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IDAHO FATALITY



 
 
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  #121  
Old September 7th 11, 03:29 PM posted to rec.aviation.soaring
Dan Marotta
external usenet poster
 
Posts: 4,601
Default IDAHO FATALITY

Interviewing the surviving pilot after a stall/spin crash in a glider
equipped with "modern" instruments:

"What happened? Didn't you notice the quiet? The slack controls? The nose
dropping? Slicing?"

"Well, no... There was this annoying, distracting, loud buzzing going on
and I was trying to figure out what it meant when the lights went out."

Maybe we also need an interlock system which prevents opening the release
with weight on the wheel and spoilers or canopy unlocked... Then you
couldn't hook up until properly configured. For motorgliders, the engine
won't start until the configuration is correct for takeoff.


"kirk.stant" wrote in message
...
On Sep 5, 7:54 pm, Mike Schumann
wrote:
I am not against all "gadgets". I just think that we need to
prioritize, given the limited amount of panel space, and equally
importantly, the limited ability of people to learn how to use all the
stuff they are putting into their cockpits.


I agree with respect to a lot of the fancy PNA programs - they have
the potential to display so much useless info!

However, we were discussing stick shakers/stall warning systems
specifically - which are pretty bone-simple - even a caveman can
understand how they work!

At the top of my list would be collision avoidance gear (PowerFlarm /
ADS-B / transponder type stuff). This will potentially save a properly
trained pilot. My personal feeling is that you really aren't trained
properly if you can't sense and feel a stall coming on and don't
instinctively know what to do about it. Adding another instrument to
tell you what you should already know, just adds another item to your
scan, which distracts you from more important stuff, like looking for
traffic.


Apparently the FAA, NASA, Air Force, Boeing, Airbus, and airlines do
not share you opinion...

Modern gliders give very little indications of a stall (another reason
why training in old clunkers like the 2-33 is counterproductive). Add
a little distraction or a higher priority task (Bee in the cockpit!)
and you can be in a high-AOA situation without being aware of it. Add
to that a pilot who flies infrequently, and the benefit of a stall
warning system becomes even more clear.

Kirk
66

  #122  
Old September 7th 11, 03:29 PM posted to rec.aviation.soaring
Bill D
external usenet poster
 
Posts: 746
Default IDAHO FATALITY

On Sep 7, 1:46*am, Darryl Ramm wrote:
On 9/1/11 2:44 PM, Bill D wrote:
[snip]

This is yet another case where an angle of attack indicator with stall
warning stick vibrator would have saved a life. *Tiny cellphone/pager
vibrator motors embedded in the stick grip would be an excellent stall
warning.


I have no idea how you know enough about what was going on with the
aircraft and its pilot (especially inside his head/his perception of the
aircraft situation and flight performance) to know he would have
responded to a stall warning device appropriately and in time to
prevented the crash.

I would like to think maybe there is a stall warning device that might
be developed but I am pessimistic about the effectiveness of these
devices and false alarms while thermalling. And I am a bit bemused by
the mention a *small cellphone like shaker device to vibrate the control
stick. Many of our gliders give us some pretty good signals about an
impending stall. And in situations like where people are being killed in
pull-up/turn or flat over-rudder turns to base etc. I expect these
accident pilots are so far behind their aircraft that a subtle warnings
(e.g. vibrating the stick with a small shaker) would not be noticed. A
loud alarm or voice alert might at least have a chance of registering at
all with the pilot but whether the warning can be issued to allow them
enough time to react and whether the pilot will react correctly who
knows... (e.g. in a heading towards the dirt "ground rush" situations
the pilot has to sort out an audible stall alert vs. a pretty strong
visual cue that causes them to likely want to pull back and its not
clear what they will do).

I suspect something that is going to help the pilot who is well behind
their glider will require fairly loud/very obvious warning with a decent
pre-stall margin and that risks being annoying when thermalling slow.
e.g. its unclear if a system would be airspeed or AoA based, but
spoilers open often increase stall speeds *by a few knots so does the
stall warning need to know the spoiler position and factor this or do
you just pad the stall warning by a few more knots and further increase
false alarms/disturbances when thermalling? Flap position needs to be
factored as well on flapped gliders. If somebody is far enough behind
the glider and doing something that is about to bite them then how much
warning margin before the stall is actually needed to give the pilot a
good chance of avoiding or recovering faster/more effectively from the
stall/spin? Will those warning margins added together cause lots of
false alerts when thermalling say 10 knots above the stall in a gusty
thermal? And although I want something really obvious like a loud beep
or similar for a stall warning I also don't want noises that might be
confused with a FLARM/PowerFLARM alert while in a thermal.

