Stall and Spin-Related Accidents

8/14/2019 Stall and Spin-Related Accidents

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Stall and Spin-Stall and Spin-RelatedRelated

AccidentsAccidentsGLIDING FEDERATION OF AUSTRALIAGLIDING FEDERATION OF AUSTRALIA


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LS3 - Parkes, 1990

Janus - Gympie 2005

Astir CS - Bendigo, 2004


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Stalling at Low AltitudesStalling at Low Altitudes

A stalling type of crash will be inevitable if:-A stalling type of crash will be inevitable if:- the glider is very low, andthe glider is very low, and

there is not a clear area immediately ahead and below.there is not a clear area immediately ahead and below.

Even if the pilot is fully aware of being close to the stall,Even if the pilot is fully aware of being close to the stall,he will instinctively hold off until the glider stalls down thehe will instinctively hold off until the glider stalls down thelast few feet rather than fly into obstructions at speed.last few feet rather than fly into obstructions at speed.

If the glider is being flown slowly in gusty conditions, theIf the glider is being flown slowly in gusty conditions, thestall may occur high enough for a wing to drop and for anstall may occur high enough for a wing to drop and for anincipient spin to develop with even more serious results.incipient spin to develop with even more serious results.


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These situations usually arise from runningThese situations usually arise from runningout of height on the circuit.out of height on the circuit.

They can also arise from arriving back far tooThey can also arise from arriving back far toohigh and by badly planned manoeuvring in anhigh and by badly planned manoeuvring in anattempt to correct that kind of position.attempt to correct that kind of position.

It is often found that the pilots concerned inIt is often found that the pilots concerned insuch accidents/incidents relied too heavily onsuch accidents/incidents relied too heavily onthe altimeter and did not receive adequatethe altimeter and did not receive adequate

training in circuit emergencies.training in circuit emergencies.


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How do we prepare our pilots to preventHow do we prepare our pilots to preventaccidents caused by stalling at low altitudes?accidents caused by stalling at low altitudes? By regularly running them out of height in theBy regularly running them out of height in the

circuit during training.circuit during training. By covering the students altimeter during circuitBy covering the students altimeter during circuit

training.training.

With regular practice, students learn toWith regular practice, students learn toamend their plans at an early stage, therebyamend their plans at an early stage, thereby

preventing the situation from developing andpreventing the situation from developing andleading to an accident.leading to an accident.


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UndershootsUndershoots

Most undershoot accidents occur because theMost undershoot accidents occur because the

pilot has not recognised that the glider ispilot has not recognised that the glider is

critically short of height until it is desperatelycritically short of height until it is desperately

low.low.

In very open country, the judgement ofIn very open country, the judgement of

heights, even down below 200 or 300 feet, isheights, even down below 200 or 300 feet, is

surprisingly difficult.surprisingly difficult.

Where there are trees or buildings nearby aWhere there are trees or buildings nearby adirect comparison can be made, and this is adirect comparison can be made, and this is a

good way of eliminating seriousgood way of eliminating serious

misjudgements.misjudgements.


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Most pilots do not instinctively look across andMost pilots do not instinctively look across and

compare their height with the trees unless theycompare their height with the trees unless they

have been taught to do so, and more oftenhave been taught to do so, and more often

than not a pilot will try to judge by angles andthan not a pilot will try to judge by angles and

positioning alone.positioning alone.

Often, the pilot does not even consider what heOften, the pilot does not even consider what he

will do if the glider hits some sink and loseswill do if the glider hits some sink and loses

some extra height.some extra height. Too much height often leads to situationsToo much height often leads to situations

where even full airbrake cannot prevent awhere even full airbrake cannot prevent a

drastic overshoot.drastic overshoot.


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When the glider is desperately low theWhen the glider is desperately low the

pilots handling often goes to pieces, andpilots handling often goes to pieces, and

he may over-rudder in an effort to gethe may over-rudder in an effort to get

round a final turn without touching a wing-round a final turn without touching a wing-tip or turning any steeper.tip or turning any steeper.

Over-ruddering causes extra drag and anOver-ruddering causes extra drag and an

extra loss of height or speed, and it oftenextra loss of height or speed, and it often

leads to stalling in the turn.leads to stalling in the turn.


