Coordinated turning stall and spins
Chris OCallaghan
November 9, 2003
Turning Stalls and Insipient Spins
As promised, apropos to this discussion on spin entry from coordinated
turning stalls, I took a tow this morning to 5000 feet agl and
performed a series of coordinated and cross control turning stalls.
The aircraft used was a Ventus 2bx, delivered this year. I have
approximately 75 hours in this aircraft and about 525 hours total in
the model. I flew the glider at approximately 70% of the aft cg limit.
Wing loading was 7.8 lbs per square foot. All stalls were entered in
the first positive flap position.
My intention was as follows: to perform a series of turning stalls,
both coordinated and cross controlled, to determine the departure and
post departure characteristics of a modern fiberglass sailplane.
Stalls were entered gently and in a shallow bank (lower wingtip on
horizon). Whether coordinated or cross controlled, I fixed the
controls in the pre-departure position for three full seconds after
departure (that is, no attempt was made to recover immediately after
the stall break).
Once off tow I completed two clearing turns, then stalled the glider
wings level twice to establish attitude. I then entered a coordinated
shallow left turn and gently eased back on the stick. The stall broke
cleanly. The glider initially yawed about 30 degrees to the left,
dropped its nose through the horizon, then began to increase its bank
angle and gain speed. G forces accumulated and I recovered from the
spiral dive at about 80 knots and roughly 70 degrees of bank. (As
noted above, the elevator was held firmly aft and aileron and rudder
neutral until recovery was initiated.
I repeated the same maneuver to the right. The stall break was less
clean (more mushy). Development of the ensuing spiral dive was slower,
but airspeed and bank angle both accumulated until I released the
controls and initiated a recovery.
I repeated this sequence with like results.
I then entered a shallow bank turning stall (left) while skidding
slightly. As the low wing began to drop, I applied about ½ stick
travel to the right, ostensibly to raise the dropping wing. Entry into
the spin was immediate and dramatic. The glider yawed approximately
ninety degrees while dropping it nose to about 60 degrees below the
horizon. I left the controls in this position for a count of three
(one one thousand, two one thousand…) The glider completed
approximately 1.25 rotations before I initiated a recovery (stick
forward, ailerons neutral, opposite rudder, pull up from dive).
I repeated this process to the right. However, this time, I gently
accelerated the stall (achieving a slightly higher nose attitude
before departure). Once again, I skidded the turn (10 to 20 degrees),
and tried to pick up the low wing as it stalled, this time with full
deflection of the aileron. The ensuing spin entry was even more
dramatic. I was unable to measure rotation rate (even roughly) because
the glider's nose went immediately past vertical. As I lost the
horizon I became disoriented, until I looked out at the wingtip and
found the horizon again. I nonetheless fixed the controls for a count
of three. There was no noticeable g build up until I initiated a spin
recovery. Max speed during the dive was just above 120 knots, about 20
knots more than I typically see for a recovery from a fully developed
spin.
It should be noted that my glider has a flap redline of 80 knots. In
all cases, if airspeed exceeded 80 knots, I moved the flap handle to
the first negative position.
My interpretation: while the glider exhibited a yawing motion during
the coordinated turning stall, it did not auto rotate, nor did it show
any such propensity. Some pilots may find the dropping wing, yaw
motion, and reduced g force of a coordinated turning stall
disquieting, but when compared in sequence to an actual autorotation
leading to a fully developed spin, the prior is patently docile.
Height loss after an immediate recovery from a coordinated turning
stall using a release of back pressure and coordinated ailerons and
rudder could be measured in 10s of feet. The spin, however, from entry
to the bottom of the dive recovery was measured in hundreds. Loss of
height for the first spin, from entry, through development, to the
bottom of the recovery dive was 475 feet. The second: 750 feet.
Conclusions: draw your own.
Andy Blackburn
Thanks for the great info.
9B
Don Johnstone
Did the glider start to recover from the spin with
positive flap selected? My understanding is that in
a flapped glider the first action is to zero the flaps.