There are glider stall warning systems available today, so the the
question may really be how do these systems work in practice and why are
there not more of them in use. DG built a visual and audible stall
warning system in the DG-600 and they have a stall warning in the DEI-NT
(and DEI??).

Safe Flight have their vane driven AoA meter which has an audible alarm
but besides seeing one installed in a glider at the SSA show in
Albuquerque a few years ago I have never hear of one of these installed
in the wild, or of a glider manufacturer offering these as options.
Anybody know any different? Or know what these cost? I believe the
fairly large vane is removable but how easy is it to damage e.g. on
ground handling?

The Cambridge 302 *has a stall warning based on pitot airspeed, wing
loading (it knows the % ballast) and G-meter (but it does not take into
effect flap or spoiler position). I used a C302 in my DG-303 and ASH-26E
and in both cases turned down the warning airspeed because it produced
too many false alarms while thermalling, based on my own use I don't
think its a useful tool for real stall/spin avoidance. Other pilot's
have experiences/opinions with the C302 stall warning?

So who has actually flies with any of these or other stall warning
indicators today and how useful have they found them? And do you think
they will be useful for preventing some of the
behind-the-aircraft/confused pilot stall/spin accidents we've seen?

I know there are these videos on YouTube athttp://www.youtube.com/user/DT38000?blend=23&ob=5, I assume showing the
DG DEI system alerting but without more information like the airspeeds
and seeing the glider thermalling I can't really draw any conclusion at
all from the videos.

In the meantime, looks like instructors doing BFRs and spring checkouts
next year have lots and lots of stuff to go through that may save
lives... from tow-signals to stall/spin aerodynamics, recognition and
recovery.

Darryl


How do I know it works? Because it works and is therefore considered
essential in hundreds of thousands of airplanes.

So, what solution do you propose?

I'm trying to think of ways to save lives. What is your objective?

The "lets train them better" idea has been around 100 years with
generally dismal results. The stall warning device idea has been
around probably 50 years and works well enough it has been widely
adopted throughout the aviation world. Only the gliding world has
successfully resisted stall warning devices and we pay for it in our
accident record.

Stall sensors could be either airspeed or AoA based. A simple and
rugged sensor is a pair of pressure ports on the top and bottom of the
nose cone. The differential pressure between these ports is
proportional to AoA.

Would there be false warnings? Of course there would. It happens on
light airplanes but there's no confusion since a intermittent warning
in rough air has an obvious and benign cause. A steady warning at low
airspeed signals an impending stall. If an AoA display is part of the
system, a glance at it would show the cause of a warning.

It's also possible to set sensitivity depending on the phase of
flight. If the gear is down signaling an impending landing, the
warning could be more sensitive sounding at a lower AoA/higher
airspeed. Our computers detect thermalling and set themselves to that
mode automatically - they could also set the stall warning to be less
sensitive when thermalling.

If a stick vibrator isn't sufficient, adding a bright light to the
glare shield or audible warning would be easy. It could even be set
so the vibration starts early to be followed by a loud warning if the
dangerously high AoA condition persists. This could avoid annoying an
attentive pilot while providing an unmistakeable warning to the
distracted pilot.

It is so easy for people to set back and think of reasons why
something might not work while never putting forward one which would
work. They never have to prove an idea won't work, they just raise
doubts by suggesting it might not work perfectly every time. They're
called "Negative Experts".

A stall warning device doesn't have to work every time. If it saves a
life 10% of the time it would be worthwhile. Good research says it
will work far more often than that.

  #123  
Old September 7th 11, 04:17 PM posted to rec.aviation.soaring
Jim White[_3_]
external usenet poster
 
Posts: 286
Default Stall Warnings

Upon reflection I think this device might be really helpful. It would allow
me to fly much closer to the stall without having to think too much when
thermalling and landing. I could just keep pulling until I feel the buzz.
Might still have a problem when I am doing a wing over after a high energy
inverted pass however.

Well trained and practised glider pilots are completely comfortable with
the stall and spin characteristics of their glider(s). Whenever I return to
base high I take the opportunity to stall / spin / and bat my glider to
improve my handling skill and my familiarity with its flight
characteristics. It is also great fun.

