Another stall spin

On Monday, September 3, 2012 11:44:04 AM UTC-4, Dan Marotta wrote:
If I thought I was going to die every time I flew, I wouldn't fly. The problem, as I see it, with these low altitude stall/spin accidents stems from the desire to get home rather than landing out. Back in the '70s the USAF called it "Get-Home-itis" and warned that it was a good way to get killed. Pilots need to make the decision to terminate a flight before there is no option other than landing in an unlandable place or trying to make a low save a mile from home just to avoid the inconvenience of a retrieve. Long ago I made the committment to never be outside of gliding distance of a suitable landing area. I also carry the phone numbers of people who have told me that they will come to get me if I land out. I always know where I will land if I don't get that next thermal so there's no problem if I don't get it and there are never any attempts to thermal at 300' AGL. Of my conservatism causes me to rarely get more than 500Km in a day, but I can *live* with that. "BobW" wrote in message ... On 9/2/2012 3:45 AM, Chris Rollings wrote: Most of a Very Excellent original post snipped... ...The next remark was very revealing (remember this was only about 2 minutes after he had spun in), "I can't understand what happened, there must have been something wrong with the elevator, I kept pulling back on the stick but the nose wouldn't come up." I wonder...: 1) what percentage of glider pilots think of the stick (as in elevator/pitch) as a "nose up/down control"? 2) what percentage of glider pilots think of the stick (as in elevator/pitch) as a "speed control"? I believe 2) is the better/safer manner of thinking about it. It will ALWAYS result in the correct action being taken "if the elevator quits working" at pattern speeds. (If we've any anal aerobatic mavens, please don't muddy the picture; this thread IS about pattern departures. :-)) - - - - - - He had been trained, about 8 years earlier, in a regime which did include spinning and recovery in pre-solo training, but there was no requirement for anything like a BFR or annual check so long as he remained current. In all probability he had not seen a spin from inside the cockpit for a number of years. Little wonder that he did not recognise it instantly. I'm unconvinced recurrent training is "the complete ticket". I believe that how one fundamentally thinks (in this case, about pattern risks) is no less crucial...perhaps even MORE crucial. I also wonder how many glider pilots actively think when in the pattern "If I don't get everything as I intend/need-to, I could DIE during THIS pattern!"? I believe having such a thought in one's active awareness predisposes the mind toward awareness that pattern departures *can* occur, and if "instant" recognition/corrective action (reduction of AOA) does not occur, death is likely to soon follow. With such a thought in mind, it arguably should not matter how long ago one's recurrent training involving pattern "departure gotcha scenarios" occurred. - - - - - - ...Even pilots trained under the UK system (which does include spinning and recovery practice as part of the pre and post solo training), can't be expected to recognise an unintentional spin that quickly if they haven't seen and practiced one for months or years. ...The only thing that will work is frequent practice and only instructors who are teaching spinning regularly are really likely to get enough. To indulge in playful quibbling...is Chris R. here suggesting that only instructors be allowed to fly patterns, since "...only instructors who are teaching spinning regularly are really likely to get enough (unintentional spin entry practice to quickly recognize pattern departures)"? OK, I know he isn't, but to quibble with his point about "practice being necessary/crucial" to rapidly recognizing incipient pattern departures, I'm reasonably convinced that how a person thinks, matters...a lot!!! If a person is mentally primed for the *possibility* of incipient departure in his or her landing pattern, then not only is s/he less likely to inadvertently play in that corner of the sandbox, but s/he will also be mentally primed to rapidly/correctly react with the stick. - - - - - - Practice is great (whether governmentally mandated or self-motivated). Just don't fall into the mental trap of "*temporarily* (i.e. "because you're practicing") opening your mind" to practice and its lessons, when it should *always* be open to death-inducing possibilities. Bob - heightened awareness pattern flyer - W.

Two of the most recent were where all the pilot had to do was land on the airport so I think your point is not applicable to them. That said, knowing they could land if they fell out may have made them more comfortable trying to make the low saves.
I do agree that get home itis can be a strong motivator toward dangerous behavior.
UH

What is the lowest altitude at which you could recover from a spin, and still have enough safety margin to land? I would not thermal below this altitude, but that is just me.

When I have just stalled a wing, I'm just above the critical AoA and my win
g produces hardly any lift, so my AoA will increase further. But when I det
ect this early enough I might be able to get below the critical AoA by just
moving the flaps forward.

