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Nimbus 4DT accident 31 July 2000 in Spain.



 
 
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  #21  
Old June 21st 05, 11:34 PM
Mark Dickson
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I've read your entries, MB, and, in common with Stefan,
have been dismayed by your comments on recognising
and recovering from spins and spiral dives. Rather
than teaching these exercises and trying to impart
your 'knowledge' on this forum, you should have a bit
of remedial instruction yourself. Your reactions to
spinning should be automatic, there should be absolutely
no need to check your ASI to see if your spinning or
in a spiral dive. If you are in a spin you should
positively move the stick forward, not 'release the
back pressure'. Releasing the back pressure at the
buffet should prevent a spin developing.



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  #22  
Old June 22nd 05, 05:30 AM
Kilo Charlie
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"Eric Greenwell" wrote in message
...
M B wrote:


Don't the controls feel differently at 30 knots and 100 knots? That should
be a good clue as you begin the spin recovery.


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State


I am a partner in a Nimbus 3D. I have not had a lot of time in it but have
flown aircraft of all kinds for 36 years including hundreds of glider and
powered aerobatic hours. In order to get the Nimbus to go beyond the green
arc it takes a very large amount of forward stick even with the trim all the
way to the forward stop.....with flaps in -2. I absolutely disagree that it
would be easy to let it get away from you and end up in a spiral with the
exception of possibly entering it from a spin. The spin enty on the other
hand is docile and easy to recover from. As has been pointed out, if one is
clueless re incipient spins then the scenario in these 2 accidents might
easily unfold. Only education, planning and practice will prevent similar
accidents.

Casey Lenox
KC
Phoenix


  #23  
Old June 22nd 05, 05:32 AM
mev
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Crap Mark, do you think before you press *send*? It rarely seems so.


Mark Dickson wrote:
I've read your entries, MB, and, in common with Stefan,
have been dismayed by your comments on recognising
and recovering from spins and spiral dives. Rather
than teaching these exercises and trying to impart
your 'knowledge' on this forum, you should have a bit
of remedial instruction yourself. Your reactions to
spinning should be automatic, there should be absolutely
no need to check your ASI to see if your spinning or
in a spiral dive. If you are in a spin you should
positively move the stick forward, not 'release the
back pressure'. Releasing the back pressure at the
buffet should prevent a spin developing.



  #24  
Old June 22nd 05, 09:42 AM
Don Johnstone
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I see nothing crap in Mark's post. Could you perhaps
explain?

At 04:48 22 June 2005, Mev wrote:
Crap Mark, do you think before you press *send*? It
rarely seems so.


Mark Dickson wrote:
I've read your entries, MB, and, in common with Stefan,
have been dismayed by your comments on recognising
and recovering from spins and spiral dives. Rather
than teaching these exercises and trying to impart
your 'knowledge' on this forum, you should have a
bit
of remedial instruction yourself. Your reactions
to
spinning should be automatic, there should be absolutely
no need to check your ASI to see if your spinning
or
in a spiral dive. If you are in a spin you should
positively move the stick forward, not 'release the
back pressure'. Releasing the back pressure at the
buffet should prevent a spin developing.







  #25  
Old June 22nd 05, 01:54 PM
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KC, yup.

I wonder at the thread though. Everyone discussing recognition of a
fully developed spin versus spiral dive.

Years ago, Al Blackburn pointed out to me that long span gliders need
to be treated gingerly at speed. His concern had to do with the
application of aileron during dive recovery. While he felt that most
pilots could manage the elevator to avoid structural damage, aileron
asymmetry (and the resulting squatcheloid assymetry) presented a
complicating factor. The longer the span, the more critical its
effects. Add a partial load of water, a yaw moment, and/or spoiler caps
deploying with wing bend and it's not hard to see how things might
quickly get to the breaking point.

  #26  
Old June 22nd 05, 02:33 PM
Bert Willing
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As long as a 26m glider is certified under JAR22, there is no issue of
control inputs versus speed other than for a 15m glider.

What changes drastically with a long wing is the entry into a spin or a
spiral dive. The long wing makes that you can have large discrepancies of
effective angle of attack along the wingspan (which can make the spin entry
under g-load quite interesting). Long wings also have much more angular
momentum once the spin/spiral dive is developped - it can be as much as 5
times the angular momentum of a 15m glider, and that makes that recovery
will take a certain time even if correct counter procedures are undertaken.
And during that time, the glider will accelerate like hell so that you are
likely to operate you final recovery well beyond what's written in the
flight manual.

I think that training of instant recovery of a spin entry (or spiral dive
entry) is mandatory if you want to fly a 25+m ship safely. But in contrary
to short wings, it would be plain stupid to train the recovery of a fully
developed spin/spiral dive in these ships (beyond fligh testing for
certification) and that's the reason that a flight manual will usually call
it illegal.