Do you think that by selecting a negative flap setting
this accelerated the glider to a greater velocity than
selecting zero flap would have done? (I do not know
offhand the limiting speed for a Ventus in zero flap)
You quote figures of 475ft and 750ft for the fully
developed spiins. Do you have any figures for the spiral
dives off the co-ordinated turns? (I do note that you
delayed recovery for 3 seconds) It seems to me that
any stall in the final turn will result in hitting
the ground before recovery can be completed which bears
out what I have always said, teaching people to recognise
the approach of a stall and/or spin, and take appropriate
preventive action, is more important than teaching
spin recovery.
One final question, if a spin is entered at 300 feet
should recovery even be attempted? Are the chances
of survival greater if the glider hits the ground spinning
than if it is part recovered and 'tent pegged'? Interesting
what?
At 00:00 12 November 2003, Chris Ocallaghan wrote:
Andy Durbin
> Posted this to the discussion on spinning Blaniks from a coordinated turning stall.
>
> November 9, 2003
> Turning Stalls and Insipient Spins
>I then entered a shallow bank turning stall (left) while skidding
> slightly. As the low wing began to drop, I applied about ½ stick
> travel to the right, ostensibly to raise the dropping wing. Entry into
> the spin was immediate and dramatic. The glider yawed approximately
> ninety degrees while dropping it nose to about 60 degrees below the
> horizon. I left the controls in this position for a count of three
> (one one thousand, two one thousand?) The glider completed
> approximately 1.25 rotations before I initiated a recovery (stick
> forward, ailerons neutral, opposite rudder, pull up from dive).
Chris,
Thanks for taking the time to post this report.
It seems that the test aircraft is very unforgiving of poor recovery
technique. Is this typical of modern 15m ships? How would it have
behaved in the same situation with a full ballast load?
When I transitioned from the ASW-19 to the ASW-28 I explored its
characteristics in turning stalls at the aft cg limit and found, just
like the 19, it was benign even with abused control inputs.
Andy (GY)
Michael Stringfellow
after a fatal accident there last year. The findings were that the ship was
generally very stable, but could snap into a spin if not properly
controlled - sometimes going inverted. Recovery heights were alarmingly
large. The fatal accident occurred off tow from under 1,000 feeet, as I
recall.
Mike
ASW 20 WA
"Chris OCallaghan" <fiveni...@yahoo.com> wrote in message
news:236582a0.03111...@posting.google.com...
> (one one thousand, two one thousand.) The glider completed
Chris OCallaghan
Don Johnstone <REMOVE_TO...@bittering.gioserve.com> wrote in message news:<bot38m$1gsfe2$1...@ID-49798.news.uni-berlin.de>...
> Excellent post, I do have a couple of questions.
> Did the glider start to recover from the spin with
> positive flap selected? My understanding is that in
> a flapped glider the first action is to zero the flaps.
> Do you think that by selecting a negative flap setting
> this accelerated the glider to a greater velocity than
> selecting zero flap would have done? (I do not know
> offhand the limiting speed for a Ventus in zero flap)
Correct, I should have added that as part of spin recovery I moved the
flap to the first negative position. Though this is not expressly
dictated in the flight manual, the ensuing dive will certainly exceed
the flap redline (including 0 degrees). And, of course, dumping the
flap will immediately decrease AOA.
>
> You quote figures of 475ft and 750ft for the fully
> developed spiins. Do you have any figures for the spiral
> dives off the co-ordinated turns? (I do note that you
> delayed recovery for 3 seconds) It seems to me that
> any stall in the final turn will result in hitting
> the ground before recovery can be completed which bears
> out what I have always said, teaching people to recognise
> the approach of a stall and/or spin, and take appropriate
> preventive action, is more important than teaching
> spin recovery.
>
Approximately 200 to 250 feet, including the 3 second delay prior to
recovery. Unfortunately, my trace from the flight is not particularly
instructive. My FR was set at 4s intervals, so it doesn't show much
detail. Height loss is interpolated from the pressure altitude trace
as rendered in SeeYou.
