Northwest Orient Airlines Flight 706
Encyclopedia
Northwest Orient Airlines Flight 706, registration N137US, was a Lockheed L-188 Electra
aircraft which crashed on take-off from Chicago
's O'Hare International Airport
September 17, 1961. All 37 on board were killed in the accident.
Flight 706 began its day in Milwaukee, Wisconsin
, and was scheduled to stop at Chicago before travelling to Tampa
, Fort Lauderdale, and Miami, Florida
. It arrived at Chicago in the early morning and left soon afterwards, being cleared for takeoff at 8:55 AM. Takeoff was normal until the aircraft reached the altitude of 100 feet above ground level, when witnesses noticed a slight change in the sound of the Electra's engines. The aircraft began a gentle bank to the right as the starboard wing began to drop. The bank angle increased to 35°; at that point the tower controllers picked up a garbled broadcast believed to be from the pilots. The aircraft climbed to approximately 300 feet but continued to bank, eventually reaching a bank angle of over 50°. At that point, the starboard wing nicked a series of high-tension power lines running along the south boundary of the airport; shortly after that, the aircraft struck an embankment and cartwheeled onto its nose, sliding tailfirst along a stand of trees before exploding into a ball of flame among the trees. The accident took less than two minutes from the beginning of takeoff until the final crash.
Investigators with the Civil Aeronautics Board determined that the cable physically connecting the first officer's control wheel to the aileron
boost unit had disconnected. This had caused the ailerons to put the aircraft in a starboard-wing-down attitude, and had prevented the pilots from being able to correct the bank. The cables attaching the pilots' control wheels to the aileron boost unit had been removed two months before the accident during routine maintenance; a safety cable that held part of the assembly together had not been replaced when the cables were hooked back up. The contact slowly separated, eventually completely failing during the takeoff sequence.
Lockheed L-188 Electra
The Lockheed Model 188 Electra is an American turboprop airliner built by Lockheed. First flying in 1957, it was the first large turboprop airliner produced in the United States. Initial sales were good, but after two fatal crashes which prompted an expensive modification program to fix a design...
aircraft which crashed on take-off from Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
's O'Hare International Airport
O'Hare International Airport
Chicago O'Hare International Airport , also known as O'Hare Airport, O'Hare Field, Chicago Airport, Chicago International Airport, or simply O'Hare, is a major airport located in the northwestern-most corner of Chicago, Illinois, United States, northwest of the Chicago Loop...
September 17, 1961. All 37 on board were killed in the accident.
Flight 706 began its day in Milwaukee, Wisconsin
Milwaukee, Wisconsin
Milwaukee is the largest city in the U.S. state of Wisconsin, the 28th most populous city in the United States and 39th most populous region in the United States. It is the county seat of Milwaukee County and is located on the southwestern shore of Lake Michigan. According to 2010 census data, the...
, and was scheduled to stop at Chicago before travelling to Tampa
Tampa, Florida
Tampa is a city in the U.S. state of Florida. It serves as the county seat for Hillsborough County. Tampa is located on the west coast of Florida. The population of Tampa in 2010 was 335,709....
, Fort Lauderdale, and Miami, Florida
Miami, Florida
Miami is a city located on the Atlantic coast in southeastern Florida and the county seat of Miami-Dade County, the most populous county in Florida and the eighth-most populous county in the United States with a population of 2,500,625...
. It arrived at Chicago in the early morning and left soon afterwards, being cleared for takeoff at 8:55 AM. Takeoff was normal until the aircraft reached the altitude of 100 feet above ground level, when witnesses noticed a slight change in the sound of the Electra's engines. The aircraft began a gentle bank to the right as the starboard wing began to drop. The bank angle increased to 35°; at that point the tower controllers picked up a garbled broadcast believed to be from the pilots. The aircraft climbed to approximately 300 feet but continued to bank, eventually reaching a bank angle of over 50°. At that point, the starboard wing nicked a series of high-tension power lines running along the south boundary of the airport; shortly after that, the aircraft struck an embankment and cartwheeled onto its nose, sliding tailfirst along a stand of trees before exploding into a ball of flame among the trees. The accident took less than two minutes from the beginning of takeoff until the final crash.
Investigators with the Civil Aeronautics Board determined that the cable physically connecting the first officer's control wheel to the aileron
Aileron
Ailerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector...
boost unit had disconnected. This had caused the ailerons to put the aircraft in a starboard-wing-down attitude, and had prevented the pilots from being able to correct the bank. The cables attaching the pilots' control wheels to the aileron boost unit had been removed two months before the accident during routine maintenance; a safety cable that held part of the assembly together had not been replaced when the cables were hooked back up. The contact slowly separated, eventually completely failing during the takeoff sequence.
External links and references
- Aircraft Accident Report on Flight 706 from the Department of Transport's Special Collections
- Air Disaster, Vol. 4: The Propeller Era, by Macarthur JobMacarthur JobMacarthur Job is an Australian aviation writer and air safety consultant. He has published nine books on aviation safety...
, Aerospace Publications Pty. Ltd. (Australia), 2001 ISBN 1-875671-48-X