Been there, done it, and don't feel that I want to get there again.
--
Bert Willing

ASW20 "TW"


a écrit dans le message de news:
...
KC, yup.

I wonder at the thread though. Everyone discussing recognition of a
fully developed spin versus spiral dive.

Years ago, Al Blackburn pointed out to me that long span gliders need
to be treated gingerly at speed. His concern had to do with the
application of aileron during dive recovery. While he felt that most
pilots could manage the elevator to avoid structural damage, aileron
asymmetry (and the resulting squatcheloid assymetry) presented a
complicating factor. The longer the span, the more critical its
effects. Add a partial load of water, a yaw moment, and/or spoiler caps
deploying with wing bend and it's not hard to see how things might
quickly get to the breaking point.



  #27  
Old June 22nd 05, 05:32 PM
For Example John Smith
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"the resulting squatcheloid assymetry"?
What the heck is that?
Anything like the yeti dihedral?

wrote in message
ups.com...
KC, yup.

I wonder at the thread though. Everyone discussing recognition of a
fully developed spin versus spiral dive.

Years ago, Al Blackburn pointed out to me that long span gliders need
to be treated gingerly at speed. His concern had to do with the
application of aileron during dive recovery. While he felt that most
pilots could manage the elevator to avoid structural damage, aileron
asymmetry (and the resulting squatcheloid assymetry) presented a
complicating factor. The longer the span, the more critical its
effects. Add a partial load of water, a yaw moment, and/or spoiler caps
deploying with wing bend and it's not hard to see how things might
quickly get to the breaking point.



  #28  
Old June 22nd 05, 05:52 PM
M B
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I'm not as interested in spins and spirals. This is
important, but covered adequately already on RAS and
elsewhere.

To me, I'm more interested in the less commonly discussed
human factors. Specifically what factors contribute
to accidents?

Both Eric and Bert's posts made me think about some
things
along with what Stefan and Casey wrote.

In my experience, I have seen and been a part of confusion
in
the cockpit. One pilot is saying one thing and the
other is
contradicting it. I've also had both pilots on the
controls at the same time, with opposite pressures
applied.

I've seen and felt myself during critical moments both
a
narrowing of perceptions and a loss of sense of time.
Seconds seem like hours and vice versa. In aerobatic
training,
the focus was not on control inputs, but correctly
applying
the RATE of control changes.

I've also noted that I use trim extensively when flying,
and this
reduces the feedback I get about airspeed from the
stiffness of
the elevator controls. Casey wrote about how trim
(and maybe flaps) change the behavior of a spin, and
require different control pressures. Flaps, water,
a second passenger, trim,
quite a different 'feel' depending on these factors.


Bert mentioned that training in fully developed spins
in one of these ships might be (ahem) hard to find.
And what ships are similar to these which ARE certified
for full spin training?

If I put all these observations into this accident,
the
post-accident debrief reads as a bit of fiction, none
of
which is in either of the real accident reports:

*****fictional report begins****

We were tight in a thermal, with my dad at the controls.
It was bumpy, and the vario was turned up loud and
beeping.
I was scanning for traffic over my shoulder, and my
dad
was telling a story. When I looked forward, we were
nose down.
I said 'I got it' and took the controls. I was trying
to pull back but something was stopping the stick,
so I paused
for a second. My dad said 'it's spinning!' again and
again very loud.
I think he may have been trying to push forward while
I was pulling.
Between the vario, his yelling, and me thinking about
the flap lever,
I don't remember hearing any airspeed indications.

I glanced at the wrap-around ASI, and couldn't tell
if we were stalling or
going through 140kts. I wasn't the one who'd done
the trim, so
I couldn't tell if the pressures were light on the
elevator or
if that was just trim. I was distracted by my Dad's
yelling.

It had been a while since I had done full spin training.
I flew with
the test pilot when I got the glider, but he didn't
demonstrate
any full spins or spiral dives with recovery. I did
some
wing drops, but nothing like a full spiral or spin
like this.

I think my dad finally let go of the stick, and when
he did
it came back. I thought I did it slowly, but I might
have done it faster than I should have, because there
was a loud
snap and then the glider was rotating violently. I
popped
off the canopy and parachuted out.

*******fictional report ends*****

From this made up sequence of events, if I were getting
training
for such a glider, I'd want to focus on

1. positive exchange of controls, with the control
change echoed back
2. CRM agreement that whoever is on the stick handles
the emergency
(assuming both are fairly similarly qualified pilots).
3. reduction of distractions (radio, vario volume,
wrap-around ASI)
4. training in a glider certified for full spins that
is as alike
the glider I want to fly as possible.
5. enough acro and unusual attitude training to control
my rate of
control inputs during recovery, without panic.

Is this fictional report what actually happened? Probably
not,
but it is a fusion of my own experiences and what I
have read in
various fatal accident reports in various aircraft.

I don't believe just going up and doing some spin/spiral
recovery
training is specific enough. CRM issues and distractions
have
happened enough to fully 'trained' and 'experienced'
airline
and aerobatic pilots that I think human factors are
as important as
time on the stick feeling the pressures and hearing
the wind.

All right, kids, flame away! For the rest, if you
have specific
constructive insights that are on topic, I'd like to
hear them.
Thank you to Bert and Eric and Stefan for your useful
discussions.

As far as my wrap-around ASI confusion theory goes,
I can't ell if it is a good one or not. Clearly these
pilots
either didn't accurately know their airspeed, or they
DID, and just
misapplied corrective action. There is a subtle
difference there...

At 04:48 22 June 2005, Kilo Charlie wrote:

'Eric Greenwell' wrote in message
...
M B wrote:


Don't the controls feel differently at 30 knots and
100 knots? That should
be a good clue as you begin the spin recovery.


--
Change 'netto' to 'net' to email me directly

Eric Greenwell
Washington State


I am a partner in a Nimbus 3D. I have not had a lot
of time in it but have
flown aircraft of all kinds for 36 years including
hundreds of glider and
powered aerobatic hours. In order to get the Nimbus
to go beyond the green
arc it takes a very large amount of forward stick even
with the trim all the
way to the forward stop.....with flaps in -2. I absolutely
disagree that it
would be easy to let it get away from you and end up
in a spiral with the
exception of possibly entering it from a spin. The
spin enty on the other
hand is docile and easy to recover from. As has been
pointed out, if one is
clueless re incipient spins then the scenario in these
2 accidents might
easily unfold. Only education, planning and practice
will prevent similar
accidents.

Casey Lenox
KC
Phoenix



Mark J. Boyd


  #29  
Old June 22nd 05, 10:27 PM
Stefan
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M B wrote:

In my experience, I have seen and been a part of confusion
in
the cockpit. One pilot is saying one thing and the
other is
contradicting it. I've also had both pilots on the
controls at the same time, with opposite pressures
applied.


I'm more and more, well, surprized, what you have been experiencing
while flying. I've never seen, even less been part of such a thing.
Communicate before the flight, define the roles and adhere to it. Who
will do what? Who will fly in an emergency? Communicate during the
flight, and do so clearly.

And, you may ask, if the other pilot is doing something I don't like?
Well, if I don't trust the other pilot, I won't fly with him. If he
doesn't trust me, I don't want him to fly with me. Simple as that, very
basic CRM stuff. (It needn't be offensive when I say I don't like his
way of flying, because I'm not implying that he's a bad pilot, I'm just
saying our styles are incompatible.)

I'm surprized that, as it seems, you can become an instructor in the USA
without knowing such basic stuff.

Stefan
  #30  
Old June 22nd 05, 11:51 PM
Bob Kuykendall
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Earlier, Stefan wrote:

I'm more and more, well, surprized,
what you have been experiencing
while flying.


I have seen all of this and much, much worse. I don't say that it's
good or right, because obviously it's suboptimal. But it is what it is,
and everybody has to come to terms with it one way or another.

...And, you may ask, if the other pilot
is doing something I don't like?
Well, if I don't trust the other
pilot, I won't fly with him...


Hypothetical question: Suppose it's your _job_ to fly with this person?
Say, the person is your boss, and if you continue to decline then you
get fired with a bad fitness report that derails your flying career?

And, please, spare us the TS that such situations never happen, or that
they only happen in third-world countries. The records of the NTSB and
other national safety boards show that it happens with depressing
regularity.

I just finished reading an interesting book on the topic: "Darker Shade
of Blue," about rogue pilots in general and their effect on others. I
think it might go a bit over the top, since every pilot has a bit of
rogue to them, and sometimes it is that rogue element that carries the
day. But it is a valuable read regardless.

Furthermore, I'm pleased to see this thread directed more towards human
factors and the real world of soaring flight operations. I think it is
generally too easy to use "pilot error" as an excuse to not look deeper
into accidents and find their root causes. Peter Ladkin has a lot more
to say on that topic, and I generally agree with his assessments.

Following a slightly different tangent, as sailplanes become more
extreme in their complexity and dimension, the margins between early
adopters and the edges of the proven envelope will continue to shrink,
and will more often go negative in unexpected ways. Certification
doesn't _prove_ that a design is safe; it only demonstrates it under
carefully controlled conditions.

Thanks, and best regards to all

Bob K.

 




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