On Mon, 22 Sep 2008 06:10:03 -0700 (PDT), Amine
wrote:

Hey,

Some of you may have heard of Air Canada 143 [http://www.youtube.com/
watch?v=dfJIpA2gv1g] which ran out of fuel in mid air and had to make
an emergency descent at velocities way above the normal limits. The
pilot's makeshift technique was to engage a sideslip to decelerate the
aircraft (which by then had no flaps, and only minimal hydraulics).

Now I thought that sideslips (and crabs--whatever the difference
between the two is...) were only to be used to handle crosswinds. I
didn't read anywhere that they could be used to bleed excessive speed,
although it makes sense from an aerodynamics perspective. Anyone out
there used sideslips for anything other than crosswind approaches?

PS: I have read about many cases of jetliners that had to make
emergency descents at abnormally high speeds, but the AC143 seems the
only one to have used the sideslip.

all the time to increase the descent angle. not because of bad
piloting mind you.

I was given clearance to land at Parafield once when I came over to
refuel. the clearance was absurd since I was above short base at
1500ft still approaching the circuit but a clearance to land it was
and it was convenient. I side slipped off nearly 1500ft and made it
bang on the numbers. not bang as in splat but 'bang on' as in
precisely at the position (australian idiom)

Sideslips are a very useful tool because they allow you to
substantially increase the drag, which makes you descent like a
plumbers toolbag, but doesnt change the forward speed. so you have no
increased risk of stalling as you wash off the height.

The Gimli glider pilot used the technique for all the right reasons.
Stealth Pilot