On Dec. 28, 1978, United flight 173 was approaching Portland after an evening flight from Denver. The Douglas DC-8 was operated by an experienced flight crew with a combined total of over 35,000 flight hours between the three. As the crew lowered the landing gear for their approach, a loud thunk was heard and a shudder was felt throughout the aircraft. The crew requested a holding pattern to diagnosis the issue and prepare for a potential emergency landing. The aircraft then spent the next hour circling above the skies of Portland as the flight crew attempted to fix the issue that had caused the vibrations and noise.
As the flight crew lined up for final into Portland, the number one and number two engine flamed out, shortly followed by both number three and four. The aircraft began gliding into suburban Portlandia and crashed into a wooded area, six miles south of the airport. Of the 189 passengers and crew, there were ten fatalities. The investigation found that the quad engine failure was caused by fuel exhaustion. But how could an experienced crew allow their fuel load to become so low?
The NTSB released the following as a probable cause, “The failure of the captain to monitor properly the aircraft’s fuel state and to properly respond to the low fuel state and the crew member’s advisories regarding fuel state. This resulted in fuel exhaustion to all engines. His inattention resulted from preoccupation with a landing gear malfunction and preparations for a possible landing emergency” and released a contributing factor of, “The failure of the other two flight crew members either to fully comprehend the criticality of the fuel state or to successfully communicate their concern to the captain.”
In short, the flameout was caused by the captain failing to monitor the fuel levels during the hour-long hold, as well as the other two flight crew members failing to communicate the problem to the captain.
The crash of United flight 173 became a catalyst for the industry. In 1981, United introduced the first crew resource management program in the industry. The goal of Crew Resource Management (CRM) is to reduce accidents due to pilot error. It encourages first officers and other crew members to respectfully question the captain. It creates a more harmonious and safer cockpit. Instead of having the captain make decisions unchallenged, CRM training allows for the first officer to have input on a situation. It also encourages flight crews to work as a team rather than separate units with one decisive leader.
In the case of United flight 173, the cockpit voice recording revealed that the first officer and the flight engineer attempted to alert the captain to the fuel situation, however, their fear of disrespecting the more senior and experienced captain led to them being ineffective. A similar crash occurred nearly six years earlier that was eerily similar: Eastern Air Lines flight 401 crashed into the Florida Everglades as all five crewmembers on the flight deck became preoccupied with a burned out light bulb. They failed to notice their unexpected descent until the very last minute.
Proper CRM procedures would have said that at least one of the Eastern 401 crew members was flying the aircraft and monitoring the flight instruments. Since the inception of CRM, it has been implemented industry-wide, and the number of aircraft crashes caused by pilot error have seen a large reduction. Although many passengers do not know about it, CRM is seen in every cockpit, from commuter airlines to the majors, and because of its implementation flying and air travel has become much safer.