Date: 01 Dec 96 04:08:55
From: wsherr6080@aol.com
Organization: AOL http://www.aol.com
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RE: Request for more information on the Northwest Airlines Boeing 720B
accident near Miami, FL on Apri 12, 1963. The aircraft pitched up as a
result of a strong updraft and the crew reacted by trimming both the
elevator and the horizontal stabiliser to the full nose-down position as
well as applying a strong forward pitch control force on the control
column. The aircraft was upset into a vertical dive from 19,000 feet, the
crew had about 35 seconds to effect a recovery which was impossible, and
the aircraft came apart in the air!
In a weather induced "pitch-up" there is little or no increase in aircraft
load factor due to the vertical component of the relative wind. In the
Colorado Springs United Airlines Boeing 737 accident investigators ignored
the indication of a nose up indication because it was not accompanied by
an increase in aircraft load factor. Eye witnesses claimed they saw the
nose rise just before the instantaneous transition to the vertical dive.
There is the possibility that in the completely smooth air that existed at
the time wake turbulence from other aircraft in the area (I understand
there were 3 or 4) could be a factor and that an upset occurred prior to
the explosion and possibily as a result of the radical mannuever. (wake
turbulence can persist for 45 minutes or more in completely smooth air,
as I have experienced at high altitude and again at a low altitude.)
If pilots are looking at there instruments they will react regardless of
whether it is in visual flight conditions! e.g. Colorado Springs,
Pittsburgh, Charlotte