Minor minor detail, but...
You mention the critical AoA as if it is 1 fixed value.
In subsonic airflow there is hysteresis around the stall, so the AoA needs to be a little bit lower than where it starts to stall in order to un-stall.
It is only a few degrees, but it is something which consistently shows in wind tunnel polars.
Nevertheless, and important detail if one were to come up with an automatic flap-un-staller device :-)

Roel

On Monday, September 3, 2012 10:48:44 AM UTC-7, hlt wrote:
Instructors are normally quite recent in spin recovery with the training glider. But the stall, spin and recovery characteristics of widely used trainers is quite different from stall, spin and recovery characteristics of the race ships we instructors use for our xc. Most of the high AoA things you can to with a K21 you can't do with one of the race-ships.

Just looking at the statistics in the US from the last couple of years alone, it shows that the majority of fatalities were CFIG, commercial pilots, FAA examiners, in other words, those who likely not only have spin training, but also provided spin training. We just lost another one. What gives? Go figure.

Ramy

Such a device exists -- it is located just behind the pilots eyes
and between his ears. Fed automatically from sensors located
around the body.

As glider pilots we regularly, by choice, fly in conditions
designed to induce a spin. I.E Turning often tightly, close to the
stall speed in rising air.

Surely we owe it to our families and friend to learn to recognise
this situation, the symptoms and the information given out by
the aircraft we fly through our senses, AND DO something to
stop it happening "fly a little faster"

As instructors we need to hammer the message home...

Just my two cents worth

Dave

At 05:02 04 September 2012, Roel Baardman wrote:
When I have just stalled a wing, I'm just above the critical
AoA and my
win
g produces hardly any lift, so my AoA will increase further.
But when I
det
ect this early enough I might be able to get below the critical
AoA by
just
moving the flaps forward.

Minor minor detail, but...
You mention the critical AoA as if it is 1 fixed value.
In subsonic airflow there is hysteresis around the stall, so the
AoA needs
to be a little bit lower than where it starts to stall in order to
un-stall.
It is only a few degrees, but it is something which consistently
shows in
wind tunnel polars.
Nevertheless, and important detail if one were to come up with
an automatic
flap-un-staller device :-)

Roel

It's easy enough to practice low (within a few wing spans), slow, high bank angle turns in a power plane like a Super Cub or Husky. Not so many opportunities in a glider. To the uninitiated, there's a tendency to skid a turn when low, as some pilots try to minimize bank angle - too much bottom rudder, not enough aileron. Not a good situation to be.

On Sep 1, 8:43*pm, wrote:
Not unreasonable to think that hills/mtns, buildings, tree lines and obstacles present a similar phenomenon from surface winds.

I'm catching up on this thread; but in case no one has mentioned it
yet: Surface objects (such as buildings, trees, small hills, etc) can
create turbulence downwind to a distance of 10-20 times their height.
When I flew R/C models this was *very* noticeable!

For example, a small stand of trees 100 feet high can cause turbulence
1/4 to 1/2 mile downwind of the trees. That seems like quite a ways
off (horizontally) if you're down low and scratching, so you may not
think about such objects. But they can have a profound impact on the
air you run into when you're making a save. And as John Sullivan
noted, that air is already quite "confused"!

--Noel

On Sep 4, 10:34*am, bumper wrote:
It's easy enough to practice low (within a few wing spans), slow, high bank angle turns in a power plane like a Super Cub or Husky. Not so many opportunities in a glider. To the uninitiated, there's a tendency to skid a turn when low, as some pilots try to minimize bank angle - too much bottom rudder, not enough aileron. Not a good situation to be.

Yes, one thing to point out is that a lot of training spins emphasize
a lot of back-stick *plus* a punch on the rudder to initiate the
spin. But IMHO this isn't how spins develop in the real world. I
believe that many spins develop as the aircraft's situation degrades
over a couple of seconds (airspeed bleeds off, or back-stick/rudder is
slowly added in by the pilot without realizing they're "creeping" on
the controls).

