Incident Overview
On July 11, 1961, at 1136 Mountain Standard Time, a United Air Lines Douglas DC-8 aircraft (registration N8040U) crashed during its landing roll at Stapleton Airfield in Denver, Colorado. None of the 122 occupants on board sustained severe injuries directly from the impact; however, 16 passengers died from carbon monoxide poisoning as a result of the aircraft fire. Additionally, an elderly female passenger broke both ankles while evacuating the aircraft and later died from shock. The driver of a panel truck that was struck by the aircraft after it left the runway also suffered fatal injuries.
Hydraulic Difficulties
After departing from Omaha, Nebraska, the flight crew experienced hydraulic difficulties. They continued the flight to Denver using procedures outlined in the flight manual for abnormal hydraulic situations. Upon arrival in the Denver area, preparations were made for landing. The ejectors were extended hydraulically, but when an attempt was made to extend the flaps to 25 degrees, the hydraulic pressure dropped to zero. The crew then placed the hydraulic system selector to the No. 3 position (flap and gear downlock) and continued the approach.
The Accident
After touchdown, the throttles were placed in the idle reverse thrust position. When power was applied, the aircraft experienced an uncontrollable deviation from the runway.
Probable Cause
The official finding by the Civil Aeronautics Board determined the probable cause of this accident was the asymmetric thrust which, during a hydraulic emergency, resulted from the failure of the thrust reversers on engines No. 1 and 2 when reverse thrust was selected. A contributing factor was the failure of the first officer to monitor the thrust reverse indicator lights when applying reverse thrust.