In the UK we train pilots to recognise and recover stalls, spins, and
spiral dives before they go solo. Solo pilots at my club are also
encouraged to learn aerobatics to improve their handling and awareness of
the aircraft. Like unclhank, I do not think we should replace training with
gadgets.

Jim

ps: I watched a chap in a brand new Mercedes back into a table yesterday
producing a huge and expensive dent. He had reversing sensors but they
clearly weren't pointing at the table and he new he could rely upon them
because that's what the salesman had said!



At 14:29 07 September 2011, Bill D wrote:

How do I know it works? Because it works and is therefore considered
essential in hundreds of thousands of airplanes.

So, what solution do you propose?

I'm trying to think of ways to save lives. What is your objective?

The "lets train them better" idea has been around 100 years with
generally dismal results. The stall warning device idea has been
around probably 50 years and works well enough it has been widely
adopted throughout the aviation world. Only the gliding world has
successfully resisted stall warning devices and we pay for it in our
accident record.

Stall sensors could be either airspeed or AoA based. A simple and
rugged sensor is a pair of pressure ports on the top and bottom of the
nose cone. The differential pressure between these ports is
proportional to AoA.

Would there be false warnings? Of course there would. It happens on
light airplanes but there's no confusion since a intermittent warning
in rough air has an obvious and benign cause. A steady warning at low
airspeed signals an impending stall. If an AoA display is part of the
system, a glance at it would show the cause of a warning.

It's also possible to set sensitivity depending on the phase of
flight. If the gear is down signaling an impending landing, the
warning could be more sensitive sounding at a lower AoA/higher
airspeed. Our computers detect thermalling and set themselves to that
mode automatically - they could also set the stall warning to be less
sensitive when thermalling.

If a stick vibrator isn't sufficient, adding a bright light to the
glare shield or audible warning would be easy. It could even be set
so the vibration starts early to be followed by a loud warning if the
dangerously high AoA condition persists. This could avoid annoying an
attentive pilot while providing an unmistakeable warning to the
distracted pilot.

It is so easy for people to set back and think of reasons why
something might not work while never putting forward one which would
work. They never have to prove an idea won't work, they just raise
doubts by suggesting it might not work perfectly every time. They're
called "Negative Experts".

A stall warning device doesn't have to work every time. If it saves a
life 10% of the time it would be worthwhile. Good research says it
will work far more often than that.



  #124  
Old September 7th 11, 04:48 PM posted to rec.aviation.soaring
Bill D
external usenet poster
 
Posts: 746
Default Stall warnings

On Sep 7, 8:01*am, wrote:
On Sep 6, 3:35*pm, Ramy wrote:









On Sep 6, 8:11*am, Jim White wrote:


I have changed the subject as we are well passed Idaho now.


I am having trouble with this stall warning stuff. I fly modern gliders:
ASW27, Duo Discus, ASK21 etc. All give clear warnings ahead of a stall.
When they do stall the nose drops, stick forward a bit, dada...stall
recovered. If they were to start into a spin (and the 21 shouldn't with
normal C of G positions), stick forward a bit, maybe a bit of pedal, and
dada...recovered.
None would lose significant amounts of height if recovered straight away.


I compete in the 27 and regularly fly it in thermals near the stall. You
feel for the break in laminar flow on the wings. This actually happens well
before the stall. It would be impossible to climb effectively if the stick
kept shaking!


And what would happen in a fully held off landing? I would also be a bit
****ed if the shaker went off when I was landing as slow as possible into a
very tight field in a light head wind!


This has to be about training and currency in gliders. We are not flying
747s with passengers down the back.


Final turns should be made at a sensible height with sufficient speed and
well banked so that they cannot be ruddered into a spin. This all should be
natural and obvious to a well trained pilot. No need for another mechanical
gadget to go wrong.


At 13:00 06 September 2011, kirk.stant wrote:


Modern gliders give very little indications of a stall (another reason
why training in old clunkers like the 2-33 is counterproductive). *Add
a little distraction or a higher priority task (Bee in the cockpit!)
and you can be in a high-AOA situation without being aware of it. *Add
to that a pilot who flies infrequently, and the benefit of a stall
warning system becomes even more clear.


