It was shortly before noon on March 3,
1991 and United flight 585 was
completing it's service from Denver to
Colorado Springs. There were only 25
people on board the short 20 minute
flight. With Captain Green and First
Officer Eidson on the flight deck, the
737 departed into clear skies, with
visibility at Colorado Springs reported
at 100 miles, but winds were gusting up
to 20kts. The aircraft had just
completed it's turn onto the final
approach for runway 35 and was
descending through 1,000ft. Suddenly,
the aircraft rolled out of control to
the right, passing through 90 degrees.
The plane continued to roll until it was
inverted, plunging nose-first into the
ground. The impact was near vertical,
leaving a 10ft deep crater and
scattering wreckage in an area of only a
few hundred feet in diameter. All aboard
the aircraft were killed.
......Investigators found no anomalies
in the hydraulic system which could had
led to loss of flight control. There
were small anomalies in the aircraft's
rudder control system, but investigators
determined that they were not of such a
magnitude to be able to cause any kind
of control loss. The investigation then
turned to meteorological conditions.
Because there was no heavy traffic
ahead, it was not believed that 585
encountered wake turbulence like that
which was seen in the crash of Delta
N3305L. Though the skies were clear,
winds were gusting at the time of the
accident.
Because Colorado Springs Municipal
Airport is surrounded by mountains,
these strong winds were conducive to the
formation of rotors. Because there were
no clouds at the time, there was no
visual indication of rotors. However,
some ground witnesses did indicate that
they saw isolated formations which
supported the existence of a rotor. The
FDR recorded several vertical and
lateral gusts, but none were of the
magnitude which was believed necessary
to render the aircraft uncontrollable.
An aircraft which had
landed some minutes before 585 reported
encountering slight windshear, but
nothing that would indicate and
potential problems for the crew. Because
of this accident, several encounters
with uncommanded rudder movements by
other flight crews came to light. Though
investigators examined the systems both
on in-service aircraft and Boeing
factory design, no obvious answers could
be found. The aircraft which was
destroyed in this accident had two
reports of uncommanded rudder movement
in just the week prior to the accident.
The crash slowly faded out of the
spotlight until a nearly identical
accident, USAir 427, occurred some three
years later. As of this time, both
investigations are still open. Eidson
had the sad distinction of being the
first women airline pilot killed,
ironically on a flight that she was not
scheduled to make, but offered to take
to make some extra money.
