On 28 Feb 2005 18:19:31 -0800, "Bravo8500"
wrote:

This is just the way wind shear works. Yes, it's an extreme example,
but I've stalled in level flight at Va on a beautiful clear day.

The first clue to extreme shear conditions is the large change in
direction in a relatively small change in altitude. If you cruise at
165 into a 40 knot head wind and abruptly enter a 40 knot tail wind
you are going to lose 80 knots. If you have the altitude it will
eventually end up at the original cruise. OTOH if you went from a 40
knot tail wind to a 40 knot head wind abruptly, can you imagine what
that would do to the plane. You not only would have some extreme
turbulence, but would temporarily hit close to 240 knots which is well
above Vne.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

I thought this was interesting so I'll share it. I hit some unusual
windshear I suppose last night going into St. Simmon's Island, GA
(BQK) in an A36 Bonanza. Here we were, me flying and the non-pilot
owner (my brother-in-law) in the right seat cruising at 3000 over the
top of a broken layer about 25 south of the localizer to runway 7,
about 9:30 EST. We were in moderate to occasionally severe turbulance
and I had been warned by the FSS briefer about a windshear at 1000 agl
- I think it was the fact that there was a 180 degree diff in wind
direction between the surface and 1000 agl that was causing it. Oh
yeah, a big fat low pressure was sitting right on top of BQK, more or
less, as I could determine from the duats graphical current analysis in
the motel room an hour later. The pressure had been dropping since
Atlanta and the altimeter was down to 29.68 I believe. Anyway, here we
are in flat out cruise, I look up and notice I'm only indicating 140
or so when I should see 165, and dropping a couple of knots per second.
As the airspeed goes through 110, I bring in full RPM and manifold and
we continue to lose airspeed down to 80 knots. I'm wondering what the
heck is going on, we're now in a climb attitude and get one blip of
the stall warning. By this time I've disengaged the ap and now am
allowing the airplane to drop to maintain around 80. I'm just about
to call ATC when we start picking up airspeed, slowly. Man, that was
weird.