> One final question, if a spin is entered at 300 feet
> should recovery even be attempted? Are the chances
> of survival greater if the glider hits the ground spinning
> than if it is part recovered and 'tent pegged'? Interesting
> what?
>
That's a tough one to answer. I see your point: better to hit the
ground at 70 knots than 100 knots. In either case I suspect the
results will be the same. I suppose it a matter of whether you expire
at the scene or several hours later in an ICU. To that end, I'd always
try to recover -- your chances of survival going from miniscule to
maybe.
> >(one one thousand, two one thousand?) The glider completed
Don Johnstone
final question is not so much speed as deceleration.
I once saw a tiger moth hit the ground spinning, both
pilots survived albeit one is now a paraplegic. It
is not just forward speed but a matter of what strikes
the ground first, a matter of pure chance I agree.
What is certain is that in a dive the most likely thing
to reach the scene of the accident first is the nose
of the glider where the soft part sits. This may indeed
happen in a spin but forward speed is not the main
factor, it is the rate of descent and will this be
less in a spin than in a dived and accelerating condition?
It's not speed that kills you it's stopping. I really
don't know and I am not eager to find out either :-)
Whatever the answer the best solution is to avoid the
spin in the first place but sadly it is not a perfect
world.
The only difference between a fatal and non-fatal accident
is the dead body and that can also be a matter of pure
blind chance.
At 17:06 12 November 2003, Chris Ocallaghan wrote:
Snip
>> One final question, if a spin is entered at 300 feet
>> should recovery even be attempted? Are the chances
>> of survival greater if the glider hits the ground
>>spinning
>> than if it is part recovered and 'tent pegged'? Interesting
>> what?
>>
>
>That's a tough one to answer. I see your point: better
>to hit the
>ground at 70 knots than 100 knots. In either case I
>suspect the
>results will be the same. I suppose it a matter of
>whether you expire
>at the scene or several hours later in an ICU. To that
>end, I'd always
>try to recover -- your chances of survival going from
>miniscule to
>maybe.
>
>
>>
>> At 00:00 12 November 2003, Chris Ocallaghan wrote:
>> >(one one thousand, two one thousand?) The glider completed
Duane Eisenbeiss
"Don Johnstone" <REMOVE_TO...@bittering.gioserve.com> wrote in
message news:bot38m$1gsfe2$1...@ID-49798.news.uni-berlin.de...
>
> should recovery even be attempted? Are the chances
> of survival greater if the glider hits the ground spinning
> than if it is part recovered and 'tent pegged'? Interesting
> what?
>
> >
In the early 1960s I rebuilt a Pratt-Read glider. This glider was used by
the USA Navy during early WW 2 (1941-42?) for flight training. During the
rebuild I obtained an original Navy Flight Manual for the glider. In the
manual, in bold print, was a sentence that stated " If entering a spin below
1000 feet DO NOT attempt recovery."
The reason for this was that the Pratt-Read tended to spin flat. Recovery
from a spin was near vertical for several hundred feet at a speed of more
than 100 mph. Vertical speed in the flat spin was something like 500
ft/min. Therefore it was deemed safer to hit the ground in a flat spin
rather that nose down in a vertical dive.
I would think that most (all??) modern gliders will not spin flat.
Therefore, whether one allows the spin to continue or attempts recovery, the
attitude of the glider will be nose down. With a recovery attempt there is
at least a chance of survival.
Duane
Chris OCallaghan
I underestand completely your concerns. It's a subject that's troubled
me for a long time, and I seem prone to flip flopping. The problem
isn't so much a question of energy... you'll have less in the spin
than in the ensuing dive after recovery (both of which are nose down),
but having a "procedure" that you can apply without thinking. When
close to the ground, you simply don't have time to observe and react
to more than a few inputs. For example, if I were to cross-control the
aircraft into a stall below 300 feet, if I were over trees, I might
just lock up the controls, close my eyes, and get ready for the hurt.
