Ed Rasimus wrote:

On Mon, 12 Jan 2004 23:03:31 -0800, Mary Shafer
wrote:

Of course, the O'Hare DC-10 had a slat asymmetry, although that was an
asymmetric retraction of an extended slat. Subsequent simulator
studies showed that, even knowing the problem was asymmetric slats,
the airplane was too low to recover.

Mary

If we're talking about the same DC-10 that was lost at O'Hare about 20
years ago, the slat assymetry was caused by the engine and pylon
departing the wing, up and over and in the process taking a chunk of
leading edge with it.

The accident investigation and subsequent simulator trials
demonstrated fairly conclusively that the aircraft was recoverable,
however training to immediately pull up and reduce speed to Vmc was
incorrect.

But the thinking here is to gain maximum height and this will do
it in a normally configured a/c. That this one *wasn't* normally
configured couldn't be detected due to the 'slat asymmetry
warning' being unpowered because of failure of that busbar.

Had the slat warning worked then he 'wouldn't have pulled up to
Vmc'. So when the cojo followed instructions the port wing
stalled and took them in. They've since changed the dash one to
remove the requirement to climb at Vmc unless there's an urgent
need to.

This poor crew had everything against them, they lost the power
from that engine, they lost it's DC bus, they lost the slat plus
they lost the warning so even though the a/c was flown properly
they lost their lives because four major problems lined up
against them.

What was needed was the more high performance airplane
practice of "unload for control" in which you (counter-intuitively)
ease off the back pressure possibly all the way to zero G and let
airspeed build to a point where more G is available for the recovery.


But in the normal(?) case of a DC-10 engine fail there's lot's of
power from the other two so control isn't a problem and you'll
gain more height safety by climbing at Vmc...which was the
thinking then.

Apparently the chances of a wing engine failure plus an
asymmetric slat condition plus the left DC bus failure PLUS a
slat asym. warning failure was a pretty remote possibility.
--

-Gord.