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.