But to do this I would have to overcome my rote training... that is,
if I sense a departure, I recover immediately. I'm not sure that type
of switch would be valuable. The lesson I've taken away from this
discussion is that in the pattern, the yaw string stays bolt straight.
An unexpected stall can be handled if the aircraft is coordinated. If
not, the bottom falls out quickly.
If you accept as axiomatic that a stall can happen at any speed and at
any attitude, then I have to place priority on coordination fist,
airspeed second, though both are clearly primary concerns in the
pattern.
It is a virtue, or perhaps a nuissance, of our sport, that when near
the ground, the envelope narrows significantly. Between 1000 agl and
10 agl is like climbing solo. Falling is not an option, and we need to
attune ourselves to that.
Chris OCallaghan
> Chris,
>
> Thanks for taking the time to post this report.
>
> It seems that the test aircraft is very unforgiving of poor recovery
> technique. Is this typical of modern 15m ships?
Of those I've flown, yes and no. Most are very resistant to stalling
if the yaw string is straight back. They will mush rathar than
departing. However, they are all intolerant of improper recovery. Note
that in my coordinated turning stalls I initiated no recovery. I
simply let the glider seeks its own path. By keeping the ailerons and
rudder neutral, I was letting the tail do its job -- that is,
providing stability. (It was my original contention that if you didn't
stick an aileron into the airstream, the stalled wing couldn't produce
enough drag to overpower the tail.)
I have always entered spins through a misapplication of the controls.
Various models differ in the amount of misuse they'll tolerate. For
example, a Lark IS-28 will spin if you stick your hand out the clear
view in a left turning stall (only a slight exageration). The Grob 103
has only a very small spin entry window -- to the point that most
pilots don't have the patience to find it and thus pronounce it
unspinnable. And yet, once in the spin, the 103 is perhaps the most
interesting. (The SGS 1-26E is, in my opinion, the ultimate spin
training platform. Easy entry (big ailerons), easy recovery (just let
go), and a very stable spinning motion that lets you get used to
attitude and rotation rate. Only disadvantage is that you'll be
teaching yourself. Start high.)
How would it have
> behaved in the same situation with a full ballast load?
So long as the CG remains the same, yes, I think so. But recovery
would, in all cases, require more altitude. Frankly, I don't do much
experimenting with water on board. I am too heavy to fly at or below
gross with full tanks, and I don't like the idea of flinging 2/3 of a
tank of water out to the tip during a spin. That assymetry would only
add to the altitude I'd eat up during recovery.
>
> When I transitioned from the ASW-19 to the ASW-28 I explored its
> characteristics in turning stalls at the aft cg limit and found, just
> like the 19, it was benign even with abused control inputs.
The 19 is a pussycat. And though I haven't flown the 28 yet, I bet
it's even sweeter.
>
> Andy (GY)
Bill Daniels
> I have always entered spins through a misapplication of the controls.
> Various models differ in the amount of misuse they'll tolerate. For
> example, a Lark IS-28 will spin if you stick your hand out the clear
> view in a left turning stall (only a slight exageration).
I must mildly object to this general characterization of the Lark, although
it's possible that they vary considerably from one IS28 to another. I have
never flown one that behaves as you describe.
The IS28B2 that I just sold (SN 102) behaved more or less as you described
the behavior of the Ventus 2bx. As such, I think of the Lark as a wonderful
advanced trainer for pilots making the transition to glass. My time in the
Lark made my first Nimbus flights very comfortable.
Bill Daniels
Robert Ehrlich
> ...
> I have always entered spins through a misapplication of the controls.
> Various models differ in the amount of misuse they'll tolerate. For
> example, a Lark IS-28 will spin if you stick your hand out the clear
> view in a left turning stall (only a slight exageration). The Grob 103
> has only a very small spin entry window -- to the point that most
> pilots don't have the patience to find it and thus pronounce it
> unspinnable. And yet, once in the spin, the 103 is perhaps the most
> interesting. (The SGS 1-26E is, in my opinion, the ultimate spin
> training platform. Easy entry (big ailerons), easy recovery (just let
> go), and a very stable spinning motion that lets you get used to
> attitude and rotation rate. Only disadvantage is that you'll be
> teaching yourself. Start high.)
