The pilot and co-pilot of a Lion Air plane that crashed at Bali's airport have passed initial drug tests, an official said Monday, as investigators probe the causes of the accident that left dozens injured but no fatalities.
The Indonesian passenger jet carrying 108 people missed the runway as it came into land on the resort island Saturday, slamming into the water at high speed and splitting in two.
Investigators were due later Monday to haul the half-submerged wreckage onto a beach to examine the jet's interior and recover the cockpit voice recorder.
It is not yet clear what caused the accident, although analysts have speculated that it could have been caused by a weather phenomenon such as "wind shear", a change in wind direction and speed between different altitudes.
The pilot and co-pilot on the new Boeing 737-800 tested negative in urine tests for drugs and alcohol, said transport ministry spokesman Bambang Ervan. "We are still waiting for the hair tests," he added.
A Lion Air official said at the weekend that the Indonesian pilot, Mahlup Gozali, who had more than 10,000 flying hours, and the Indian co-pilot, Chiraq Carla, had been in a fit state to fly the plane.
Drug tests are routine following air accidents but at least three pilots at Lion Air, Indonesia's fastest-growing carrier which recently sealed two huge deals, have been arrested for either consumption or possession of methamphetamine since 2011.
Investigators and officials are still trying to determine what caused the plane to plunge into the sea, leaving terrified passengers to swim through the water to shore or be plucked to safety by police in rubber dinghies.
But analysts said that given mechanical problems were unlikely as the plane was new, the accident could have been caused by "wind shear", or a "microburst", a strong downdraft from storm clouds.
"If that hit the aircraft when it was on final approach, there is the likelihood the pilots would not have had time to recover," Tom Ballantyne, chief correspondent with Orient Aviation magazine, told AFP.
An airport forecaster told AFP the weather at the runway at the time of the accident was cloudy, but in general fine.
But Ballantyne added that phenomena such as "wind shear" were "invisible" and could occur in any weather conditions
Ervan refused to comment on what may have caused the crash.
He said that the independent investigation team probing the accident would take two to three months to reach a preliminary conclusion, and up to a year to produce final conclusions.