Date & Time:
Mar 3, 1991 at 0944 LT
Type of aircraft:
Boeing 737-200
Operator:
Registration:
N999UA
Flight Phase:
Landing (descent or approach)
Flight Type:
Scheduled Revenue Flight
Survivors:
No
Schedule:
Peoria – Moline – Denver – Colorado Springs
MSN:
22742
YOM:
1982
Flight number:
UA585
Country:
United States of America
Region:
North America
Crew on board:
5
Crew fatalities:
5
Pax on board:
20
Pax fatalities:
20
Other fatalities:
0
Total fatalities:
25
Captain / Total hours on type:
1732
Copilot / Total hours on type:
1077
Aircraft flight hours:
26050
Aircraft flight cycles:
19734
Circumstances:
On March 3, 1991, a United Airlines Boeing 737, registration number N999UA, operating as flight 585, was on a scheduled passenger flight from Denver, Colorado, to Colorado Springs, Colorado. Visual meteorological conditions prevailed at the time, and the flight was on an instrument flight rules flight plan. Numerous witnesses reported that shortly after completing its turn onto the final approach course to runway 35 at Colorado Springs Municipal Airport, about 0944 mountain standard time, the airplane rolled steadily to the right and pitched nose down until it reached a nearly vertical attitude before hitting the ground in an area known as Widefield Park. The airplane was destroyed, and the 2 flight crewmembers, 3 flight attendants, and 20 passengers aboard were fatally injured.
Probable cause:
A loss of control of the airplane resulting from the movement of the rudder surface to its blowdown limit. The rudder surface most likely deflected in a direction opposite to that commanded by the pilots as a result of a jam of the main rudder power control unit servo valve secondary slide to the servo valve housing offset from its neutral position and overtravel of the primary slide.
Final Report:
N999UA.pdf3.84 MB
