Why the Boeing 737 Max has been grounded again

FAA finds critical flaw that could further
delay troubled aircraft’s return to service

In Depth

On Wednesday, the US Federal Aviation Administration
(FAA) said it had identified a “potential risk” during
simulator testing of the 737 Max 8, but did not reveal any further
details, the BBC reports. The FAA has reportedly said that Boeing
must address the newly discovered issue before the aircraft can
return to service.

The 737 Max 8 has been grounded worldwide since March after the
second of the two fatal crashes involving the aircraft. The
downings of both Lion Air flight 610 and Ethiopian Airlines flight
302 are thought to have been caused by a new anti-stall system that
inadvertently reduced pilot control over the aircraft. 

“Boeing agrees with the FAA’s decision and request, and is
working on the required software to address the FAA’s request,”
Boeing said in a statement this week.

The Guardian reports that the new issue “means
Boeing will not conduct a certification test flight until 8 July at
the earliest”, and the FAA “will spend at least two to three weeks
reviewing the results before deciding whether to return the plane
to service”. It did not give a specific timeline.

Can Boeing get the 737 Max 8 back in the air and restore
confidence in its products?

Why is the plane grounded?

Boeing has been working on its stall-prevention system known as
MCAS since the Lion Air crash in Indonesia in October 2018 and the
one involving Ethiopian Airlines in March of this year.

The plane was grounded in the wake of the second crash.
Preliminary reports suggested that both incidents involved a
failure in Boeing’s newly-implemented Maneuvering Characteristics
Augmentation System (MCAS), an anti-stall system introduced on the
737 Max 8.

The system is designed to automatically bring the nose of the
aircraft down if the plane’s Angle of Attack (AOA) sensors detect
that the plane is pitched too high, thereby preventing a
potentially catastrophic stall in mid-air.

However, an investigation revealed that the aircraft’s AOA
sensor had fed faulty information to the MCAS, causing the plane’s
nose to automatically pitch down and defy pilot inputs, eventually
crashing. The combined death toll of the two crashes was 346.

The 737 Max was subsequently grounded by the world’s aviation
authorities in March until fixes could be made.

What is the new issue?

CNN reports that a series of simulator flights
to test new software developed by Boeing revealed a new flaw, but
no formal statement has been issued as to the nature of the
problem.

According to sources speaking to Reuters, an FAA pilot
simulation revealed that when the MCAS system was activated, it had
“taken longer than expected to recover the aircraft” manually.

“It was difficult for the test pilots to recover in a matter of
seconds,” the source said. “And if you can’t recover in a matter of
seconds, that’s an unreasonable risk.”

However, the BBC reports that other sources claim the problem
was “linked to the aircraft’s computing power and whether the
processor possessed enough capacity to keep up”.

Boeing said: “We are working closely with the FAA to safely
return the Max to service.”

What happens next?

“The FAA recently found a potential risk that Boeing must
mitigate,” the FAA said in the statement. “The FAA will lift the
aircraft’s prohibition order when we deem it is safe to do so.”

Deutsche Welle reports that Boeing was “in
complete agreement with the authorities on the matter and would
continue to seek a solution”.

The company said: “Boeing will not offer the 737 MAX for
certification by the FAA until we have satisfied all requirements
for certification of the MAX and its safe return to service.”

The BBC adds that if regulators are unsatisfied with the
software fix, the “microprocessor unit will have to be replaced and
the grounding may stretch on for months longer than previously
thought”.

As a precaution, American Airlines, United Airlines and
Southwest Airlines have all announced that they will not be using
the Max as part of their fleets until at least September.