During my recent instructor course (last September) I had some spin
training in a PW6 (no other glider allowed to spin was available).
I found it very easy to enter as well as to recover the spin. After
that the (meta) instructor said "I guess that even if you release
all controls, it will recover", so we tried it and it recovered, then
I said "But we had the trim set for flight at max L/D, I guess that
with full aft trim it does not self recover", we tried it and it
did not self recover.
Don Johnstone
the glider departed at 300ft I would be straight into
recovery as well. I suppose the point I am trying to
make is that departure from flight with insufficient
distance between the glider and the ground is going
to hurt whatever we do. We spend an awful lot of time
teaching spin recovery, and rightly so. We seem to
me, to spend less time emphasising the signs and symtons
of approaching stalls/spins and this I feel needs to
be put right. The cpncentration on keeping balanced
flight when near the ground indicates that the problem
has been thought about and recognised. How many glider
pilots have thought that deeply and really understand
that lighting fast recovery techniques will not help
when close to the ground? How many are able to recognise
the onset of disaster and take recovery action before
it happens? The people who have been posting on this
thread almost certainly have but what of the silent
ones?
The final turn stall/spin claims many every year. Are
we really approaching the problem in the right way?
As an aside it is not just glider pilots who get it
wrong. I recall reading an accident report of an airliner
which had taken off from Heathrow back in the 60's
or 70's. The aircraft stalled at about 3000ft and hit
the ground in a stalled condition. There were 3 qualified
ATPL pilots in the cockpit, two of them qualified as
captain on type. None of them it would appear recognised
that the airplane was stalled.
What chance have we mere mortals got if the gods get
it wrong?
Robert Ehrlich
I completely agree on the point that training should more
focus on early detection and correction of incipient stall/spin
than on recovery of fully developed ones. As my previous favorite
sport was windsurfing, I developed a feeling for recognizing this
situation, because in this case, if you don't react immediately,
you can't avoid falling in water on the upwind side. I had a discussion
with a German pilot who did the same and feels the same thing.
Anyway, each time before I turn to final, I recite in my mind: "Watch your
speed and symmetry, here is the place where people kill themselves",
and I think I am going to say the same thing to my students.
W.J. (Bill) Dean (U.K.).
correct reflexes that the stall is prevented, or recovery is made with
minimum loss of height. But it is less likely to go wrong if there is also
good understanding.
There are three dangers from a stall/spin:
1. You hit something before recovery to normal flight.
2. You overstress the glider before recovery to normal flight.
3. After recovery you are not able to make a normal landing, because of
the height you have lost, or the direction you are now pointing.
It is essential to judge all these circumstances to know when a stall/spin
must not be risked.
There are four stages of an inadvertent stall/spin.
1. Avoid altogether.
2. Recognise that a stall/spin is close.
3. Recognise that the glider has stalled / is starting to spin.
4. Recover.
Too many people think that to avoid a stall/spin altogether what you need is
to be expert and quick at recognising that you are nearly stalled. The
real problem is that the glider can depart into a steep stall/spin without
any prior warning so far as the pilot is concerned; this is not because the
pilot failed to notice symptoms that the stall was close, but because there
weren't any. This is more likely to happen to a type known to readily spin
(Puchacz, IS28) but it can happen to any type (K21, Discus).
What matters is the angle of attack:
a. Angle of attack higher than the critical angle, you are stalled and
likely to have lateral instability (spin entry).
b. Angle of attack at the critical angle, you are stalling.
c. Angle of attack below the critical angle but close, you are at risk
from stalling in any gust wind gradient or shear, or due to inaccurate
flying.
If speed is low you are more likely to stall other things being equal, but
it is possible to stall at high speed, and possible to be at a very low
speed and not be stalled; what is critical is the angle of attack and not
the speed.
