United Airlines Boeing 747 Turbulence Encounter

Date:         11 Jan 98 03:24:56 
From:         wsherr6080@aol.com (WSherr6080)
Organization: AOL http://www.aol.com
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The recent United Airlines Boeing 747 severe turbulence encounterserves as
irrefutable evidence of the weather induced aircraft "pitch-up" in an updraft.
(A phenomenon of the swept wing aircraft design), and the resultant pilot's
reaction to this instantaneous attitude transition.

The simulation, on television, of the United 747 aircraft transitions during
the turbulence encounter shows a definite aircraft "pitch-up" to a nose high
attitude as a result of a severe updraft. The Flight Data Recorder FDR
inddicated a positive two "G" reading.

The pilot's instinctive and involuntary reaction to this instantaneous nose up
attitude change is to return to level flight asap.  The application of a strong
forward pitch control input results in a high negative "G" force which pitches
any loose objects up to the ceiling.  (The classic example of a weather induced
"pitch-up" and a resultant pilot induced "upset" accident was the Northwest
Airlines Boeing 720B fatal accident near Miami, Fl in 1963.  (The Boeing 720B
is 7 feet shorter than the 707)  The Northwest crew in reaction to a weather
induced "pitch-up" trimmed both the horizontal stabilizer and the elevators
full nose down and also applied a strong forward pitch contro input that upset
the aircraft into a vertical dive. The aircraft came apart in the air.

If the United 747 aircraft had actually fallen from a level flight attitude all
the passengers would have been subjected to the same powerful "G" forces. The
fact is the most severe injuries were inflicted on the passengers in the rear
of the aircraft. The "G" forces increase towards the rear of the aircraft.
(Longer moment arm)

Until the aviation industry recognizes this "pitch-up" phenomenon of a swept
wing aircraft design, and initiates a pilot training program to counter the
instinctive and involuntary reaction of a pilot to these sudden, uncommanded
aircraft attitude transitions, these incidents and accidents will continue to
occur.

wsherif1@san.rr.com