When a stall/spin happens or nearly happens, it is only if the pilot has the
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" wrote in
message ...

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