The cockpit voice recorder from the crashed Lion Air Boeing 737 MAX 8 has revealed more details about how the crew attempted to solve the aircraft’s repeated descents.
Unnamed sources cited by Reuters said the CVR indicated the pilots were searching through checklist to identify the problem. Although the CVR transcripts have not been released by the Indonesian authorities, who said they will be included within a report on the October 2018 crash is due to be released in August.
An initial report released in November 2018 included information from the flight data recorder, but not the CVR, which was retrieved in January but had been damaged. The report indicated that faulty information from certain sensors caused the MCAS to trim the nose down.
The recorder data suggests that the crew responded with trim inputs via their control columns. These raised the nose up, but the MCAS will continue to trim nose-down until it senses the aircraft is no longer stalling.
The 737 has cut out switches on the centre console that disable the automatic trim and MCAS. When selected the switches on the 737 NG and MAX act as ‘runway stabiliser trim’ – quick-reference checklist.
Unconfirmed reports indicate that the first officer, then the pilot, read through checklists to find out why the control problem were occurring. They discussed airspeed and altitude, but not the trim moving the nose down. The source stated that the crew remained calm as they tried to solve the issue.