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A Word on ThermallingA Word on Thermalling

Stalling is a real hazard duringStalling is a real hazard during

thermalling, where the glider is flyingthermalling, where the glider is flying

close to the stall.close to the stall.

Thermalling below the normal spinThermalling below the normal spin

recovery height can have fatalrecovery height can have fatal

consequences if the glider stalls andconsequences if the glider stalls and

the correct stall recovery action isthe correct stall recovery action isnot initiated promptly.not initiated promptly.


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Anticipation & RiskAnticipation & Risk

ManagementManagementThe solution to these problems isThe solution to these problems is

anticipation; that is, preventing them fromanticipation; that is, preventing them fromdeveloping by thinking ahead and takingdeveloping by thinking ahead and takingaction early.action early.

More stalling and spin training will not helpMore stalling and spin training will not helpto stop this type of accident.to stop this type of accident.

Manage risk by:-Manage risk by:-

Identifying and classifying a riskIdentifying and classifying a risk Avoiding the risk or risk situationsAvoiding the risk or risk situations Resolving or mitigating any effects orResolving or mitigating any effects or

consequencesconsequences..


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Managing the RisksManaging the Risks

He

igh

t

OPTI

ONSRememberOur options diminish as we get

closer to the ground!

Flightpath


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AnticipationAnticipation

Incidents can only be avoided if the pilot has a more openIncidents can only be avoided if the pilot has a more openmind about where he is going to land.mind about where he is going to land.

All too often the pilot has a plan in his mind and sticks to itAll too often the pilot has a plan in his mind and sticks to iteven when it should have become obvious that theeven when it should have become obvious that thesituation has changed and his plan is no longer feasible.situation has changed and his plan is no longer feasible.

It is sometimes quite hard for a person to do theIt is sometimes quite hard for a person to do theunconventional, but that may be the only safe option.unconventional, but that may be the only safe option.

If the pilot is thinking ahead, appropriate options couldIf the pilot is thinking ahead, appropriate options couldhave already been considered and he would have had thehave already been considered and he would have had theplan ready for use if more height was lost.plan ready for use if more height was lost.


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Stalling on the actual approach isStalling on the actual approach is

usually caused by failing to monitorusually caused by failing to monitor

the airspeed regularly or by failing tothe airspeed regularly or by failing to

react to its indications.react to its indications. Stalling can also be due to trying toStalling can also be due to trying to

stretch the glide instead of closing thestretch the glide instead of closing the

airbrakes, or stretching the glide afterairbrakes, or stretching the glide aftergetting into a desperate undershootgetting into a desperate undershoot

position.position.


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If a bad undershoot seems inevitable, promptIf a bad undershoot seems inevitable, promptaction is needed rather than waiting to see whataction is needed rather than waiting to see whathappens and how far you get.happens and how far you get.

If there is a possible area for a safe landing, useIf there is a possible area for a safe landing, use

the brakes and get down into it. Remember that itthe brakes and get down into it. Remember that itis far better to get down and then to run intois far better to get down and then to run intoobstruction than to stall onto it at flying speed.obstruction than to stall onto it at flying speed.

On a windy day with a strong wind gradient, youOn a windy day with a strong wind gradient, youare quite likely to lose some extra height andare quite likely to lose some extra height and

speed and low approaches are always very risky.speed and low approaches are always very risky.


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Unintentional Stalls atUnintentional Stalls at

HeightHeight It is obviously very important for theIt is obviously very important for the

pilot to learn to recognise all thepilot to learn to recognise all the

symptoms of the stall and to becomesymptoms of the stall and to become

familiar with them.familiar with them. If the symptoms are recognised,If the symptoms are recognised,

there is almost always plenty of timethere is almost always plenty of time

to prevent a stall occurring.to prevent a stall occurring.


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HeightHeight Many inexperienced pilots get so thoroughlyMany inexperienced pilots get so thoroughly

engrossed in the thermalling or what is going onengrossed in the thermalling or what is going onelsewhere that they are temporarily switchedelsewhere that they are temporarily switchedoff to how they are flying, e.g..:-off to how they are flying, e.g..:-

looking at the map and the ground for possible clueslooking at the map and the ground for possible cluesas to where they are,as to where they are,

looking for signs of possible lift to climb in, togetherlooking for signs of possible lift to climb in, togetherwith all the other little worries involved in a fieldwith all the other little worries involved in a fieldlanding.landing.

