"Martin Hellman" wrote in message
om...
Stewart Kissel wrote in
message ...

'A terrible day at Val Air today... not for me, but
Joe Dulin... a recently transplanted Turf pilot. Joe
has been flying tourists for ValAir and today stalled?spun?
in in the L-13 with a passenger on the end of the runway
after a low pass and steep pull-up.

Low passes with steep pull-ups are a blast, but as this accident
shows, entail risk. Since he was doing rides, the pilot involved was
probably highly experienced and done these many times before with no
problems.

When I was doing my motor glider transition at Livermore, the guy who
then owned the operation told me that there are certain maneuvers he
loves doing (high speed low passes among them), but doesn't do
frequently because of their danger.

One of the biggest problems with actions like low passes and tree-top
ridge flying is that you might be able to do them safely 9,999 times
out of 10,000 (or something on that order), creating a feeling of
complacency. But if you do them 1,000 times during your flying career,
you'll have roughly a 10% of an accident -- possibly fatal.

Peter Masak's recent accident that Tom Knauff wrote about in his email
newsletter sounds like it occurred during close in ridge flying. And,
when I did a Google search to try and learn more about that accident
(no luck there), what I did come up with was a 1994 post in which
Peter commented on Klaus Holighaus' fatal crash -- which also sounded
like a ridge accident.

All this is making my Livermore friend's decision sound very
reasonable. It's OK to take a chance -- but not too often.

Martin

A low pass with a pull-up into a downwind is a great example of risk
management. A pilot has little margin for less than perfect flying. The
danger is greatest when they are performed on the spur of the moment in
response to a burst of exuberance yet they can be done safely with planning.

My approach is as methodical as possible. I will perform chandelles at a
safe altitude until I know exactly what a particular glider is capable of.
I note the altitude gain at the 180 degree point and any variability in that
gain. I will deliberately fly the maneuver with the yaw string out of
center to see how forgiving the glider is to sloppy flying. Only when I am
certain that I know all of the gliders behaviors related to chandelles will
I even consider doing low pass. Then I look at the particular runway and
the options to abandon the maneuver with a landing in another area than
planned. (Dry lakes are great for practicing this.)

Val air, as the name suggests, is a single runway in a beautiful, narrow,
steep sided high mountain valley. A pilot flying a low pass would have no
horizon for reference since his view would be the rocky sides of the canyon.
There are no safe landing options other than the runway. The elevation is
far higher than that at Turf so the higher TAS would create the illusion
that the glider's IAS was higher than it really was. Finally, the L-13's
ability to gain height in a zoom is less than the Grob 103's flown at Turf.
Unlike the Grobs, it will spin with only modest provocation. In short, the
margins at Val Air were far less than at Turf. It looks like the mountains
bit yet another pilot.

Bill Daniels