Inaccurate flying of itself will only stall you if you are already at a high
angle of attack, nearly stalled; the inaccuracy may tip you into the stall,
and the actual departure may be more violent and more complete. At a low
angle of attack whatever you do with ailerons and rudder will not stall you
(but it may cause a lot of extra drag, which may lead to a higher angle of
attack).
Inaccurate flying makes it more difficult to hold the desired angle of
attack, and to know if the angle of attack is increasing because it
disguises symptoms of high angle of attack. It will also increase drag
perhaps when you do not want any unnecessary loss of energy.
To avoid stalling keep the angle of attack well below the stalling angle.
How?
If you want to increase the angle of attack, you move the stick back (and
the elevator up).
If you want to reduce the angle of attack, you move the stick forward (and
the elevator down), this is why the recovery from a stall or from nearly
stalled always includes moving the stick forward.
If you are moving the stick back you are calling for a higher angle of
attack, whatever you reason for moving it back.
If you are moving the stick forward you are calling for a lower angle of
attack, again whatever your reason for moving it forward.
Therefore to be sure of avoiding an inadvertent stall/spin, part of our
flying must include monitoring stick movement and position. This is more
important than monitoring speed and change of speed (which is also
essential).
W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.
>
> "Don Johnstone" <REMOVE_TO...@bittering.gioserve.com> wrote in
> message > news:bp0neh$1j6s5h$1...@ID-49798.news.uni-berlin.de...
>
> <snip>
>
> We spend an awful lot of time teaching spin recovery, and rightly so. We
> seem to me, to spend less time emphasising the signs and symptoms of
> approaching stalls/spins and this I feel needs to be put right. The
> concentration on keeping balanced flight when near the ground indicates
> that the problem has been thought about and recognised. How many glider
> pilots have thought that deeply and really understand that lighting fast
> recovery techniques will not help when close to the ground? How many are
> able to recognise the onset of disaster and take recovery action before it
> happens? The people who have been posting on this thread almost
> certainly have but what of the silent ones?
>
> The final turn stall/spin claims many every year. Are we really
> approaching the problem in the right way?
>
> <snip>
>
Mike Lindsay
>we really approaching the problem in the right way?
>As an aside it is not just glider pilots who get it
>wrong. I recall reading an accident report of an airliner
>which had taken off from Heathrow back in the 60's
>or 70's. The aircraft stalled at about 3000ft and hit
>the ground in a stalled condition. There were 3 qualified
>ATPL pilots in the cockpit, two of them qualified as
>captain on type. None of them it would appear recognised
>that the airplane was stalled.
>What chance have we mere mortals got if the gods get
>it wrong?
>
>
But if you are referring to the accident I think you are, didn't the
enquiry find that the two younger pilots were terrified of saying
anything to the very senior captain, who was probably having a heart
attack at the time?
At least we don't get that in gliders, thank goodness.
--
Mike Lindsay
W.J. (Bill) Dean (U.K.).
accident (Trident 1 G-ARPI near Staines on 18th June 1972), it is now
available on-line.
BGA Website, Info for Clubs & Members, Safety, Links -
http://www.gliding.co.uk/bgainfo/safety/links.htm .
Air Accidents Investigation branch (AAIB) - http://www.aaib.gov.uk/ ,
Formal reports, Full reports, a.. No:4/73 - Trident I, G-ARPI, near Staines
http://www.dft.gov.uk/stellent/groups/dft_control/documents/contentservertemplate/dft_index.hcst?n=5250&l=4 .
W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.
>
> "Mike Lindsay" <mi...@sailplane.demon.co.uk> wrote in message
> news:Tey7obAoXpt$Ew...@sailplane.demon.co.uk...
> Mike Lindsay
>
Simon Waddell
airliner was a Trident, with a 'T'-tail configuration. This particular
design (Ibeleiev in common with other T-tail designs) was able to get into a
stabe deep-stall configration where the nose rises so high that the
elevators descend into the wing wake and no longer have the authority to
lower the nose and the aircarft just pancakes down. Give enough height, I
think it is is possible to use the undercarriage and flaps to create enough
drag to correct the situation. These poor people didn't have the height
required.
