The Dutch Aviation Safety Board also criticised emergency training of pilots and air-traffic controllers.
The immediate cause of the October 1992 crash was metal fatigue in part of the pylon holding on the right-hand inner engine when the jet, which had just taken off from Schipol airport, reached a height of 6,500ft. Failure of the engine mountings caused the inner right engine to fall off and it knocked off the neighbouring engine.
When the pilots attempted a 360-degree turn to reduce height, they lost control and the jet hit an apartment block in Bijlmer, Amsterdam.
The investigators conclude there should be more training of pilots and air-traffic controllers to ensure that they take account of 'not only the safety of airplane passengers but also the risk to third parties especially (in) residential areas'.
As a result of the Amsterdam disaster and two similar incidents involving 747s, Boeing is adding an extra pylon on all 1,000 747s currently flying to prevent engines dropping off.