United Airlines Flight 585 (Essay Sample)

United airlines flight 585
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United Airlines Flight 585
United airlines flight 585 was an American aircraft, particularly Boeing 737-291, scheduled to transport passengers to Colorado Springs Municipal Airport. The aircraft originated from Stapleton International Airport in Denver. The accident took place on March 3, 1991 when it was just about to land at runway 35 in the destination airport. It had a registration number N999UA, changed from N7356F when it was registered to Frontier Airlines (FOX21, 2011). The aircraft was transporting five crew members and 20 passengers and none survived the accident bringing the total survivors to 25 (Nytimes.com, 2014). There was a report to a nearby control tower from a Cessna pilot “We just saw the plane…uh just suddenly complete a downward dive" (Airdisaster.com, 2014). Reports indicated that the aircraft took a straight drop as reported by Kelvin Ford, the air traffic controller.
Captain Harold Green aged 52 and Patricia Edison aged 42, piloted the aircraft. The rest of the crew included Anita Lucero, Lisa Church and Monica Smiley. Captain Harold, the leading pilot, had over 10,000 flying hours. He was classified as a pilot compliant to the flight rules and procedures. On the other hand, Patricia Edison, the first officer had over 4,000 flying hours. Therefore, both aviators had adequate training and experience to handle the aircraft.
Boeing 737-291 History
On February 25, that aircrafts rudder deflected mysteriously to the right where the pilots in control turned off the yaw dumper, which instantaneously adjusted the rudders during flight stabilizing the aircraft. The incident prompted the technicians to replace the yaw dumper before the aircraft went for the next flight. On 27 February, the crew members noted that the rudder had stability problems necessitating replacement of a valve positioned in the yaw dumper before the next flight.
Accident Scene
Flight 585 made stops at Denver and Illinois. After takeoff at exactly 0943 hours, the aircraft began to roll towards the right and its nose pitched down. The pilot kept the flaps at 15 degrees to enable the aircraft to take a go-around; moreover, the crew increased the thrust. However, their attitude decreased fast causing the airplane to plunge into Widefield Park that was near the point of takeoff (Pulitzer.org, 2014).
Accident Investigations
The National Transport and Safety Board (NTSB) carried out official investigations over a period of 21 months (Ntsb.gov, 2014). The flight data was retrieved from the flight data recorder despite the damage in the protective cover. Investigators considered five parameters namely altitude, heading, normal acceleration, airspeed and microphone keying. However, investigators were unable to develop a concrete reason for the head dive.
The alternate hypothesis proposed rotor winds from Rocky Mountains that were near the point of takeoff. Investigators also proposed collapse of the rudder power control unit that led to the reversal of the rudder; however, there was inadequate evidence to support the proposed hypothesis. On 8 December 1992, NTSB submitted a report stating that the investigations led to unclear results that did not bring forth any substantial results to speculate probable cause. However, there were reports that the NTSB lacked enough knowledge on the modeling of the rudder control system, particularly during the recovery of parts in the wreckage (Airdisaster.com, 2014).
Probable Cause
The NTSB started another investigation into the probable cause of the UAL 585 accident after the crash of another Boeing 737. Thus, the investigators concluded that the crash was caused by the malfunction of the plane’s rudder control unit. The other accident was also caused by the same cause. The malfunction of the rudder control unit caused the crew to lose charge of the aircraft. Investigators speculated that the rudder surface deflected in the opposite direction to that initiated by the crew creating the servo valve to slide on to the major rudder power control unit servo valve. Thus, the aircraft lost its neutral position.
The aircraft took a “split-S” plunge into the ground usually caused by loss of symmetry during flight. The loss of symmetry caused the right wing or engine to break away; however, that had not yet happened. The symmetry could only be corrected by positioning the rudder to the far right, which was fatal considering the plane was around 1000 feet from the ground. Investigators also found loose circuits in the power control unit that the investigators associated with irregular rudder yaws. There was clear wind shear caused by the mountain ranges that may have led to the...