On 20 November 1974, the Boeing 747-130 that was operating as Flight 540 was carrying 157 people (139 passengers and 18 crew members) crashed and caught fire shortly after taking off from Jomo Kenyatta International Airport in Nairobi, Kenya, for the last leg of the flight, resulting in the deaths of 54 passengers and 5 crew members.

[11][12][13][8] As the aircraft was making its takeoff from runway 24 at the Jomo Kenyatta International Airport in Nairobi, the pilots felt a buffeting vibration.

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.

The flight engineer was found to have failed to open the slat system bleed air valves as required on the pre-flight checklist.

[20] 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.

After this third, deadly incident, Boeing added systems to warn pilots if the slat valve had not been opened prior to takeoff.

[25] However, there are reliable indications that Lufthansa was already aware of possible problems with (false) displays concerning the slats a good six months before the Nairobi crash.