Jakarta - A third pilot was on a Lion Air flight that encountered technical problems the night before the same plane crashed into the sea on October 29, Indonesia crash investigators said Thursday.
A different crew piloted the Boeing 737 Max 8 on its fatal last flight and was unable to fix reportedly similar problems, causing the plane to plummet into the Java Sea, killing 189 people.
"It is true there was another pilot in the cockpit during the flight [from Bali to Jakarta]," said Soerjanto Tjahjono, head of the National Transportation Safety Committee (KNKT).
The third pilot was an off-duty staffer who was returning from Bali to Jakarta and was qualified to fly the Max 8.
"The pilot has been interviewed by KNKT but we will not disclose the content of the interview," Soerjanto said.
The news agency Bloomberg reported on Wednesday, citing two unnamed sources, that the extra pilot correctly diagnosed the problem and told the crew how to disable a malfunctioning flight-control system and save the plane.
The off-duty pilot told the crew to cut power to the motor in the trim system that was driving the nose down, the report said.
A preliminary report on the accident released in November revealed that the pilots of the doomed flight tried to pull the aircraft back up repeatedly as the aircraft's automatic nose-down manoeuvre was activated.
Investigators have focused on the role of a new feature in the Boeing aircraft, known as the manoeuvring characteristics augmentation system (MCAS), in the crash.
The system has been installed by Boeing on its latest generation of 737 to prevent the plane's nose from getting too high and causing the aircraft to stall.
But in the fatal incident last month, it appeared to have forced the nose down after receiving erroneous information from sensors.
On March 10, a Max 8 operated by Ethiopian Air crashed, killing all 157 people on board. There are concerns that a similar malfunction may have caused the crash.
Tjahjono declined to comment on remarks by Ethiopian Transport Minister Dagmawit Moges that there were "clear similarities" between the Ethiopian Airlines crash and the Lion Air crash.
"If there's a new development and KNKT has access to information on the ET302 accident, we will look into and analyse it thoroughly to complement our investigation into the Lion Air crash," he said.
Tjahjono also denied a news report that the pilots of the crashed flight scrambled through a handbook before it hit the water.
But another KNKT investigator, Nurcahyo Utomo, said the crew looked up the handbook for the right checklist as they tried to control the aircraft.
"Based on the CVR, we can assume that for the most part of the flight, they were calm," Nurcahyo told reporters.
"In the last few seconds of the flight, it seemed they panicked after they realized they could not recover the aircraft," he added.dpa