UK investigators have determined that the crew of a Let L-410 opted to land at the Isle of Man in a crosswind double the maximum demonstrated certification level.
The aircraft rolled considerably as it approached the runway and, after touching down, its right-hand main gear lifted, causing the left wing-tip of the high-wing aircraft to come within 1m (3ft) of the runway surface.
Investigators found the Van Air Europe aircraft had been cleared to land on Ronaldsway airport's runway 26, but that its crew was informed of winds from 300° at 41kt, gusting 31-63kt – giving a crosswind component of 40kt.
While this was twice the maximum demonstrated component of 19.4kt for the turboprop, the carrier "did not apply" a limiting component of crosswinds to its operations, says the UK Air Accidents Investigation Branch.
It adds that there is "no evidence" that crews were trained to handle the aircraft in crosswinds higher than 19.4kt.
The only wind limit applied and used by the crew was 45kt for ground operations.
Such was the concern from air traffic control that the aircraft was approaching in winds substantially higher than this ground limit that it put fire and rescue vehicles on standby.
The Isle of Man safety regulator also intervened immediately after the landing, ordering the aircraft to halt as it left the runway, because it believed gusts of 63kt could cause an accident during taxiing.
While neither pilot nor the three passengers on the aircraft were injured, the UK Civil Aviation Authority – which had already been scrutinising the operator – suspended the Czech airline's foreign carrier permit after the incident and ordered it to suspend UK commercial air transport services indefinitely.
The L-410 had been returning to the Isle of Man, following an aborted approach to Belfast City airport, on 23 February last year.
Belfast City had been experiencing gusting winds, up to 43kt, as a consequence of the same storm system which affected the Isle of Man.
"Continuous moderate turbulence was experienced during the approach and, at all times, the reported wind significantly exceeded the maximum demonstrated crosswind component by a significant margin," says the inquiry.
The L-410 executed a go-around at 20ft after being destabilised by a strong crosswind, but the inquiry says the conditions were such that a missed approach would normally be initiated earlier.
Investigators have also identified other shortcomings in the preparation and execution of the flight. Although the Czech civil aviation authority has detailed a number of safety actions completed by the operator, the UK inquiry believes a number of operational control and supervision issues "still require attention".
"While this investigation highlighted certain of the operator's policies and procedures which did not comply with regulatory requirements, it is possible that there are areas outside the scope of this investigation that may also require review," it adds.
Van Air's operational processes and training should be reviewed by the Czech authorities, it recommends, to ensure that they are compliant with commercial air transport regulations.