Luxembourg's air navigation service failed to keep track of a maintenance vehicle before it was hit by a landing Boeing 747 freighter in low-visibility conditions, investigators have found.
Electrical maintenance personnel had been working on centreline lights and had parked a van on Luxembourg's runway 24, some 340m from the threshold.
The crew ran for cover when they heard the noise of the Cargolux 747-400F which was carrying out a Category IIIb approach after arriving from Barcelona on 21 January 2010.
Fog had reduced the runway visual range to just 350m (1,150ft) and, although one of the pilots briefly saw the van, the sighting came too late to take evasive action.
One of the 747's right-hand main-gear tyres hit the roof of the van during the flare, inflicting surface damage along the length of the vehicle. The pilots were unaware of the collision and the jet touched down safely, having only sustained cuts to the tyre.
Luxembourg's Administration of Technical Investigations says a shortage of resources led air navigation service ANA to schedule centreline lighting maintenance during normal operating hours. But it adds that the decision to pursue this work in low-visibility conditions, without hampering air traffic, "gave priority to flight operations over safety aspects".
The van had been cleared onto the runway, over the ground radio frequency, some 22min before the collision.
Investigators have not been able to piece together objectively the sequence of events which followed. According to two tower personnel, the van was instructed to vacate the runway while the 747 was still some 6-8min from landing.
"However, the [air traffic control] recordings show no trace of a communication during that specific period of time," says the inquiry. It adds that no communication was captured from the ground frequency in the time between the van's being cleared to enter the runway and the accident.
The inquiry could not determine whether tower controllers used memory aids to mark the van's presence on the runway.
Tower controllers said that they received a "carrier wave" audio signal on the ground frequency and assumed this meant the vehicle had vacated the area, but the inquiry could not establish the existence of the signal on recordings. Read-back procedures, to confirm the van had left the runway, were not applied.
Controllers could not see the collision through the fog - the van had been 1,900m from the tower - and were only made aware when the 747 pilot, after landing, mentioned a vehicle on the runway. One of the maintenance engineers also contacted the tower and, in subsequent conversations, explained that he "ran for his life", says the inquiry.
Luxembourg airport did not have surface surveillance equipment and the investigators state that procedures governing access of vehicles to the runway during low-visibility conditions were "inadequate".
There was a "lack of adequate co-ordination" between the control tower and the electrical maintenance department, the inquiry adds, which led to the tower controllers having "reduced" situational awareness.