Investigators looking into Tuesday's Air France jet crash at Toronto airport are examining why only half of the plane's emergency exits were used.
All 309 passengers and crew aboard Flight 358 survived the crash
The Airbus A340 crashed in bad weather and fell into a ravine, but all of its 309 passengers and crew escaped.
Canada's lead investigator said that only four of the eight exits were used after a fire broke out onboard, forcing some to jump out of the plane.
Real Levasseur also said that two of the emergency slides failed to operate.
Emergency slides are supposed to unfold automatically when an exit door is opened, providing a means of escape for passengers.
But many of those on the plane said they had struggled to escape from the burning craft as some of the slides and exits were not working properly.
Mr Levasseur said experts were at the crash site examining whether the slides and doors were damaged ahead of the crash or during the impact.
The plane from Paris landed in a storm at Toronto's Pearson International Airport at 1603 local time (2003 GMT) on Tuesday.
After touching down on the runway, it lurched across the wet tarmac before skidding towards the airport perimeter.
The plane overshot the runway by about 200m (660ft) and came to rest with its tail pointing in the air in a ravine next to a busy motorway, Highway 401.
Moments after the last survivor clambered away from the jet, the fuselage was engulfed in smoke and flames.