Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Colorado Spgs, Colorado 80901
Sunday, March 3, 1991 9:44 MST
NTSB Narrative Summary Released at Completion of Accident
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.
NTSB Probable Cause Narrative
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.
Event Information
| Type of Event | Accident |
| Event Date | 3/3/1991 |
| Event Day of the Week | Sunday |
| Time of Event | 944 |
| Event Time Zone | Mountain Standard Time |
| Event City | COLORADO SPGS |
| Event State | COLORADO |
| Event Country | -- |
| Zipcode of the event site | 80901 |
| Event Date Year | 1991 |
| Event Date Month | 3 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | |
| Event Location Longitude | |
| Event Location Airport | |
| Event Location Nearest Airport ID | |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | 0 |
| Degrees magnetic from airport | 0 |
| Airport Elevation | -- |
| Weather Briefing Completeness | Full |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 950 Mountain Standard Time |
| Direction of event from weather observation facility (degrees) | 360 |
| Weather Observation Facility ID | COS |
| Elevation of weather observation facility | 6172 |
| Distance of event from weather observation facility (units?) | 3 |
| Time Zone of the weather observation | MST |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 0 |
| Lowest Non-Ceiling Height | 0 |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | 0 |
| Visibility Runway Visual Value (Statute Miles) | 0 |
| Visibility (Statute Miles) | 99 |
| Air Temperature at event time (in degrees celsius) | 9 |
| Dew Point at event time (in degress fahrenheit) | -13 |
| Wind Direction (degrees magnetic) | 330 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 23 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Unknown |
| Wind Gust (knots) | 33 |
| Altimeter Setting at event time (in. Hg) | 30 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | Fatal |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | 25 |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 25 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 154 |
| NTSB Notification Source | -- |
| NTSB Notification Date | -- |
| NTSB Notification Time | 0 |
| Fiche Number and/or location -used to find docket information | 43000 |
| Date of most recent change to record | Dec 12 2000 9:31AM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N999UA |
| NTSB Number | DCA91MA023 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 121: Air Carrier |
| Type of Flight Plan filed | IFR |
| Flight plan Was Activated? | -- |
| Damage | Destroyed |
| Aircraft Fire | Ground |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | BOEING |
| Aircraft Model | 737-291 |
| Aircraft Series Identifier | 737-291 |
| Aircraft Serial Number | 22742 |
| Certified Max Gross Weight | 110000 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 105 |
| Number of Engines | 2 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Continuous Airworthiness |
| Date of Last Inspection | May 27 1990 12:00AM |
| Airframe hours since last inspection | 2046 |
| Airframe Hours | 26050 |
| ELT Installed | No |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | UNITED AIRLINES |
| Aircraft Owner Street Address | |
| Aircraft Owner City | CHICAGO |
| Aircraft Owner State | IL |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 60607 |
| Operator is an individual? | -- |
| Operator Name | UNITED AIRLINES |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | |
| Operator City | CHICAGO |
| Operator State | IL |
| Operator Country | |
| Operator Zip code | 60607 |
| Operator Code | UALA |
| Owner has at least one certificate | Yes - certificate holder |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | Unknown |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | Scheduled |
| Indicates Domestic or International Flight | Domestic |
| Operator carrying Pax/Cargo/Mail | Passenger Only |
| Type of Flying (Per_Bus / Primary) | Unknown |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | No |
| Departure Airport Code | DEN |
| Departure City | DENVER |
| Departure State | CO |
| Departure Country | |
| Departure Time | 923 |
| Departure Time Zone | MST |
| Destination Same as Local Flt | crash at destination city |
| Destination Airport Code | |
| Destination City | |
| Destination State | |
| Destination Country | |
| Specific Phase of Flight | Approach |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jan 2 2001 10:30AM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 0 |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |