The pilots of two Bombardier Q400s that suffered landing gear collapses, behaved in an "exemplary manner" when it became clear that one of the main landing gear legs was not locked down.

Flight's operations and safety editor David Learmount explains in this video that the pilots knew that there was a real chance that the gear leg would collapse on landing, which meant the propeller on that side would hit the ground and shatter as the wingtip began to drop toward the ground.

"The gear on the Q400s that have done more than 10,000 flight cycles have received something of a battering over the years," he says, and these were the ones that have been grounded until the nature of the fault is established.

Learmount applauded the crew’s preparedness in averting disaster by following the standard procedure of using up almost all the fuel before making the approach, and moving passengers away from the cabin area closest to the propellers to reduce the chance of injury if pieces of the shattered propeller were to pierce the fuselage.

SAS has grounded all the Q400s in its fleet that had performed more than 10,000 flights pending individual inspection, and the manufacturer Bombardier immediately recommended the same to all other operators of the type.