It is often at these times that the gliderIt is often at these times that the gliderbecomes stalled without the pilot noticing, andbecomes stalled without the pilot noticing, andthen his instincts are bound to be automatic asthen his instincts are bound to be automatic asthe nose and wing drops.the nose and wing drops.


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HeightHeight An accidental stall at height usually occurs becauseAn accidental stall at height usually occurs because

the pilot is not aware of the low speed, etc.the pilot is not aware of the low speed, etc.

Therefore all the training in the world will not preventTherefore all the training in the world will not preventthe pilot from responding instinctively because theythe pilot from responding instinctively because they

are not at that moment aware that the glider is stalledare not at that moment aware that the glider is stalled(Had the pilot been aware, he would have prevented(Had the pilot been aware, he would have preventedthe stall!).the stall!).

In this situation the pilot is bound to pull back andIn this situation the pilot is bound to pull back andapply the aileron and rudder to stop the nose and wingapply the aileron and rudder to stop the nose and wingfrom dropping. Of course the correct response is tofrom dropping. Of course the correct response is tomove forwards on the stick.move forwards on the stick.


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HeightHeight Accidental stalls seldom happenAccidental stalls seldom happen

when the glider is being flownwhen the glider is being flown

straight, and most result in one wingstraight, and most result in one wing

stalling before the other, causing astalling before the other, causing awing-drop.wing-drop.


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Incipient SpinsIncipient Spins

Any time that a wing begins to dropAny time that a wing begins to drop

at a stall it is the beginning of aat a stall it is the beginning of a

possible spin.possible spin.

The spin can only develop if the wingThe spin can only develop if the wing

is kept stalled and the glider isis kept stalled and the glider is

allowed to continue to yaw.allowed to continue to yaw.


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Recommended RecoveryRecommended Recovery

The recovery action recommended for any stall is toThe recovery action recommended for any stall is to

move forwards on the stick to unstall the wings bymove forwards on the stick to unstall the wings by

reducing the angle of attack.reducing the angle of attack.

A few seconds later the glider is unstalled and can beA few seconds later the glider is unstalled and can be

brought level and back to normal flight with the normalbrought level and back to normal flight with the normaluse of the controls.use of the controls.

This has the advantage that it does not require the pilotThis has the advantage that it does not require the pilot

to remember any special movement of the controls otherto remember any special movement of the controls other

than the movement forward to unstall.than the movement forward to unstall.


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Use of the RudderUse of the Rudder

Additional yawing caused by the excess use ofAdditional yawing caused by the excess use ofthe rudder in a turn will make the wing-dropthe rudder in a turn will make the wing-dropmuch sharper.much sharper.

At the instant of applying the excess rudder, itAt the instant of applying the excess rudder, it

speeds up the outer wing-tip, creating morespeeds up the outer wing-tip, creating morelift there, and gives the inner wing sweeplift there, and gives the inner wing sweepback in relation to the airflow, thus increasingback in relation to the airflow, thus increasingthe tendency to tip stall on that wing whilethe tendency to tip stall on that wing while

reducing it on the other.reducing it on the other. Yaw will also occur if the ailerons are used toYaw will also occur if the ailerons are used to

try to stop the dropping wing because of thetry to stop the dropping wing because of theextra aileron drag.extra aileron drag.


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Applying the opposite rudder will tendApplying the opposite rudder will tend

to reduce the yaw and so help evento reduce the yaw and so help even

out the stalling of the wings.out the stalling of the wings.

The rudder power of most gliders isThe rudder power of most gliders is

very poor and there may not be anyvery poor and there may not be any

visible effect when opposite rudder isvisible effect when opposite rudder is

applied in an incipient spin.applied in an incipient spin. It is not dangerous to apply theIt is not dangerous to apply the

opposite rudder in an incipient spin.opposite rudder in an incipient spin.


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Applying the opposite rudder cannot cause the spin toApplying the opposite rudder cannot cause the spin toreverse unless the pilot is keeping the stick right back.reverse unless the pilot is keeping the stick right back.

