The 293 travellers onboard were also warned to depart the aircraft “very slowly” in case the Boeing 747 toppled over following its unscheduled landing at Heathrow on January 30.

An Air Accidents Investigation report into the incident has now found that the aircraft’s landing gear lever had become stuck in the “up” position leading to only three of the five sets of wheels descended upon touching-down.

This lack of breaking power caused the aircraft to travel the entire length of the runway as it came to a halt, The Daily Mail reports.

The service had been due to fly to Chicago but had to turn back to the London terminal, south of Iceland, after the pilots reported technical problems.

On their way into Heathrow, the pilots reported an unsafe gear indication for both main gears as the aircraft’s nose and body wheels had descended.

The report blamed the fault on a mechanical error, stating: “that caused incorrect rigging of the landing gear lever system after the landing gear control module had been replaced.”

It added: “Passengers reported the crew advised they were returning to London due to a technical problem.

"About 20 minutes prior to landing the crew announced that the landing gear did not fully extend with only three of five sets of gear having lowered.

"After the aircraft was towed to the apron, passengers were told to disembark very slowly, aft cabin first, otherwise the aircraft would tip over and settle on its tail."

It continued: "The jammed landing gear lever was attributed to a rig pin not being inserted in the landing gear system during maintenance, which led to additional and unnecessary shims being used to rig the landing gear lever."

The report also believed that "the distraction of the engineer" and an "inadequate handover between the night shift and the day shift" had contributed to the incident.