Kirk
66- Hide quoted text -


- Show quoted text -


This is the point that puzzles me the most. I am sure that many of us
had never accidentally stalled/spinned a glider even in rough
thermals, due to the ample warnings. Incipient spin is the closest to
accidental spin I ever got, and this is only when grossly skidding in
rough thermal at safe altitude. Yet the majority of glider accidents
are attributed to stall/spin, and usually very experienced pilots, and
if my assumption above is correct, it was probably their first
accidental stall/spin. Which leads me to conclude that those stall/
spin happened without warning from one reason or another.
I think it will be very helpful to hear stories from pilots who
survived a stall/spin accident, and why they think it happened.
Anyone on RAS who survived such an accident care to share their story?


Ramy- Hide quoted text -


- Show quoted text -


I'm going out on a limb here and somebody out there will get the saw
out.
A stall does not happen without some warning.
The important element in training is understanding the warning signs.
I teach 6 signs and require all pilots I oversee to be able to
verbalize and demonstrate them.
#1- Reduced control effectiveness sensed by lower resistance to forces
applied by the pilot and reduced response of the glider.
#2- Nose high attitude. Yes we can stall at any attitude, but nose
high is almost always there in critical stalls.
#3- Reduced cockpit noise- Less noticable in modern gliders but still
evident.
#4- Stick pressure is back and likely significant- Exception is aft CG
or improperly trimmed glider.
#5- Low indicated air speed
#6- Buffet indicating flow separation preceding a stall.
It is worth noting that pilots previously trained in airplanes will
commonly mention #6 first , but almost none have been trained on the
other warnings.
I also note that the majority of pilots I check that have been trained
by others have a few (maybe a half dozen or so) log book entries
noting stalls. This, in my view, is completely inadequate. Recognition
and response must be automatic and instinctive, and this needs much
more emphasis and practice.
Off soap box
UH


Excellent review!

I would only add if one or more of these symptoms are present and a
stall warning sounds, it will be clear why it sounded. A stall
warning tends to provide the impetus for action - merely recognizing
the symptoms does not in itself result in stall/spin avoidance - the
pilot must act to lower the AoA.
  #125  
Old September 7th 11, 05:10 PM posted to rec.aviation.soaring
Darryl Ramm
external usenet poster
 
Posts: 2,403
Default IDAHO FATALITY

Bill D wrote:
On Sep 7, 1:46 am, Darryl Ramm wrote:
On 9/1/11 2:44 PM, Bill D wrote:
[snip]

This is yet another case where an angle of attack indicator with
stall
warning stick vibrator would have saved a life. Tiny
cellphone/pager
vibrator motors embedded in the stick grip would be an excellent
stall
warning.


I have no idea how you know enough about what was going on with the
aircraft and its pilot (especially inside his head/his perception of
the
aircraft situation and flight performance) to know he would have
responded to a stall warning device appropriately and in time to
prevented the crash.

I would like to think maybe there is a stall warning device that
might
be developed but I am pessimistic about the effectiveness of these
devices and false alarms while thermalling. And I am a bit bemused
by
the mention a small cellphone like shaker device to vibrate the
control
stick. Many of our gliders give us some pretty good signals about an
impending stall. And in situations like where people are being
killed in
pull-up/turn or flat over-rudder turns to base etc. I expect these
accident pilots are so far behind their aircraft that a subtle
warnings
(e.g. vibrating the stick with a small shaker) would not be noticed.
A
loud alarm or voice alert might at least have a chance of
registering at
all with the pilot but whether the warning can be issued to allow
them
enough time to react and whether the pilot will react correctly who
knows... (e.g. in a heading towards the dirt "ground rush"
situations
the pilot has to sort out an audible stall alert vs. a pretty strong
visual cue that causes them to likely want to pull back and its not
clear what they will do).

I suspect something that is going to help the pilot who is well
behind
their glider will require fairly loud/very obvious warning with a
decent
pre-stall margin and that risks being annoying when thermalling
slow.
e.g. its unclear if a system would be airspeed or AoA based, but
spoilers open often increase stall speeds by a few knots so does
the
stall warning need to know the spoiler position and factor this or
do
you just pad the stall warning by a few more knots and further
increase
false alarms/disturbances when thermalling? Flap position needs to
be
factored as well on flapped gliders. If somebody is far enough
behind
the glider and doing something that is about to bite them then how
much
warning margin before the stall is actually needed to give the pilot
a
good chance of avoiding or recovering faster/more effectively from
the
stall/spin? Will those warning margins added together cause lots of
false alerts when thermalling say 10 knots above the stall in a
gusty
thermal? And although I want something really obvious like a loud
beep
or similar for a stall warning I also don't want noises that might
be
confused with a FLARM/PowerFLARM alert while in a thermal.

