Lufthansa Flight 540 was a scheduled commercial flight for
Lufthansa, serving the
Frankfurt
Frankfurt, officially Frankfurt am Main (; Hessian: , " Frank ford on the Main"), is the most populous city in the German state of Hesse. Its 791,000 inhabitants as of 2022 make it the fifth-most populous city in Germany. Located on it ...
–
Nairobi
Nairobi ( ) is the capital and largest city of Kenya. The name is derived from the Maasai phrase ''Enkare Nairobi'', which translates to "place of cool waters", a reference to the Nairobi River which flows through the city. The city proper h ...
–
Johannesburg
Johannesburg ( , , ; Zulu and xh, eGoli ), colloquially known as Jozi, Joburg, or "The City of Gold", is the largest city in South Africa, classified as a megacity, and is one of the 100 largest urban areas in the world. According to Dem ...
route.
On 20 November 1974, the
Boeing 747-130
The Boeing 747 is a large, long-range wide-body aircraft, wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States between 1968 and 2022.
After introducing the Boeing 707, 707 in October 1958, Pan Am w ...
that was operating as Flight 540 was carrying 157 people (140 passengers and 17 crew members) crashed and caught fire shortly after taking off from
Jomo Kenyatta International Airport
Jomo Kenyatta International Airport , is an international airport in Nairobi, the capital of and largest city in Kenya. The other three important international airports in Kenya include the Kisumu International Airport,
Moi International Airp ...
in
Nairobi
Nairobi ( ) is the capital and largest city of Kenya. The name is derived from the Maasai phrase ''Enkare Nairobi'', which translates to "place of cool waters", a reference to the Nairobi River which flows through the city. The city proper h ...
for the last leg of the flight, resulting in the deaths of 55 passengers and 4 crew members. This was the first fatal accident involving a Boeing 747.
Aircraft and crew
Aircraft
The aircraft involved was a Boeing 747-130 registered as D-ABYB and was named ''Hessen.'' It was the second 747 to be delivered to Lufthansa. It made its first flight on 30 March 1970 and was delivered to Lufthansa on 13 April the same year. The aircraft was powered by four Pratt and Whitney JT9D-7
turbofan engines
The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which achieves mechanical ...
. The aircraft had 16,781 flying hours at the time of the accident.
Crew
The flight crew consisted of 53-year-old captain Christian Krack (who had more than 10,000 flight hours, with 1,619 hours on the Boeing 747), 35-year-old first officer Hans-Joachim Schacke (3,418 flight hours, with more than 2,000 hours on the Boeing 747) and 51-year-old flight engineer Rudolf (Rudi) Hahn (13,000 hours of flying experience).
Accident
As the aircraft was making its takeoff from runway 24 at the
Jomo Kenyatta International Airport
Jomo Kenyatta International Airport , is an international airport in Nairobi, the capital of and largest city in Kenya. The other three important international airports in Kenya include the Kisumu International Airport,
Moi International Airp ...
in Nairobi, the pilots felt a
buffeting vibration. The captain continued the climb and retracted the
landing gear
Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...
. 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 from the end of the runway, the 747 airplane crashed in the grass. It then struck an elevated access road and broke up. The left wing exploded and fire spread to the fuselage. 55 of the 140 passengers and 4 of the 17 crew members died.
Cause
The cause of the crash was determined to be a stall caused by the leading edge
slats (strictly speaking, outboard variable camber
leading-edge slats and inboard
Krueger flaps) having been left in the retracted position. Even though the trailing edge flaps were deployed, without the slats being extended the aircraft's stall speed was higher and the maximum
angle of attack was lower. As a result, the aircraft was unable to climb out of
ground effect. The flight engineer was found to have failed to open the slat system bleed air valves as required on the pre-flight checklist. This prevented bleed air from flowing to the 747's pneumatic slat system and, since the leading edge slats on the 747 are pneumatically driven, kept it from deploying the leading edge slats for takeoff. The
takeoff warning system, which would have sounded an alarm if the flaps had not been set for takeoff, did not have a separate warning that the slats' pneumatic valve had not been opened by the flight engineer.
The faulty state of the slats should by design have been indicated by yellow warning lights: one for the pilot, and eight for the flight engineer. However, both crew members stated in court that these lights had been green. Three possible explanations have since been offered for this inconsistency: that the morning sun was blinding the cockpit crew and thus hampered color perception, that a construction error could have caused green lights despite the retracted slats, and that the crew lied. None of these possibilities could be conclusively proven. The flight crew was blamed for not performing a satisfactory pre-takeoff checklist, but the accident report also faulted the lack of adequate warning systems that 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
The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and p ...
added systems to warn pilots if the slat valve had not been opened prior to takeoff.
Captain Krack and flight engineer Hahn were dismissed from Lufthansa shortly after, but their dismissals were overturned by a labor court, as there was no investigation report available to rule out the chances of a technical defect.
Flight engineer Hahn was charged with criminal negligence, but was acquitted in 1981. This marks the first crashed Boeing 747.
See also
*
List of aircraft accidents and incidents resulting in at least 50 fatalities
Bibliography
*
The final report is this work:
* "Report on Accident to Boeing 747 Registered D-ABYB which occurred on 20th November 1974 at Nairobi Airport, Kenya."
East African Community
The East African Community (EAC) is an intergovernmental organisation composed of seven countries in the Great Lakes region of East Africa: the Democratic Republic of the Congo, the United Republic of Tanzania, the Republics of Kenya, Burun ...
Accident Investigation Branch (Nairobi), 1976.