"Mike Lindsay" <mi...@sailplane.demon.co.uk> wrote in message
news:Tey7obAoXpt$Ew...@sailplane.demon.co.uk...
303pilot
"Don Johnstone" <REMOVE_TO...@bittering.gioserve.com> wrote in
message news:bp0neh$1j6s5h$1...@ID-49798.news.uni-berlin.de...
> ATPL pilots in the cockpit, two of them qualified as
> captain on type. None of them it would appear recognised
> that the airplane was stalled.
> What chance have we mere mortals got if the gods get
> it wrong?
speaker whose business is teaching unusual attitude recovery to ATPLs. To
get his presentation going he gave us a number of scenarios and asked how
we'd respond. After giving us half a dozen of these and having the group
respond in unison with the right answer to each of them, he said "you know
more about this subject than any group of airline pilots I've ever trained".
Most of us glider pilots have a gut reaction in bad situations to unload the
wings first. Many professional pilots apparently don't.
That said, I don't mean to congratulate us all into any reduction in stall
avoidance and recovery training.
Robert John
Your explanation sounds plausible but bears no relation
to the accident investigation report. As far as I
know, the nose never got high - they would have realised
this, but it did get into the wrong configuration.
They could have recovered if they had (a) realised
the droop was retracted and put it down again, (b)
let the system do it's job (stick shaker warned them
and stick push tried to correct it but they dumped
it) or (c) initiated a normal stall recovery - lower
the nose - gain speed.
They were too slow at every stage of the flight and
somehow got into the wrong configuration, all of which
was 'probably' due to the Captain's partial incapacity
due to a heart attack and the crew not realising the
Captain's problem.
I suspect you were recalling a different incident in
a similar aircraft?
Rob
>In this particular case, they all recognised the airliner
>was stalled. The
>airliner was a Trident, with a 'T'-tail configuration.
> This particular
>design (Ibeleiev in common with other T-tail designs)
>was able to get into a
>stabe deep-stall configration where the nose rises
>so high that the
>elevators descend into the wing wake and no longer
>have the authority to
>lower the nose and the aircarft just pancakes down.
> Give enough height, I
>think it is is possible to use the undercarriage and
>flaps to create enough
>drag to correct the situation. These poor people didn't
>have the height
>required.
>
>news:Tey7obAoXpt$Ew...@sailplane.demon.co.uk...
>> >The final turn stall/spin claims many every year.
>>>Are
>> >we really approaching the problem in the right way?
>> >As an aside it is not just glider pilots who get it
>> >wrong. I recall reading an accident report of an airliner
>> >which had taken off from Heathrow back in the 60's
>> >or 70's. The aircraft stalled at about 3000ft and
>>>hit
>> >ATPL pilots in the cockpit, two of them qualified
>>>as
>> >captain on type. None of them it would appear recognised
>> >that the airplane was stalled.
>> >What chance have we mere mortals got if the gods get
>> >it wrong?
>> >
>> >
Simon Waddell
report. The human factors in the accident (probable heart attack attack,
junior crew member etc) were as stated. The initial cause of the problem
was raising the droop instead of the undercarriage (a). Re-reading the
report, I see it was the autopilot that caused the initial pitch up to
compensate for the loss/change of lift, but it was the pilot who switched
off the stick shaker and the stall recovery system, provoking the fatal
rapid pitch up (b). The design intent of the stick shaker was to ensure
that no pilot ever got into a deep stall unintentionally. The aircraft did
go into a deep stall and, because of the problems associated with its T-tail
configuration, initiating a normal stall recovery wasn't possible because
the elevators had lost their effectiveness in the wing turbulence.
Maybe putting the droops down again would have saved them, and/or flaps
and/or undercarriage.
As in so many accidents (eg the DC-10 at O'Hare), the pilots didn't actually
know what the problem was and didn't have the time or height to find out.
"Robert John" <REMOVE_TO_R...@robertjohnassociates.com> wrote in
message news:bpcqpf$1l5li2$1...@ID-49798.news.uni-berlin.de...