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Re; Accelerated Stalls



Oops. I should have checked John's website refs. for this accident
before I replied (I would have but my browser decided to go south
just at that moment and wouldn't restart. I is working fine now, and
I have no idea what was wrong then or what is right now. But never
mind).

A few sentences from the abstract of the accident report:

"The PIC then received a weather briefing and was advised of moderate
icing conditions, turbulence, IFR flight precautions, and a cold
front in the area of the departure airport. The airplane was taxied
in rain to takeoff on runway 30. While taxiing, the PIC acknowledged
receiving information that the wind was from 280 degrees at 20
gusting 30 knots and that a departing Cessna 414 pilot reported
moderate low-level windshear of +/- 15 knots. The airplane then
departed on runway 30 towards a nearby thunderstorm and began a
gradual turn to an easterly heading. Witnesses described the
airplane's climb rate and speed as slow, and they observed the
airplane enter a roll and descent that was consistent with a stall.
Density altitude at the airport was 6,670 feet. The airplane's gross
weight was calculated to be 84 pounds over the maximum limit at the
time of the impact."

I had forgotten that the trip was taking place in the early spring,
which means it was still cold in Cheyenne, however, the conditions
they talked about in the weather report have the same net effect as
high temp.-that is, lowering the amount of weight the aircraft can
carry and still fly successfully. According to the report the density
altitude at takeoff was 6670 feet, and the aircraft was overloaded by
84 pounds. This doesn't sound like much, but if, as I suspect this
comparison is with the book value of the maximum T/O weight, then the
overload when raised to 6700 feet is substantially higher. And if
there was the possibility of icing in the area, the safety margin was
even further reduced.

The moments just before it crashed were described thus: "Witnesses
described the airplane's climb rate and speed as slow, and they
observed the airplane enter a roll and descent that was consistent
with a stall." In other words, when you are heavy, slow, and at high
altitude, but with the height above ground still small, stalls are a
distinct possibility.

My take on this is that the PIC *should* have vetoed the flight at
that time before they left the ground. The aircraft weight should
have been reduced considerably, most probably by off-loading some
fuel, and the flight delayed until the weather was better. They could
easily have simply made a short leg to a lower elevation airfield,
where they could have flown safely at the maximum takeoff weight.

Once the first mistake was made and they were airborne, the PIC
should have taken over the controls before the situation deteriorated
to catastrophic levels. Whether he ever did take over, I don't know.

But reading the abstract reminds me that the flight record they were
looking for had several restrictions-first there was a time limit-8
consecutive days (which I assume was imposed by the previous
record-holder). Any delays would jeopardize this limit. Second was
the family pressure to get this record, mentioned in my previous
post. Third was the fact that it was being done in a fishbowl of
publicity. Nobody wants to admit failure with the flashbulbs popping,
and I suspect nobody wanted to go home an have to face an angry
stage-mother who probably (if her statements after the event are any
indication) understood nothing of the nature of the situation at
Cheyenne.

So the situation was created where nobody wanted to admit that
conditions were marginal since that would put the time limit in
jeopardy, and once airborne, the PIC was reluctant to take control
since that would void the effort and require everybody to go back to
square one. It would appear that everyone was at least implicitly
willing to pay with their life for the attempt. The tragedy is that
it was so predictable. Even Scott had a better chance at getting back
from the South Pole.

Hugh