Reducing Pilot Error

On the evening of December 28th, 1978, United Airlines flight 173 was making its final approach into Portland, Oregon. Upon lowering the landing gear, only the nose-gear down indicator light illuminated green. No green lights came on for the main wheels. The approach was abandoned and the aircraft entered a holding pattern to sort out the problem. 

The captain, first officer and flight engineer assessed that they had just over an hours worth of fuel left and began alternate procedures to lower the main landing gear. These procedures were completed in about 30 minutes but there was no way to guarantee that the wheels were down and locked in place. The captain therefore remained in the mindset that the landing gear would collapse on landing.

With that in mind he prioritised time for the cabin crew to secure the cabin and prepare it for an emergency landing while the aircraft still circled 25 miles out from the airport. 

With 11 minutes worth of fuel left, the flight engineer expressed a need to get the plane on the ground but the captain still insisted on waiting for the cabin to be ready and preparing for an emergency landing. 

With just 5 minutes worth of fuel they finally began their approach to Portland and then with 19 miles to run to touchdown their number 4 engine flamed out. Shortly after that the number 3 engine shut down. They were now 12 miles from touchdown. A few moments later the first officer made a radio call “United 173 heavy, Mayday! We’re – the engines are flaming out! We’re going down! We’re not going to be able to make the airport!”  

The DC-8 crashed into a wooded area 6 miles short of the airport. Eight passengers, one cabin crew member and the flight engineer were killed and 23 other passengers were seriously injured. The landing gear problem was due to a burned out indicator light bulb in the cockpit. 

The main attributing factor to the crash was determined to be that of the captain getting so focused on preparing for a landing with collapsed landing gear that he failed to recognise the impending exhaustion of fuel. Although the first officer and flight engineer both made comments about the fuel state they were not strong enough to have an effect on the captain. 

As a result of this and other accidents in the past where crews have lost awareness in flight the subject of “Human Factors” is now a highly studied area and an integral and important part of pilot training. Knowing how to recognise the way in which the mind can be distracted and deceived by external indicators can reduce the chances of human error playing a part in future accidents and therefore reduce accident numbers in general. 

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