The only reason for an incipient or full spin changingThe only reason for an incipient or full spin changingdirection is if the stick is held right back so that thedirection is if the stick is held right back so that theglider is either kept stalled, or is re-stalled as theglider is either kept stalled, or is re-stalled as therotation stops.rotation stops.

If the incipient spin has progressed for more thanIf the incipient spin has progressed for more thanabout half a turn because the pilot has kept the stickabout half a turn because the pilot has kept the stickback, applying the full opposite rudder is a good thingback, applying the full opposite rudder is a good thingbecause it helps to stop the rotation and to even upbecause it helps to stop the rotation and to even upthe stalling of the wings.the stalling of the wings.


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The most effective way of dealingThe most effective way of dealing

with an incipient spin in practice is towith an incipient spin in practice is to

move forwards on the stick, apply themove forwards on the stick, apply the

opposite rudder to check the yaw andopposite rudder to check the yaw andthen to use all the controls normallythen to use all the controls normally

to bring the aircraft level.to bring the aircraft level.

New pilots are taught just to unstallNew pilots are taught just to unstallthe wings and then to get the wingsthe wings and then to get the wings

level using the normal coordination.level using the normal coordination.


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Unless the pilot is aware that the glider isUnless the pilot is aware that the glider is

stalled, he is bound to respond instinctively atstalled, he is bound to respond instinctively at

first, applying full aileron and rudder to try tofirst, applying full aileron and rudder to try to

stop the rapid wing-drop and pulling right backstop the rapid wing-drop and pulling right back

to try to stop the nose dropping.to try to stop the nose dropping.

If the pilot is aware that the glider is stalled,If the pilot is aware that the glider is stalled,

applying the opposite rudder at the same timeapplying the opposite rudder at the same time

as moving forwards on the stick should resultas moving forwards on the stick should resultin some reduction in the yawing movementin some reduction in the yawing movement

towards the dropping wing, and thereforetowards the dropping wing, and therefore

must be a good thing.must be a good thing.


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Unexpected StallsUnexpected Stalls

Most unintentional stalls occur, byMost unintentional stalls occur, by

definition, unexpectedly.definition, unexpectedly.

Usually the first obvious sign of what hasUsually the first obvious sign of what has

happened is that the pilot is banging thehappened is that the pilot is banging thestick on the rear stop with the nose stillstick on the rear stop with the nose still

dropping.dropping.

Provided that the stick is moved forward toProvided that the stick is moved forward to

unstall the wings the possibility of a fullunstall the wings the possibility of a full

spin will have been avoided.spin will have been avoided.


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Most types of glider are reluctant toMost types of glider are reluctant to

enter a full spin unless they are beingenter a full spin unless they are being

flown with the c.g. on or very close toflown with the c.g. on or very close to

the aft limit, that is by light pilots.the aft limit, that is by light pilots. Whether it is a full spin or just anWhether it is a full spin or just an

incipient one is academic if the gliderincipient one is academic if the glider

stalls a few hundred feet up.stalls a few hundred feet up.


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To recover from a steep dive, ease is theTo recover from a steep dive, ease is theoperative word.operative word.

If the glider is trimmed for a normal cruisingIf the glider is trimmed for a normal cruisingspeed, because of the longitudinal stability itspeed, because of the longitudinal stability it

will require a forward movement and pressurewill require a forward movement and pressureon the stick to keep it diving at a higheron the stick to keep it diving at a higherspeed.speed.

This means that in most cases it is more likelyThis means that in most cases it is more likely

to be a matter of relaxing the forward pressureto be a matter of relaxing the forward pressureto allow the aircraft to level out rather thanto allow the aircraft to level out rather thanpulling it out with a positive backwardpulling it out with a positive backwardpressure on the stick.pressure on the stick.


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The Stick PositionThe Stick Position

The position of the stick in steady flight is aThe position of the stick in steady flight is a

very clear indication of the angle of attack.very clear indication of the angle of attack.

Having the stick back near the rearmostHaving the stick back near the rearmost

stop should warn the pilot that he is closestop should warn the pilot that he is closeto the stalling angle for the wing.to the stalling angle for the wing.

