1955 MacArthur Airport United Air Lines crash
Accident | |
---|---|
Date | April 4, 1955 |
Destination | LaGuardia Airport, New York City, New York, United States[2] |
Crew | 3[4] |
Fatalities | 3[4] |
Survivors | 0 |
On April 4, 1955, a United Airlines Douglas DC-6 named Mainliner Idaho crashed shortly after taking off from Long Island MacArthur Airport, in Ronkonkoma, Islip, New York, United States.
The flight was operated for the purpose of maintaining the currency of the instrument rating of two of the airline's pilots. Shortly after takeoff and only seconds after climbing through 150 feet (46 m), the plane began banking to the right. It continued to roll through 90 degrees; the nose then dropped suddenly and moments later it struck the ground. All three members of the flight crew were killed upon impact.
An investigation found a simulated
In the aftermath of the accident, the
History
On April 4, 1955, a United Airlines check captain, Stanley C. Hoyt, age 45, was carrying out
The weather on the day of the accident was clear, although there was a strong wind of about 20 knots (37 km/h) hitting the airfield from the southwest, with occasional gusts of wind as fast as 30 knots (56 km/h).[3] The aircraft made several circuits, taking off and landing again, before eyewitnesses observed the aircraft standing at the end of the runway and then taking off at about 15:50 Eastern Standard Time.[3][4] The takeoff weight was around 61,000 pounds (28,000 kg), far below the aircraft's maximum permissible weight and the center of gravity was within the prescribed limits for the model of aircraft.[3][5]
Between 1,500 feet (460 m) and 1,800 feet (550 m) down the runway, the aircraft reached
Investigation
Wreckage examination
The Civil Aeronautics Board (CAB), charged with investigating the accident, examined the wreckage at Long Island MacArthur Airport. Reports from witnesses of the crash indicated the aircraft appeared to have made a normal takeoff and began climbing normally. But, moments later it began banking sharply to the right. Investigators examined the four charred engines and concluded all were producing power at the point of impact.[3][5] They could not conclusively determine the amount of power being produced, but stated there was no evidence found in the wreckage that suggested the engines might have suffered an operational failure.[5][6]
They were also able to determine all of the flight control surfaces, including the elevators, ailerons and rudder, were functioning properly at the point of the crash, and there were no faults in the flight control system. The flaps were extended to between 15° and 20°, the standard setting for take-off. The propeller blades of No. 4 engine— on the far right side of the aircraft—were reversed—minus 8°, while the blades of Nos. 1, 2 and 3 engines were at 34° positive pitch (also standard for take-off).[5][6]
Reversed thrust
The propellers of a DC-6 are designed to provide reverse thrust after the aircraft touches down. The pilot then retards the throttle levers to a point below idle speed and that directs the electric mechanisms in the propeller hub to rotate the blades to a position in which they will provide reverse thrust.[6] Should the pilot need to perform a go-around, he moves the thrust levers forward to a positive position again and that will produce forward thrust, enabling the pilot to execute a go-around maneuver.[6]
The Douglas Aircraft Company designed a system that would prevent the accidental reversal of propeller blades in-flight. During development of the DC-6, the company installed a system that cut electrical power to the mechanisms which rotated the blades while the airplane was in the air. When there was enough weight on the landing gear (which would only be the case when the aircraft was on the ground), a switch which supplied electrical power to the mechanisms was closed—meaning that when the aircraft touched down the blades could be reversed and thus the airplane could be slowed. When the switch was closed, a red flag would swing into view in the cockpit of the aircraft, warning the crew that the blades could be reversed. Should the switch fail to close upon landing, the flag could be raised manually and electrical power to the mechanisms would be restored. When the aircraft took off, electrical power would be cut to the mechanisms so that the propeller blades could not be inadvertently reversed, and the red flag swung out of sight. Reverse thrust warning lamps, which would have warned the crew if the propellers were reversed, were not fitted on Mainliner Idaho.[6]
Flight tests
The CAB carried out flight tests using a DC-6. They found that if the propellers were reversed prior to take-off they would not, if the flag was not raised, be rotated automatically again in the air to produce forward thrust if full power was applied. Tests performed by United Airlines showed that, if the propellers of just one engine were reversed and full power was applied to all four engines, then the aircraft would spiral into a dive. If METO (maximum except take-off) power was applied to Nos. 1, 2 and 3 engines, and full reverse thrust was applied to engine No. 4, then the aircraft would become uncontrollable.[5][7]
If full left
"The flight tests showed conclusively that, at take-off configuration, a DC-6 becomes uncontrollable with an outboard engine at full power with its propeller in reverse pitch. Control is lost so quickly that there is little the crew can do at low altitude. In the case of this accident, it was doubtful if there would have been time for forward thrust to be restored before control was lost."
