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Subject: Re: When is turbulence "extreme"?
From: Shilling)
Date: Aug 09 1996

In <pdb1.839539333@Isis.MsState.Edu> pdb1@Ra.MsState.Edu (Philip D
Bridges) writes: 

> (patterson,george r) writes:
>>The definition of turbulence is supposed to be fairly simple.
>>    1. Light turbulence sort of kicks the plane around but at no
>>       time is the aircraft out of control.
>>    2. In moderate turbulence the aircraft makes uncommanded changes
>>       in attitude and is occasionally out of control.
>>    3. In severe turbulence the aircraft is frequently out of control. (Craig Welch) writes:
>}So to my question. When would a commercial jet pilot consider
>}turbulence "extreme"?

<> Bill wrote:
>    When 100% Control Deflection does not stop the roll, pitch, or
>yaw.  Same as for any other aircraft.

I experience extreme turbulence once.  It happened while flying a
C-47 on a trip across the Himalayan mountains.  I was east bound
cruising at 20,000 feet.  My destination was an airfield on the
east side of an 18,500 foot mountain.  As I passed over the 18,5
mountain I dropped my gear and started descending in order to land
at the airfield whose elevation was 8,000 feet.  

I had been flying in a 60 mph tail-wind, and without thinking, as
I descended on the lee side of the mountain, I became embroiled in
the roll wave coming off of the mountain.  I had descended 2,000
feet, about 500 feet below crest of the mountain, when all hell
broke lose.  Turbulence, the like of which I have never encountered
before or since.  Even with the gear down, and power completely
off, pitch angle went from 60 degrees above the horizon to 60
degrees below.  Airspeed went from 60 mpg to 250 mph.  Aircraft
roll was just as great.  With great effort, I managed to turn to a
southern heading, and eventually got out of the roll wave coming
off the mountain peak.  

After that I was able to proceed to my intended destination without
further incident. Finally landed at Liaking airfield in China. 

Erik Shilling
Erik Shilling		Author; Destiny: A Flying Tiger's 
Flight Leader              Rendezvous With Fate.
3rd Squadron AVG
Flying Tigers

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