JAKARTA: A final Indonesian report on the fatal crash of Lion Air flight 610 published on Friday (Oct 25) details stress and confusion in the cockpit as the Boeing 737 MAX's MCAS software, misled by faulty sensor readings, repeatedly lowered the plane's nose.
Investigators pinpoint multiple flaws in the design and approval of the software while noting the captain was sick and the co-pilot was unfamiliar with emergency cockpit procedures.
Following are excerpts of a summary from the cockpit voice recording from the Oct 29, 2018, crash recovered by navy divers in January.
Oct 29, 5.18am
While still on the ground, the co-pilot informs the captain that this is not his usual schedule and that he was called at 4am that morning and told he would be on the flight.
The captain says he is suffering from the flu and is recorded coughing about 15 times during the pre-flight.
A Lion Air engineer comes to the cockpit and tells the captain he will be on board, but has not been trained for the Boeing 737 MAX 8.
The 181 passengers and seven crew are now all on board and the aircraft is ready to taxi.
The captain is at the controls and the co-pilot is handling the radio and speaking to ground control. Jakarta tower issues takeoff clearance and the plane leaves the runway at 6.20.33am.
Two seconds later, the stick shaker or stall alarm starts vibrating on the left side where the captain sits. A faulty Angle of Attack (AOA) sensor is feeding false data to a flight computer, which thinks the plane is in danger of losing lift.
The captain is recorded as "exclaiming about what happened to the aircraft", while the co-pilot tells him there is also a problem of inconsistent airspeed readings.
The co-pilot makes a similar exclamation and asks the captain, who does not respond, if he wants to return.
An air traffic controller clears the pilots to climb to 27,000 feet. Now the cockpit's altitude readings are described as inconsistent.
The co-pilot asks air traffic control for the reading on the radar display and is told they're at 900 feet as the aircraft was climbing.
The co-pilot is asked by the captain to run a memory checklist, the most urgent type of problem-solving procedure which pilots must know by heart, for unreliable airspeed values. There is no record in the transcript of him doing this.
Unsure what altitude to request from controllers, he is told by the captain to "request uuh..proceed".
Asked by air traffic control to describe the problem, the co-pilot replies they're experiencing "flight control problems".
The captain briefly hands control to the co-pilot, while air control warns the flight has descended to "ONE SEVEN HUNDRED" (1,700 feet) and asks for the intended altitude.
The captain requests 5,000 feet, which the co-pilot radios to control.
The controller instructs the pilots to climb and turn northeast. An automated cockpit voice alert warns the crew to watch the bank, or turning angle.
The captain again calls for a "memory item", but does not say which mental checklist he is referring to. Asked to explain, he replies, "check".
Seventeen seconds later the co-pilot warns "flight control," to which the captain responds "yeah".
Just after three minutes into the fight, and again later, the sound of pages being turned is picked up on the cockpit recording followed by the sound of the trim wheel - a manual override linked to the trim system controlled by MCAS.
The transcript suggests growing stress and more fragmented communications, coupled with confusion about which checklist to use.
The co-pilot searches increasingly frantically for an unreliable airspeed checklist - "Where is the?....no airspeed," and moments later, "Airspeed, airspeed" followed by more pages.
The captain asks a flight attendant to call the off-duty engineer who is travelling on the plane. The microphone picks up repeated chimes signalling calls between flight attendants.
The door opens and the captain is heard asking someone to look at what is happening with the computer, whose MCAS software - which the report confirms was not included in the manuals - continues to push the nose down using the plane’s trim system.
"OK, we are already gear up 5,000," advises the co-pilot. A sound similar to an altitude alert rings out. "Fly up," the co-pilot urges the captain.
Controllers ask the pilots whether the aircraft is descending, and the captain says "we have some problem". It is not clear whether he says this on the radio or to his colleague.
The co-pilot tells controllers they are flying manually due to the flight control problem.
Air traffic control instructs the pilots to prepare for landing at one of the runways.
The captain hands control of the plane to the co-pilot and contacts air control using the wrong flight number in a further sign of the gathering stress in the cockpit.
He warns air control that the altitude cannot be determined due to all the instruments showing different readings.
Controllers ask what altitude the pilots want, as the first officer is heard exclaiming that the aircraft is flying down.
The captain responds "FIVE THOU" (5,000 feet) and replies "It's OK" as the co-pilot again exclaims the jet is descending.
An excess speed warning sounds.
The co-pilot says "fly up".
Two computerised voice alerts - "TERRAIN, TERRAIN" followed by "SINK RATE" - blare out.
They are the final sounds included in the transcript before the 737 MAX hits the water at high speed, killing all 189 people on board.
Eleven minutes and 22 seconds after take-off, the recording stops.