Lufthansa Flight 540
Encyclopedia
Lufthansa Flight 540 was a scheduled commercial flight for Lufthansa
operated with a Boeing 747-130, carrying 157 people (140 passengers and 17 crew members). The flight was operating the final segment of its Frankfurt
–Nairobi
–Johannesburg
route. On 20 November 1974 it crashed and caught fire shortly past the runway
on takeoff. This was the first ever crash and third hull loss of a Boeing 747
.
As the aircraft was making its takeoff from runway 24 at the Jomo Kenyatta International Airport
in Nairobi, the pilots felt a buffeting vibration. The captain continued the ascent and retracted the landing gear
. However, as this was being done, the aircraft started to descend and the stall warning system light came on. The aircraft continued to descend and approximately 3700 feet (1,127.8 m) from the end of the runway, the 747 grazed bushes and grass. It then struck an elevated access road and broke up. The left wing exploded and fire spread to the fuselage. Of the 157 people aboard, 59 perished (55 passengers and 4 crew members).
Efforts by crew members saved a number of lives. Thomas C. Scott, a commercial pilot working the flight as a cabin crew member, was credited with saving the lives of a dozen passengers before the fuselage exploded by carrying the injured and escorting the dazed.
The cause of the crash was determined to be a stall caused by the leading edge flaps
having been left in retracted position. Without leading edge flaps deployed, the aircraft's stalling angle of attack
was much lower, especially at a hot and high
airport like Nairobi's with its airport elevation of 5327 feet (1,624 m). The thinner air at higher altitudes generates less lift
and further degrades the aircraft's ability to handle high angles of attack, as well as reducing the thrust
provided by the 747's four turbofan engines.
The elevation and temperature at the airport were within the capability of the 747, but only with leading and trailing edge flaps extended. With the leading edge flaps retracted, the aircraft lacked sufficient lift and thrust to continue climbing once out of the ground effect found near the surface. The flight engineer was found to have failed to open the engine bleed air valves as required on the pre-flight checklist. This prevented bleed air from flowing to the 747's pneumatic system and since the leading edge flaps on the 747 are pneumatically driven, kept it from deploying the leading edge flaps for takeoff.
The flight crew was blamed for not performing a satisfactory pre-take-off checklist, but the accident report also faulted the lack of adequate warning systems which could have alerted the crew to the problem. Two previous occurrences of this error had been reported, but in those cases the pilots had been able to recover the aircraft in time. After this third, deadly incident Boeing
added systems to warn pilots if such conditions existed prior to takeoff.
Lufthansa
Deutsche Lufthansa AG is the flag carrier of Germany and the largest airline in Europe in terms of overall passengers carried. The name of the company is derived from Luft , and Hansa .The airline is the world's fourth-largest airline in terms of overall passengers carried, operating...
operated with a Boeing 747-130, carrying 157 people (140 passengers and 17 crew members). The flight was operating the final segment of its Frankfurt
Frankfurt
Frankfurt am Main , commonly known simply as Frankfurt, is the largest city in the German state of Hesse and the fifth-largest city in Germany, with a 2010 population of 688,249. The urban area had an estimated population of 2,300,000 in 2010...
–Nairobi
Nairobi
Nairobi is the capital and largest city of Kenya. The city and its surrounding area also forms the Nairobi County. The name "Nairobi" comes from the Maasai phrase Enkare Nyirobi, which translates to "the place of cool waters". However, it is popularly known as the "Green City in the Sun" and is...
–Johannesburg
Johannesburg
Johannesburg also known as Jozi, Jo'burg or Egoli, is the largest city in South Africa, by population. Johannesburg is the provincial capital of Gauteng, the wealthiest province in South Africa, having the largest economy of any metropolitan region in Sub-Saharan Africa...
route. On 20 November 1974 it crashed and caught fire shortly past the runway
Runway
According to ICAO a runway is a "defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft." Runways may be a man-made surface or a natural surface .- Orientation and dimensions :Runways are named by a number between 01 and 36, which is generally one tenth...
on takeoff. This was the first ever crash and third hull loss of a Boeing 747
Boeing 747
The Boeing 747 is a wide-body commercial airliner and cargo transport, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first wide-body ever produced...
.
As the aircraft was making its takeoff from runway 24 at the Jomo Kenyatta International Airport
Jomo Kenyatta International Airport
-Charter airlines:-Cargo airlines:-Other facilities:The Kenya Civil Aviation Authority has its head office in the KAA Complex on the airport property. African Express Airways has its head office on the airport property...
in Nairobi, the pilots felt a buffeting vibration. The captain continued the ascent and retracted the landing gear
Landing Gear
Landing Gear is Devin the Dude's fifth studio album. It was released on October 7, 2008. It was his first studio album since signing with the label Razor & Tie. It features a high-profile guest appearance from Snoop Dogg. As of October 30, 2008, the album has sold 18,906 copies.-Track...
. However, as this was being done, the aircraft started to descend and the stall warning system light came on. The aircraft continued to descend and approximately 3700 feet (1,127.8 m) from the end of the runway, the 747 grazed bushes and grass. It then struck an elevated access road and broke up. The left wing exploded and fire spread to the fuselage. Of the 157 people aboard, 59 perished (55 passengers and 4 crew members).
Efforts by crew members saved a number of lives. Thomas C. Scott, a commercial pilot working the flight as a cabin crew member, was credited with saving the lives of a dozen passengers before the fuselage exploded by carrying the injured and escorting the dazed.
The cause of the crash was determined to be a stall caused by the leading edge flaps
Flap (aircraft)
Flaps are normally hinged surfaces mounted on the trailing edges of the wings of a fixed-wing aircraft to reduce the speed an aircraft can be safely flown at and to increase the angle of descent for landing without increasing air speed. They shorten takeoff and landing distances as well as...
having been left in retracted position. Without leading edge flaps deployed, the aircraft's stalling angle of attack
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...
was much lower, especially at a hot and high
Hot and high
In aviation, hot and high is a condition of low air density due to high ambient temperature and high airport elevation. Air density decreases with increasing temperature and altitude. Lower air density reduces the amount of lift generated by the wings or the rotors of an aircraft, which may hamper...
airport like Nairobi's with its airport elevation of 5327 feet (1,624 m). The thinner air at higher altitudes generates less lift
Lift (force)
A fluid flowing past the surface of a body exerts a surface force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the surface force parallel to the flow direction...
and further degrades the aircraft's ability to handle high angles of attack, as well as reducing the thrust
Thrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a force of equal magnitude but opposite direction on that system....
provided by the 747's four turbofan engines.
The elevation and temperature at the airport were within the capability of the 747, but only with leading and trailing edge flaps extended. With the leading edge flaps retracted, the aircraft lacked sufficient lift and thrust to continue climbing once out of the ground effect found near the surface. The flight engineer was found to have failed to open the engine bleed air valves as required on the pre-flight checklist. This prevented bleed air from flowing to the 747's pneumatic system and since the leading edge flaps on the 747 are pneumatically driven, kept it from deploying the leading edge flaps for takeoff.
The flight crew was blamed for not performing a satisfactory pre-take-off checklist, but the accident report also faulted the lack of adequate warning systems which could have alerted the crew to the problem. Two previous occurrences of this error had been reported, but in those cases the pilots had been able to recover the aircraft in time. After this third, deadly incident Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
added systems to warn pilots if such conditions existed prior to takeoff.