESSARY during power-off recoveries.
Note: If your student has serious problems mastering this, reduce his workload and stress levels by flying the aeroplane yourself, and getting him to follow through and call “STOP” as soon as the stall warner and buffet cease.
He may need a lot of practice but do not move on to the rest of the lesson until this essential technique has been mastered.
- If your student has difficulty keeping the aircraft straight during the approach to the stall, remind them to look well ahead at a reference feature and that rudder will be required as IAS reduces to maintain balance.
- If your student applies power hesitantly or slowly, emphasize that the amount of height lost and the speed at which control is regained both depend on the prompt use of full power. If, on the other hand, your student tends “slam” the throttle – remind him of the reasons for smooth handling.
- Poor coordination of rudder with the application of power is also quite common; as well as practice, the best cure for this is confidence. This will allow your student to carry out all actions calmly and methodically (no panic) and apply basic techniques properly.
- If a wing drops at the stall, your student may tend to correct by instinctive use of aileron. Stress the need to keep the ailerons neutral. Practice and experience are necessary for the student to learn the proper method.