— Macarthur Job, Air Disaster Vol. 4, 2001[7]
Conclusions
While the wreckage was being examined, investigators found that all four engines were producing thrust at the time of impact. There were only two ways that the propeller could be reversed during the take-off sequence. Investigators ruled out electrical malfunction since, after detailed examination of the engine hub, there was no evidence found of this happening.
The investigation concluded the accident sequence began when the check pilot, while the aircraft was on the ground, retarded the throttle lever for No. 4 engine past the idle position, and therefore reversed the propellers of that engine. Once the airplane took off and started banking to the right, it would have been a natural reaction for one of the flight crew to increase power to No. 4 engine, thinking that by doing so the engine would start producing positive thrust and the aircraft could be recovered. However, since the metal flag was not raised, there was no electrical power to the rotating mechanisms—and increasing power to No. 4 engine would only have created more reverse thrust.[5][8]
The final accident report concluded there wasn't sufficient time for the crew to react, since the dive began suddenly while the plane was so close to the ground. "Control will be lost so quickly that there is little, if anything, that the pilot can do if it occurs at low altitude," the report stated. "He must recognize what is occurring, analyze it, and take action to unreverse in a very limited amount of time. It is doubtful that unreversing could have been accomplished in this instance before control was lost."[5]
On October 4, 1955, the CAB released the final accident report, which concluded the reversal of the propellers and subsequent increase in power of the No. 4 engine had caused the accident.[5]
"The Board determines that the probable cause of this accident was unintentional movement of No. 4 throttle into the reverse range just before breaking ground, with the other three engines operating at high power output, which resulted in the aircraft very quickly becoming uncontrollable once airborne."
— Civil Aeronautics Board, Accident Investigation Report; United Air Lines, Inc., MacArthur Field, Islip, New York, 1955[5]
Aftermath
Technological advances
Following the accident, the
United Airlines issued a statement saying it had begun installing the device on its fleet of DC-6 and DC-6B aircraft one week before the accident, having used it successfully in service on their fleet of Douglas DC-7 aircraft. A Martin bar had not yet been fitted on Mainliner Idaho.[7] United Airlines also said a program had begun to install reverse thrust indicator lights on all their DC-6 and DC-6B aircraft. The signals, fitted in the cockpit of the aircraft, would have warned the flight crew that the thrust lever had been pulled back too far, and the propellers had been reversed.[5]
Similar accidents
Since the crash, there have been several
See also
References
- Notes
- ^ a b "Archives 1955 Jan-Jun". Aircraft Crashes Record Office. Archived from the original on September 1, 2011. Retrieved December 26, 2010.
- ^ Aviation Safety Network. Archivedfrom the original on June 6, 2011. Retrieved October 22, 2010.
- ^ a b c d e f g h Job 2001, p. 45.
- ^ a b c "L. I. Crash Kills 3 Veteran Airline Pilots On Take-Off During Routine Check Hop". New York Times. April 5, 1955. Archived from the original on July 23, 2018. Retrieved December 26, 2010.(subscription required)
- ^ a b c d e f g h i j k l m n o p q r s "Accident Investigation Report; United Air Lines, Inc., MacArthur Field, Islip, New York, April 4, 1955". Civil Aeronautics Board. October 4, 1955. Retrieved June 1, 2021. – PDF
- ^ a b c d e Job 2001, p. 46.
- ^ a b c d Job 2001, p. 47.
- ^ a b c Job 2001, p. 49.
- ^ "Aircraft Accident Report: United Airlines Flight 859". Civil Aeronautics Board. July 16, 1962. Retrieved January 28, 2016.
- ^ "Accident Database: Accident Synopsis 02091982". Archived from the original on 2015-03-30. Retrieved 2011-07-11.
{{cite web}}
: CS1 maint: unfit URL (link) - ^ COCKPIT FIGHT REPORTED ON JET THAT CRASHED IN TOKYO Archived 2008-05-02 at the Wayback Machine", The New York Times. February 14, 1982. Retrieved on June 24, 2011.
- ^ "Troubled Pilot". Time. 1982-03-01. Archived from the original on 2008-05-02. Retrieved 2007-04-20.
- ^ "Final Accident Report". Archived from the original on 2011-07-22. Retrieved 2011-07-11.
- ^ "Lauda Air B767 Accident Report". Aircraft Accident Investigation Committee of Thailand. Archived from the original on June 7, 2011. Retrieved January 23, 2011.
- Aviation Safety Network. Archivedfrom the original on January 23, 2009. Retrieved January 23, 2010.
- Bibliography
- ISBN 1-875671-48-X.
External links