If the nose is dropping in spite of pullingIf the nose is dropping in spite of pulling

back and hitting the back stop, this is aback and hitting the back stop, this is a

clear indication that the glider is stalled,clear indication that the glider is stalled,

and a forward movement is needed for aand a forward movement is needed for a

few seconds to let the wing unstall.few seconds to let the wing unstall.


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In most unintentional stalls, the stick position on theIn most unintentional stalls, the stick position on the

back stop will be the first symptom to beback stop will be the first symptom to be

recognised.recognised.

Very often the noise of the airflow will haveVery often the noise of the airflow will have

increased because of the yawing movement.increased because of the yawing movement. Most of the other symptoms will either be absent orMost of the other symptoms will either be absent or

will go unnoticed in the moments of panic.will go unnoticed in the moments of panic.

The fact that the glider is not responding normallyThe fact that the glider is not responding normally

must cause alarm to any pilot until the cause ismust cause alarm to any pilot until the cause isidentified.identified.


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If the glider is stalled and enters a spin atIf the glider is stalled and enters a spin atheight, the inability to recover will be due aheight, the inability to recover will be due alack of spin recovery training.lack of spin recovery training.

With insufficient experience, the pilot is likelyWith insufficient experience, the pilot is likely

to be slow to recognise the spin and slow toto be slow to recognise the spin and slow toreact.react. Because the stall occurs unexpectedly it mayBecause the stall occurs unexpectedly it may

well cause a temporary panic.well cause a temporary panic. While we do have gliders that spin, it is vitalWhile we do have gliders that spin, it is vital

to give pilots enough experience to recogniseto give pilots enough experience to recognisewhat is happening and to make the rightwhat is happening and to make the rightmoves instead of panicking and doingmoves instead of panicking and doingnothing.nothing.


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The Effects of Rain onThe Effects of Rain on

the Stallthe Stall On most high performance machines, aOn most high performance machines, a

spread of splattered flies on the leadingspread of splattered flies on the leading

edges can account for up to a quarter ofedges can account for up to a quarter of

the gliders performance.the gliders performance. Water on the wings increases the stallWater on the wings increases the stall

speed.speed.

Some gliders have a definite change inSome gliders have a definite change in

both stall speed and characteristics.both stall speed and characteristics.


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More About SpinMore About Spin

RecoveryRecovery The standard method of recovery must beThe standard method of recovery must be

followed because it has been proven to befollowed because it has been proven to beeffective during testing.effective during testing.

It involves applying full opposite rudder andIt involves applying full opposite rudder and

then, with the ailerons central, moving thethen, with the ailerons central, moving thestick steadily or progressively forwards untilstick steadily or progressively forwards untilthe spin stops.the spin stops.

Finally, the pilot centralises the rudder andFinally, the pilot centralises the rudder andeases out of the dive.eases out of the dive.

To reduce the risk of over-speeding withTo reduce the risk of over-speeding withmodern machines, the airbrakes can bemodern machines, the airbrakes can beopened fully at any time during the spin oropened fully at any time during the spin orthe recovery.the recovery.


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More About SpinMore About Spin

RecoveryRecovery All gliders and light aircraft have to recoverAll gliders and light aircraft have to recover

satisfactorily with the standard method.satisfactorily with the standard method.

In the standard recovery, the full opposite rudder isIn the standard recovery, the full opposite rudder is

always applied first, and if it does slow down thealways applied first, and if it does slow down the

rotation, the nose of the glider will automaticallyrotation, the nose of the glider will automaticallydrop, helping to unstall the wings.drop, helping to unstall the wings.

In this way the rudder is a very powerful influenceIn this way the rudder is a very powerful influence

on the spin recovery because it helps the pitchingon the spin recovery because it helps the pitching

movement and also slows the rotation.movement and also slows the rotation.


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BlanketingBlanketing

Before the days of T-tails, there was aBefore the days of T-tails, there was a

possibility of the downward movement of thepossibility of the downward movement of the

elevator causing some blanketing of the rudderelevator causing some blanketing of the rudder

and reducing its effectiveness.and reducing its effectiveness.

This is another reason for standardising theThis is another reason for standardising the

rudder movement first, but it is not relevant torudder movement first, but it is not relevant to

gliders with T-tails where no rudder blanketinggliders with T-tails where no rudder blanketing

can occur.can occur.


