- Date
- March 3, 1991, 09:44 local (16:44 UTC)
- Place
- Colorado Spgs, CO
- Injuries
- 25 fatal
- Damage
- Destroyed
- Phase of flight
- Approach
- Aircraft
- N999UABoeing 737-291
- Weather
- Visual (VMC) · Day
- Status
- Completed · report August 5, 1993
- Report
- Board-adopted at Board Meeting
- Investigation class
- Class 1
- NTSB office
- Major Investigations Division
- Safety recommendations
- Yes
- FAA report
- 19910303003669A
- Case key
- 15948
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
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.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
Executive Summary
On March 3, 1991, a United Airlines (UAL) 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 (VMC) prevailed at the time, and the flight was on an instrument flight rules (IFR) flight plan. Numerous witnesses reported that shortly after completing its turn onto the final approach course to runway 35 at Colorado Springs Municipal Airport (COS), 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.
Aircraft
- Registration
- N999UA
- Reported as
- Boeing 737-291
- Category
- Airplane
- Serial number
- 22742
- Airframe hours
- 26,050
- Engine
- P&W JT8D-17, 15,000 lbs thrust, turbo jet
- Damage
- Destroyed
- Fire
- On-Ground
- Flight
- Part 121
- Operator
- United Airlines
- Registered owner
- United Airlines
- Airworthiness certificate
- Standard, Transport
- Last inspection
- Continuous airworthiness · May 27, 1990 · 2,046 hours before
- Departed
- DEN · Denver, CO
- Flight plan
- IFR
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 52
- Certificates
- Commercial, Flight engineer, Airline transport
- Airplane ratings
- Multi-engine land, Single-engine land
- Instrument ratings
- Airplane
- Medical
- Class 1, Valid Medical--w/ waivers/lim
- Seat
- Left
- Toxicology
- Performed
- Flight hours
- 9,902 total · 1,732 in this make and model
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 330° at 23 knots, gusting 33
- Visibility
- 99 statute miles
- Lowest ceiling
- None
- Temperature
- 48 °F, dew point 9 °F
- Altimeter
- 30.00 inHg
- Observed at
- COS, 3 nm away
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.