Aircraft could be grounded for months, warns Ian Taylor
Investigators have identified “clear similarities” between last week’s Ethiopian Airlines disaster and an Indonesian air crash in October.
The Ethiopian Boeing 737 MAX crashed soon after take-off from Addis Ababa on March 10, killing all 157 people on board and triggering the aircraft’s worldwide grounding.
A Lion Air 737 MAX crashed soon after take-off from Jakarta on October 29, killing 189.
Flight-tracking data suggest both aircraft flew erratically, repeatedly climbing and descending before plunging to the ground.
A preliminary investigation of the Lion Air crash found problems with the aircraft’s anti-stall system which forced the nose of the aircraft down.
Pilots in the US reported similar problems. One pilot noted on an aviation whistle-blower site: “The nose pitched down after engaging auto pilot on departure.”
French air accident investigators have been examining flight-data and cockpit-voice recorders recovered from the Ethiopian Airlines crash since last week.
The 737 MAX has bigger, more fuel-efficient engines than previous models of the aircraft. Incorporating these meant moving the engines further forward on the wing, changing the aircraft’s centre of gravity.
Alongside these changes, Boeing introduced an auto-pilot feature or ‘manoeuvring characteristics augmentation system’ (MCAS) which pushes the nose of a climbing aircraft down if sensor data suggest the aircraft is in danger of stalling.
It was this system which appears to have kicked in during the Lion Air take off. The system can be switched off, but US pilot associations say Boeing failed to provide adequate information.
Denis Trajer, a spokesman for the American Airlines’ pilots’ union, said in November: “Information was not provided to us in our training or our manuals regarding this difference in systems.”
The US Federal Aviation Administration (FAA) admitted: “Boeing 737 Max training requirements do not address MCAS by name.” But it insisted: “The requirements do include the knowledge to deal with an MCAS event.”
Boeing said a software fix for the system “in response to erroneous sensor inputs” would be rolled out “within weeks”.
Both it and the FAA have been subject to growing criticism after the FAA was slow to ground the aircraft, reacting only after Chinese, Australian, UK and European authorities did so.
The investigation has become one of the biggest in aviation history, focused on the safety of the automated flight-control system and whether crews understood it.
But it has expanded into a criminal investigation in the US, with the Federal Bureau of Investigation involved and Justice Department prosecutors issuing multiple subpoenas in an inquiry, which began after the Lion Air crash, into the FAA certification of the 737 Max.
Investigators are reportedly examining the data that Boeing presented to the FAA.
Aviation safety consultant John Cox, former air safety chairman of the US Airline Pilots Association, told news agency Reuters the differences between the existing 737 and the 737 Max “were underplayed by Boeing” and said: “The operators didn’t realise the magnitude of the differences.”
Pilots of the older 737s were only required to take computer-based training in order to switch to flying the 737 Max.
Analysts suggest the crisis will cost Boeing billions in compensation, legal settlements, delivery delays and repair costs.
Boeing has delivered more than 350 737 MAXs and has orders for another 4,600.
A senior aviation analyst told Travel Weekly: “There is obviously an urgency to understanding what happened. [But] I don’t see it being resolved particularly quickly.
“It’s bound to have an impact and airlines will expect Boeing to compensate them. Boeing is producing 12 of the aircraft a week and can’t store them, so production will halt.
“There is going to have to be a modification and they need to understand the problem. Is it fixable? Will we see changes in orders for the aircraft? Will they be able to restore passenger confidence? They need to get to the bottom of it.”
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