There are glider stall warning systems available today, so the the
question may really be how do these systems work in practice and why
are
there not more of them in use. DG built a visual and audible stall
warning system in the DG-600 and they have a stall warning in the
DEI-NT
(and DEI??).

Safe Flight have their vane driven AoA meter which has an audible
alarm
but besides seeing one installed in a glider at the SSA show in
Albuquerque a few years ago I have never hear of one of these
installed
in the wild, or of a glider manufacturer offering these as options.
Anybody know any different? Or know what these cost? I believe the
fairly large vane is removable but how easy is it to damage e.g. on
ground handling?

The Cambridge 302 has a stall warning based on pitot airspeed, wing
loading (it knows the % ballast) and G-meter (but it does not take
into
effect flap or spoiler position). I used a C302 in my DG-303 and
ASH-26E
and in both cases turned down the warning airspeed because it
produced
too many false alarms while thermalling, based on my own use I don't
think its a useful tool for real stall/spin avoidance. Other pilot's
have experiences/opinions with the C302 stall warning?

So who has actually flies with any of these or other stall warning
indicators today and how useful have they found them? And do you
think
they will be useful for preventing some of the
behind-the-aircraft/confused pilot stall/spin accidents we've seen?

I know there are these videos on YouTube
athttp://www.youtube.com/user/DT38000?blend=23&ob=5, I assume
showing the
DG DEI system alerting but without more information like the
airspeeds
and seeing the glider thermalling I can't really draw any conclusion
at
all from the videos.

In the meantime, looks like instructors doing BFRs and spring
checkouts
next year have lots and lots of stuff to go through that may save
lives... from tow-signals to stall/spin aerodynamics, recognition
and
recovery.

Darryl


How do I know it works? Because it works and is therefore considered
essential in hundreds of thousands of airplanes.

So, what solution do you propose?

I'm trying to think of ways to save lives. What is your objective?

The "lets train them better" idea has been around 100 years with
generally dismal results. The stall warning device idea has been
around probably 50 years and works well enough it has been widely
adopted throughout the aviation world. Only the gliding world has
successfully resisted stall warning devices and we pay for it in our
accident record.

Stall sensors could be either airspeed or AoA based. A simple and
rugged sensor is a pair of pressure ports on the top and bottom of the
nose cone. The differential pressure between these ports is
proportional to AoA.

Would there be false warnings? Of course there would. It happens on
light airplanes but there's no confusion since a intermittent warning
in rough air has an obvious and benign cause. A steady warning at low
airspeed signals an impending stall. If an AoA display is part of the
system, a glance at it would show the cause of a warning.

It's also possible to set sensitivity depending on the phase of
flight. If the gear is down signaling an impending landing, the
warning could be more sensitive sounding at a lower AoA/higher
airspeed. Our computers detect thermalling and set themselves to that
mode automatically - they could also set the stall warning to be less
sensitive when thermalling.

If a stick vibrator isn't sufficient, adding a bright light to the
glare shield or audible warning would be easy. It could even be set
so the vibration starts early to be followed by a loud warning if the
dangerously high AoA condition persists. This could avoid annoying an
attentive pilot while providing an unmistakeable warning to the
distracted pilot.

It is so easy for people to set back and think of reasons why
something might not work while never putting forward one which would
work. They never have to prove an idea won't work, they just raise
doubts by suggesting it might not work perfectly every time. They're
called "Negative Experts".

A stall warning device doesn't have to work every time. If it saves a
life 10% of the time it would be worthwhile. Good research says it
will work far more often than that.


Good research? What research?

You can hand wave all you want about what might work. But there are
systems out there today--how they work and why they seemingly have not
been adopted are likely worth understanding. Especially if something out
there actually works well then the problem is understanding what is
holding back adoption and that would be a great problem to solve. If
these systems, which have been built by sone pretty skilled folks, don't
work well in practice then that is not encouraging that the problem is
easilly solvable.

My goal is to help avoid accidents like we are seeing and like I said if
a stall warning box could be developed that worked well (esp. few false
alarms) then that is great. But without those boxes known to work
well/be available now I would rather see focus on what seems like some
unfortunately poor flying skills.

Could a stall warning system help save lives? Of course it could but it
is simply impossible to make absolute claims about avoiding a particular
fatal accident. There are many crashes in aircraft where the pilot has
been confused or ignored stall warnings/shakers or fought the stick
pusher. There is no way of knowing what adding a stall warning alert to
a particular accident will do to a pilot who is already behind the
aircraft/confused and facing a variety of what may be in their mind
conflicting signals.