Another item for thought: Using trim on an aircraft is great (I am
constantly re-trimming my aircraft). BUT if you trim the aircraft for
flight at a slow speed (say an approach-speed that's a little too
slow), the trim-spring is what is "pulling back" on the stick. YOU
will not feel yourself pulling on the stick. Yet the aircraft may be
dangerously close to a stall/spin. And once it starts to develop
you'll have to PUSH *against* the trim spring in order to un-stall the
wing! Simply "relaxing the back-pressure" will not break the stall or
stop the spin. This goes against a lot of the muscle-memory we learn
when we train in gliders and perform training stalls & spins, so
pilots are not likely (IMHO) to take the full corrective action.

Lastly, think about wind gradient and headwind/tailwind components...
Let's say we're making a landing pattern (and this could be
particularly bad in an off-field situation). There's a tailwind on
downwind so the ground rushes past and we try to slow down (perhaps
subconsciously). Then we turn base/final and while we get a bit of
the headwind, we also have to remember low level wind gradients mean
that as we descent down close to the ground that headwind goes away.
So we have pulled the stick back (from trying to "slow down" on
downwind) AND we lose lift as the headwind decreases. Stall, anyone?
And possibly a spin, if the wind gradient kicks in during the base-to-
final turn. Think about the typical base-to-final spin accident -
they tend to happen when people are low and not yet on final, right?
So isn't it possible that its not just them "skidding" the turn, but
also possibly aggravated by the wind gradient? How many instructors
discuss the wind gradient with their students? How many discuss it in
terms of a low base-to-final turn?

--Noel
(CFIG-in-training)

I prefer to move the trim full forward before entering the pattern. The
back pressure required has not been a problem with the various gliders I've
flown. If I get distracted for some reason I hopefully will be flying
faster than required, rather than slower. I too find it easier to control
air speed by varying the back pressure. If the glider is trimmed for
approach speed and there is a loss of headwind due to ground friction, the
forward pressure required to maintain airspeed feels unnatural to me.

At 00:02 05 September 2012, noel.wade wrote:
On Sep 4, 10:34=A0am, bumper wrote:
It's easy enough to practice low (within a few wing spans), slow, high
ba=
nk angle turns in a power plane like a Super Cub or Husky. Not so many
oppo=
rtunities in a glider. To the uninitiated, there's a tendency to skid a
tur=
n when low, as some pilots try to minimize bank angle - too much bottom
rud=
der, not enough aileron. Not a good situation to be.

Yes, one thing to point out is that a lot of training spins emphasize
a lot of back-stick *plus* a punch on the rudder to initiate the
spin. But IMHO this isn't how spins develop in the real world. I
believe that many spins develop as the aircraft's situation degrades
over a couple of seconds (airspeed bleeds off, or back-stick/rudder is
slowly added in by the pilot without realizing they're "creeping" on
the controls).

Another item for thought: Using trim on an aircraft is great (I am
constantly re-trimming my aircraft). BUT if you trim the aircraft for
flight at a slow speed (say an approach-speed that's a little too
slow), the trim-spring is what is "pulling back" on the stick. YOU
will not feel yourself pulling on the stick. Yet the aircraft may be
dangerously close to a stall/spin. And once it starts to develop
you'll have to PUSH *against* the trim spring in order to un-stall the
wing! Simply "relaxing the back-pressure" will not break the stall or
stop the spin. This goes against a lot of the muscle-memory we learn
when we train in gliders and perform training stalls & spins, so
pilots are not likely (IMHO) to take the full corrective action.

Lastly, think about wind gradient and headwind/tailwind components...
Let's say we're making a landing pattern (and this could be
particularly bad in an off-field situation). There's a tailwind on
downwind so the ground rushes past and we try to slow down (perhaps
subconsciously). Then we turn base/final and while we get a bit of
the headwind, we also have to remember low level wind gradients mean
that as we descent down close to the ground that headwind goes away.
So we have pulled the stick back (from trying to "slow down" on
downwind) AND we lose lift as the headwind decreases. Stall, anyone?
And possibly a spin, if the wind gradient kicks in during the base-to-
final turn. Think about the typical base-to-final spin accident -
they tend to happen when people are low and not yet on final, right?
So isn't it possible that its not just them "skidding" the turn, but
also possibly aggravated by the wind gradient? How many instructors
discuss the wind gradient with their students? How many discuss it in
terms of a low base-to-final turn?

--Noel
(CFIG-in-training)

Good point on wind gradient. The aircraft here was an ASW19? That was my first ship.

My condolences to family,
Darren