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Modes of SpinningModes of Spinning

It is possible for an aircraft to haveIt is possible for an aircraft to have

several different modes of spinning,several different modes of spinning,

and all of them may not have beenand all of them may not have been

discovered during the testing.discovered during the testing. Using the ailerons during the recovery,Using the ailerons during the recovery,

for example, may be the means offor example, may be the means of

entering one of these other modes ofentering one of these other modes ofspin.spin.


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Spin Test FlyingSpin Test Flying

Little spinning is carried out during the test flying of a newLittle spinning is carried out during the test flying of a newtype of glider.type of glider.

Entries are made with every different kind of control input:Entries are made with every different kind of control input:full in-spin aileron, full out-spin aileron, airbrakes in andfull in-spin aileron, full out-spin aileron, airbrakes in andout, c.g. forward and c.g. aft, etc., using the standardout, c.g. forward and c.g. aft, etc., using the standard

method of recovery to stop the spin.method of recovery to stop the spin. To check the recovery from the stabilised spin, the glider isTo check the recovery from the stabilised spin, the glider is

held in the spin for a full five turns if that is possible.held in the spin for a full five turns if that is possible. The authorities do not require other methods of recoveryThe authorities do not require other methods of recovery

to be tested, and it is therefore not always possible to beto be tested, and it is therefore not always possible to be

sure whether using the aileron, for instance, will flatten thesure whether using the aileron, for instance, will flatten thespin and make it more difficult to stop.spin and make it more difficult to stop.


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The Position of the C.G.The Position of the C.G.

With any type of aircraft the characteristics of aWith any type of aircraft the characteristics of a

spin vary according to the loading, so that the spinspin vary according to the loading, so that the spin

becomes flatter as the c.g. is moved back.becomes flatter as the c.g. is moved back.

This will also affect how far the stick has to beThis will also affect how far the stick has to be

moved forwards to effect a recovery.moved forwards to effect a recovery. It is therefore important to always think of the stickIt is therefore important to always think of the stick

movement as being a progressive forwardmovement as being a progressive forward

movement made until the spin stops.movement made until the spin stops.


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The Effect of the RudderThe Effect of the Rudder

In many gliders the spin may stop as soon as theIn many gliders the spin may stop as soon as thefull opposite rudder is applied.full opposite rudder is applied.

In others the stick will have to move quite a longIn others the stick will have to move quite a longway forwards before the wing unstalls and the spinway forwards before the wing unstalls and the spin

stops.stops. Where this is the case, the full opposite rudderWhere this is the case, the full opposite rudder

may not even appear to change the spin, and themay not even appear to change the spin, and thespin will continue until the movement forward isspin will continue until the movement forward issufficient.sufficient.

Because each spin may be slightly different, it isBecause each spin may be slightly different, it isimportant to always make a progressive, steadyimportant to always make a progressive, steadymovement forwards of the stick until the spinmovement forwards of the stick until the spinstops.stops.


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Control LoadsControl Loads

In most gliders the rudder will have overbalanced andIn most gliders the rudder will have overbalanced andmoved hard over in the direction of the spin.moved hard over in the direction of the spin.

If you are in doubt about the direction of the spin, pushIf you are in doubt about the direction of the spin, pushagainst the overbalancing load and reverse the rudder.against the overbalancing load and reverse the rudder.

The airflow over the ailerons often tends to move theThe airflow over the ailerons often tends to move the

stick towards the direction of the spin and they shouldstick towards the direction of the spin and they shouldbe centralised for the recovery.be centralised for the recovery. The elevator may overbalance so that the force neededThe elevator may overbalance so that the force needed

to move forwards on the stick is abnormally high. Doto move forwards on the stick is abnormally high. Donot mistake stick pressures for stick movement. Thenot mistake stick pressures for stick movement. Thestick must be moved forwards to make the recovery.stick must be moved forwards to make the recovery.


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Training ProblemsTraining Problems

In many training gliders it is difficult toIn many training gliders it is difficult todemonstrate spinning and the spin maydemonstrate spinning and the spin maystop when the full opposite rudder isstop when the full opposite rudder isapplied.applied.

