Incident Description
On 16 November 2004 at 0915 UTC, a Boeing 747-4Q8, registration G-VTOP, was parked at Stand 327 at London Heathrow Airport. The aircraft was preparing for a public transport passenger flight with 19 crew and 179 passengers aboard. Loading of the rear cargo hold had been completed. The high loader operator lowered the platform to raise the door locks, then raised it again to the hold door sill level and entered the hold to verify that stops and locks were correctly positioned. While inside, he heard a crushing noise behind him. Returning to the doorway, he saw that the platform had risen and damaged the cargo door frame and an adjacent cargo bin. He called for help, and a colleague activated the emergency stop button on the high loader.
Investigation
The airline's investigation determined that when the high loader operator released the control switch used to raise the platform, it did not return to neutral as designed but remained latched in the 'up' position. The platform probably continued to rise at a slower than normal speed, so the operator did not notice it was still moving upward when he stepped into the hold.
Corrective Action
Following the incident, all high loader vehicles operated by the ground handling company were modified to incorporate an override switch that must be engaged before the platform lift function can be activated.