The failure to repair a faulty navigational aid led to a jumbo jet crashing shortly after take-off from Stansted airport, according to an official accident report.
The plane's crew had correctly reported the fault at Stansted
All four people on board the cargo plane - two pilots, a flight engineer and a ground engineer - were killed in the crash in December 1999.
It was later confirmed that the plane was carrying hundreds of pounds of depleted uranium.
But investigators said at the time that it had remained intact and therefore did not pose a health hazard to emergency service workers or people living nearby.
The Air Accidents Investigation Branch report, published on Friday, said a fault had prevented the pilots of the Korean Air Boeing 747 from responding properly when the plane was in danger.
The crew, who had flown in from Tashkent had reported
the fault on landing, but maintenance work carried out at Stansted failed to rectify it.
The problem involved the attitude director indicator, which gives pilots an indication of the angle of the aircraft at night and in cloud.
The report said maintenance activity at Stansted was "misdirected" before take-off despite the fault being correctly reported.
Consequently, the captain received incorrect plane altitude information when he turned the plane to the left and this lead to it hitting the ground.
The report said that the "inexperienced" co-pilot, who was 33, did not alert the captain to the unsafe position the aircraft had been put into.
It was "a matter of conjecture" whether he had felt inhibited in bringing the situation to the attention of the captain, who was 57.
The report said a lack of clarity regarding responsibility relating to local engineering support for Korean Air's own engineering personnel, had resulted in "erroneous defect identification and misdirected maintenance action".
It made six safety recommendations to ensure a tightening up of safety procedures.