So any more reports from folks who fly with existing stall warning
devices? Any reports on the DG DEI boxes? Anybody know if DG ever
offered this current stall warning system packaged outside the engine
controller (the DG-600 used a different system)?

Darryl
  #126  
Old September 7th 11, 07:08 PM posted to rec.aviation.soaring
Mike Schumann
external usenet poster
 
Posts: 539
Default Stall warnings

On 9/7/2011 9:01 AM, wrote:
On Sep 6, 3:35 pm, wrote:
On Sep 6, 8:11 am, Jim wrote:





I have changed the subject as we are well passed Idaho now.


I am having trouble with this stall warning stuff. I fly modern gliders:
ASW27, Duo Discus, ASK21 etc. All give clear warnings ahead of a stall.
When they do stall the nose drops, stick forward a bit, dada...stall
recovered. If they were to start into a spin (and the 21 shouldn't with
normal C of G positions), stick forward a bit, maybe a bit of pedal, and
dada...recovered.
None would lose significant amounts of height if recovered straight away.


I compete in the 27 and regularly fly it in thermals near the stall. You
feel for the break in laminar flow on the wings. This actually happens well
before the stall. It would be impossible to climb effectively if the stick
kept shaking!


And what would happen in a fully held off landing? I would also be a bit
****ed if the shaker went off when I was landing as slow as possible into a
very tight field in a light head wind!


This has to be about training and currency in gliders. We are not flying
747s with passengers down the back.


Final turns should be made at a sensible height with sufficient speed and
well banked so that they cannot be ruddered into a spin. This all should be
natural and obvious to a well trained pilot. No need for another mechanical
gadget to go wrong.


At 13:00 06 September 2011, kirk.stant wrote:


Modern gliders give very little indications of a stall (another reason
why training in old clunkers like the 2-33 is counterproductive). Add
a little distraction or a higher priority task (Bee in the cockpit!)
and you can be in a high-AOA situation without being aware of it. Add
to that a pilot who flies infrequently, and the benefit of a stall
warning system becomes even more clear.


Kirk
66- Hide quoted text -


- Show quoted text -


This is the point that puzzles me the most. I am sure that many of us
had never accidentally stalled/spinned a glider even in rough
thermals, due to the ample warnings. Incipient spin is the closest to
accidental spin I ever got, and this is only when grossly skidding in
rough thermal at safe altitude. Yet the majority of glider accidents
are attributed to stall/spin, and usually very experienced pilots, and
if my assumption above is correct, it was probably their first
accidental stall/spin. Which leads me to conclude that those stall/
spin happened without warning from one reason or another.
I think it will be very helpful to hear stories from pilots who
survived a stall/spin accident, and why they think it happened.
Anyone on RAS who survived such an accident care to share their story?

Ramy- Hide quoted text -

- Show quoted text -


I'm going out on a limb here and somebody out there will get the saw
out.
A stall does not happen without some warning.
The important element in training is understanding the warning signs.
I teach 6 signs and require all pilots I oversee to be able to
verbalize and demonstrate them.
#1- Reduced control effectiveness sensed by lower resistance to forces
applied by the pilot and reduced response of the glider.
#2- Nose high attitude. Yes we can stall at any attitude, but nose
high is almost always there in critical stalls.
#3- Reduced cockpit noise- Less noticable in modern gliders but still
evident.
#4- Stick pressure is back and likely significant- Exception is aft CG
or improperly trimmed glider.
#5- Low indicated air speed
#6- Buffet indicating flow separation preceding a stall.
It is worth noting that pilots previously trained in airplanes will
commonly mention #6 first , but almost none have been trained on the
other warnings.
I also note that the majority of pilots I check that have been trained
by others have a few (maybe a half dozen or so) log book entries
noting stalls. This, in my view, is completely inadequate. Recognition
and response must be automatic and instinctive, and this needs much
more emphasis and practice.
Off soap box
UH


I think you need to be careful on how this is presented to students.
Many will interpret this to mean that all of these symptoms need to be
present during a stall.

In particular, the nose high attitude is not always there, particularly
in the type of stalls we see during landings. This is real obvious if
you start getting a little slow while thermalling. You can feel the
stall come on with the mushy controls and eventually the inside wing
starts to drop, but the nose isn't at any unusual attitude.