If this happens, it is important to move theIf this happens, it is important to move thestick forwards sufficiently to ensure thatstick forwards sufficiently to ensure thatthe glider does not re-stall.the glider does not re-stall.

When a glider recovers so easily, a rapidWhen a glider recovers so easily, a rapidmovement forward on the stick oftenmovement forward on the stick oftenresults in a very steep recovery and a highresults in a very steep recovery and a highspeed dive.speed dive.


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Training ProblemsTraining Problems

If the spin stops when the full oppositeIf the spin stops when the full opposite

rudder is applied, the stickrudder is applied, the stick mustmustbe movedbe moved

forwards to allow normal flight.forwards to allow normal flight.

Failure to do this will result in the reversalFailure to do this will result in the reversalof the spin from one direction to another.of the spin from one direction to another.

If an aircraft is very difficult to get into aIf an aircraft is very difficult to get into a

spin, it also may be very difficult to recover.spin, it also may be very difficult to recover.

It is not unknown for so-called unspinnableIt is not unknown for so-called unspinnableaircraft to come to grief by getting into aaircraft to come to grief by getting into a

stable spin.stable spin.


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Light Stick ForcesLight Stick Forces

It is very important to watch for anyIt is very important to watch for any

tendency to use a jerky forwardtendency to use a jerky forward

movement on the stick during the fullmovement on the stick during the full

recovery.recovery.This is often a sign of nervousnessThis is often a sign of nervousness

and usually means that more spinand usually means that more spin

training is needed.training is needed.


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Avoid Abrupt MovementsAvoid Abrupt Movements

Movements of the stick must be aMovements of the stick must be a

controlled, progressive movement rathercontrolled, progressive movement rather

than a rapid, uncontrolled push or jerk.than a rapid, uncontrolled push or jerk.

Pilots should ease the glider out of thePilots should ease the glider out of thedive rather than pull it out.dive rather than pull it out.

There have been several cases of two-There have been several cases of two-

seaters being overstressed by pilots pullingseaters being overstressed by pilots pulling

back hard to recover from steep dives afterback hard to recover from steep dives afterspin recoveries.spin recoveries.


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ConclusionConclusion

Most of the serious stall/spin accidents areMost of the serious stall/spin accidents arecaused by poor planning which leads tocaused by poor planning which leads tosituations involving:-situations involving:- difficult manoeuvring near the ground; anddifficult manoeuvring near the ground; and

putting the pilots under stress so that they makeputting the pilots under stress so that they makemistakes or fly badly enough to stall and spin in.mistakes or fly badly enough to stall and spin in.

Careful instruction and constant practice isCareful instruction and constant practice isneeded if the stall and spin accidents are toneeded if the stall and spin accidents are to

be prevented altogether.be prevented altogether. It is important to be able to recognise all theIt is important to be able to recognise all the

symptoms of the approach of a stall in ordersymptoms of the approach of a stall in orderto be able to prevent it.to be able to prevent it.


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To prevent or to stop a spin theTo prevent or to stop a spin the

wings must be unstalled by means ofwings must be unstalled by means of

a forward movement of the stick.a forward movement of the stick.

Unstalling the wings takes away theUnstalling the wings takes away the

cause of the autorotation and thencause of the autorotation and then

the wings can be brought level usingthe wings can be brought level using

the stick and rudder normally.the stick and rudder normally.


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In most cases with either incipient or fullIn most cases with either incipient or fullspins, any movement forward, or evenspins, any movement forward, or evenjust relaxing the backward movement ofjust relaxing the backward movement ofthe stick, would prevent or stop the spinthe stick, would prevent or stop the spinimmediately.immediately.

Regardless of the attitude of the glider, ifRegardless of the attitude of the glider, ifit is not responding to moving back onit is not responding to moving back on

the stick or if the stick is hitting the backthe stick or if the stick is hitting the backstop, a forward movement must be madestop, a forward movement must be madeto allow the glider to unstall.to allow the glider to unstall.


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A presentationA presentation

bybyChristopher ThorpeChristopher Thorpe

Chief Flying InstructorChief Flying Instructor

Beaufort Gliding ClubBeaufort Gliding Club

Stall and Spin-Related Accidents

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Transcript of Stall and Spin-Related Accidents