Investigation Summary
The emergency began when the right main landing gear retract cylinder assembly failed due to corrosion, causing the gear to free-fall. This rapid extension damaged a microswitch, preventing the cockpit 'down and locked' indicator light from illuminating. Captain McBroom elected to hold at 5,000 feet to diagnose the problem and prepare the cabin for a potential emergency landing. For approximately 54 minutes, the aircraft remained in a high-drag configuration with gear down and 15 degrees of flaps, significantly increasing fuel burn. The NTSB investigation highlighted a critical breakdown in cockpit communication: while the flight engineer and first officer were aware of the low fuel state and attempted to convey the urgency, they were not assertive enough to override the captain's preoccupation with the gear. The captain, conversely, failed to integrate their warnings into his decision-making process. The aircraft eventually suffered a total loss of power as all four engines flamed out sequentially, leading to a crash-landing in a wooded area approximately six nautical miles southeast of the airport.
Final Conclusions
The NTSB determined the probable cause was the captain's failure to properly monitor the aircraft's fuel state and respond to crewmember advisories. A contributing factor was the failure of the other two flight crewmembers to fully comprehend the criticality of the fuel state or successfully communicate their concerns to the captain. The investigation concluded that the crew's attention was directed almost entirely toward the landing gear malfunction, leading to a total loss of situational awareness regarding their remaining flight time.
Video Analysis
United 173: The Wrong Problem, A Real Tragedy — A detailed look at the McDonnell Douglas DC-8 that ran out of fuel near Portland, Oregon, and how the tragedy led to the birth of Crew Resource Management (CRM).
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Captain
Malburn McBroom
First Officer
Roderick Beebe
Flight Engineer
Forrest Mendenhall
Systems & Failure Modes
Landing Gear Retract Cylinder
A mechanical failure due to corrosion caused the right main gear to free-fall, damaging the indicator microswitch.
Fuel Quantity Indicators
The DC-8 featured both engine fuel flow and tank quantity gauges; however, the crew failed to relate these readings to their remaining endurance.
Crew Resource Management (CRM)
This accident led to the development of CRM, a training system designed to improve communication and collaborative decision-making in the cockpit.
Interesting Facts
- 01The aircraft was a stretched DC-8-61 delivered new to United Airlines in May 1968.
- 02The crash resulted in 10 fatalities: 8 passengers, the flight engineer, and one flight attendant.
- 03The wreckage path was approximately 1,554 feet long and 130 feet wide.
- 04There was no post-crash fire because the aircraft had completely exhausted its fuel.
- 05The captain, Malburn McBroom, had over 27,600 hours of flight experience.
Safety Actions & Advisories
Implementation of CRM
United Airlines instituted the industry's first Crew Resource Management program for pilots in 1981 to address human error and poor crew coordination.
FAA Operations Alert Bulletin
Source ↗The NTSB recommended that the FAA ensure crew training stresses differences in fuel-quantity measuring instruments to prevent misinterpretation.