--
Mike Schumann
  #127  
Old September 7th 11, 07:26 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 2,124
Default Stall warnings

On Sep 7, 2:08*pm, Mike Schumann
wrote:
On 9/7/2011 9:01 AM, wrote:





On Sep 6, 3:35 pm, *wrote:
On Sep 6, 8:11 am, Jim *wrote:


I have changed the subject as we are well passed Idaho now.


I am having trouble with this stall warning stuff. I fly modern gliders:
ASW27, Duo Discus, ASK21 etc. All give clear warnings ahead of a stall.
When they do stall the nose drops, stick forward a bit, dada...stall
recovered. If they were to start into a spin (and the 21 shouldn't with
normal C of G positions), stick forward a bit, maybe a bit of pedal, and
dada...recovered.
None would lose significant amounts of height if recovered straight away.


I compete in the 27 and regularly fly it in thermals near the stall. You
feel for the break in laminar flow on the wings. This actually happens well
before the stall. It would be impossible to climb effectively if the stick
kept shaking!


And what would happen in a fully held off landing? I would also be a bit
****ed if the shaker went off when I was landing as slow as possible into a
very tight field in a light head wind!


This has to be about training and currency in gliders. We are not flying
747s with passengers down the back.


Final turns should be made at a sensible height with sufficient speed and
well banked so that they cannot be ruddered into a spin. This all should be
natural and obvious to a well trained pilot. No need for another mechanical
gadget to go wrong.


At 13:00 06 September 2011, kirk.stant wrote:


Modern gliders give very little indications of a stall (another reason
why training in old clunkers like the 2-33 is counterproductive). *Add
a little distraction or a higher priority task (Bee in the cockpit!)
and you can be in a high-AOA situation without being aware of it. *Add
to that a pilot who flies infrequently, and the benefit of a stall
warning system becomes even more clear.


Kirk
66- Hide quoted text -


- Show quoted text -


This is the point that puzzles me the most. I am sure that many of us
had never accidentally stalled/spinned a glider even in rough
thermals, due to the ample warnings. Incipient spin is the closest to
accidental spin I ever got, and this is only when grossly skidding in
rough thermal at safe altitude. Yet the majority of glider accidents
are attributed to stall/spin, and usually very experienced pilots, and
if my assumption above is correct, it was probably their first
accidental stall/spin. Which leads me to conclude that those stall/
spin happened without warning from one reason or another.
I think it will be very helpful to hear stories from pilots who
survived a stall/spin accident, and why they think it happened.
Anyone on RAS who survived such an accident care to share their story?


Ramy- Hide quoted text -


- Show quoted text -


I'm going out on a limb here and somebody out there will get the saw
out.
A stall does not happen without some warning.
The important element in training is understanding the warning signs.
I teach 6 signs and require all pilots I oversee to be able to
verbalize and demonstrate them.
#1- Reduced control effectiveness sensed by lower resistance to forces
applied by the pilot and reduced response of the glider.
#2- Nose high attitude. Yes we can stall at any attitude, but nose
high is almost always there in critical stalls.
#3- Reduced cockpit noise- Less noticable in modern gliders but still
evident.
#4- Stick pressure is back and likely significant- Exception is aft CG
or improperly trimmed glider.
#5- Low indicated air speed
#6- Buffet indicating flow separation preceding a stall.
It is worth noting that pilots previously trained in airplanes will
commonly mention #6 first , but almost none have been trained on the
other warnings.
I also note that the majority of pilots I check that have been trained
by others have a few (maybe a half dozen or so) log book entries
noting stalls. This, in my view, is completely inadequate. Recognition
and response must be automatic and instinctive, and this needs much
more emphasis and practice.
Off soap box
UH


I think you need to be careful on how this is presented to students.
Many will interpret this to mean that all of these symptoms need to be
present during a stall.

In particular, the nose high attitude is not always there, particularly
in the type of stalls we see during landings. *This is real obvious if
you start getting a little slow while thermalling. *You can feel the
stall come on with the mushy controls and eventually the inside wing
starts to drop, but the nose isn't at any unusual attitude.

--
Mike Schumann- Hide quoted text -

- Show quoted text -


Someplace in the 9000 or so training flights I've done I figured out
you don't need all of them.
I wasn't trying to give you the whole lesson on RAS.
The point was that there are, in fact, plenty of signs if pilots are
made sensitive to them.
As instructors, we need to continue to train better and really
emphasize this area in flight reviews.
The reason many pilots crash is they either don't recognize these
signals or ignore them.
A bit Crabby
UH
  #128  
Old September 7th 11, 07:52 PM posted to rec.aviation.soaring
jcarlyle
external usenet poster
 
Posts: 522
Default Stall warnings

Mike, I was waiting for UH to answer your primary concern. Now that he
has, am I correct in reading into your original question that this was
the first time you've seen someone present the six signs of an
impending stall?

-John

On Sep 7, 2:08 pm, Mike Schumann
wrote:
I think you need to be careful on how this is presented to students.
Many will interpret this to mean that all of these symptoms need to be
present during a stall.

In particular, the nose high attitude is not always there, particularly
in the type of stalls we see during landings. This is real obvious if
you start getting a little slow while thermalling. You can feel the
stall come on with the mushy controls and eventually the inside wing
starts to drop, but the nose isn't at any unusual attitude.

--
Mike Schumann


  #129  
Old September 7th 11, 08:08 PM posted to rec.aviation.soaring
BDS
external usenet poster
 
Posts: 127
Default Stall warnings

The problem with this theory is that there are plenty of airplanes out there
that are equipped with stall warning devices and that also exhibit exactly
the same 6 warning signs when a stall is imminent, and yet pilots still
manage to kill themselves in them after an accident preceded by a stall.
Apparently the stall warning device on top of the 6 other warnings that the
aircraft is screaming at the pilot isn't quite the impetus to action that it
might seem to be in theory.

Instructors will probably agree that they have seen times when a pilot is so
mentally loaded up that no amount of repeatedly telling them to take an
action appropriate to the situation at hand will be sufficient to resolve
the problem. Sometimes, the only solution is to take the controls
temporarily and correct the situation. Therefore, I suspect that if you are
so far behind the curve that you are unaware of all of the other signs of an
impending stall, that one more piled on top of all of the others will have
little or no effect on the outcome.



"Bill D" wrote in message
...

- Show quoted text -


I'm going out on a limb here and somebody out there will get the saw
out.
A stall does not happen without some warning.
The important element in training is understanding the warning signs.
I teach 6 signs and require all pilots I oversee to be able to
verbalize and demonstrate them.
#1- Reduced control effectiveness sensed by lower resistance to forces
applied by the pilot and reduced response of the glider.
#2- Nose high attitude. Yes we can stall at any attitude, but nose
high is almost always there in critical stalls.
#3- Reduced cockpit noise- Less noticable in modern gliders but still
evident.
#4- Stick pressure is back and likely significant- Exception is aft CG
or improperly trimmed glider.
#5- Low indicated air speed
#6- Buffet indicating flow separation preceding a stall.
It is worth noting that pilots previously trained in airplanes will
commonly mention #6 first , but almost none have been trained on the
other warnings.
I also note that the majority of pilots I check that have been trained
by others have a few (maybe a half dozen or so) log book entries
noting stalls. This, in my view, is completely inadequate. Recognition
and response must be automatic and instinctive, and this needs much
more emphasis and practice.
Off soap box
UH


Excellent review!

I would only add if one or more of these symptoms are present and a
stall warning sounds, it will be clear why it sounded. A stall
warning tends to provide the impetus for action - merely recognizing
the symptoms does not in itself result in stall/spin avoidance - the
pilot must act to lower the AoA.


  #130  
Old September 7th 11, 11:54 PM posted to rec.aviation.soaring
Mike Schumann
external usenet poster
 
Posts: 539
Default Stall warnings

On 9/7/2011 1:52 PM, jcarlyle wrote:
Mike, I was waiting for UH to answer your primary concern. Now that he
has, am I correct in reading into your original question that this was
the first time you've seen someone present the six signs of an
impending stall?

-John

On Sep 7, 2:08 pm, Mike
wrote:
I think you need to be careful on how this is presented to students.
Many will interpret this to mean that all of these symptoms need to be
present during a stall.

In particular, the nose high attitude is not always there, particularly
in the type of stalls we see during landings. This is real obvious if
you start getting a little slow while thermalling. You can feel the
stall come on with the mushy controls and eventually the inside wing
starts to drop, but the nose isn't at any unusual attitude.

--
Mike Schumann


Why would you assume that? My point is that not each of these signs is
always present when you enter a stall. When you teach stall recognition
to students, they need to be able to sense the stall coming on
regardless of the aircraft attitude and other factors.

--
Mike Schumann
 




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