A popular new Boeing airliner has suffered two fatal crashes
in six months. Now several nations are grounding the surviving planes while the
FAA says the model is still airworthy.
The 737 Max 8 is the newest version of Boeing’s well-selling
737 series airliner with a longer range than the common domestic version. The
Max 8 entered service in May 2017 with its first commercial flight operated by Malindo
Air of Malaysia. About 18 months later, one of the new planes augured into
the Java Sea near Jakarta killing 189 passengers and crew. This week, a second
737 Max 8 crashed in Ethiopia under similar circumstances killing 157.
As a result of the two crashes, the Chinese Civil Aviation Administration grounded Max 8s operated by Chinese airlines. Chinese companies operate 97 of the airliners said CNN citing state media. The Chinese move was followed by Ethiopian Airways and Cayman Airways as they grounded their fleets. Indonesia also ordered its airlines to ground the planes. It is possible that the Chinese decision may have been influenced by the ongoing trade war with the United States and the knowledge that the move would reflect poorly on a major US export.
By Tuesday morning, other countries had decided to ground
the plane as well. Australia, Singapore, and several countries in Latin America
announced the grounding of their fleets, bring the total share of grounded jets
to about 40
percent of the global fleet.
“Here we have a brand-new aircraft that’s gone down twice in
a year. That rings alarm bells in the aviation industry
because that just doesn’t happen,” said Mary Schiavo, a CNN aviation analyst.
The first crash, on October 29, 2018, was a Max 8 operated as
Lion Air Flight 610 by an Indonesian airline. Shortly after takeoff, the crew
reported a flight control problem and announced a return to the airport. Before
they could do so, the plane crashed into the sea, killing all aboard, after a
12-minute flight. The preliminary
report on the accident blamed a new safety system designed to prevent the
aircraft from accidentally stalling.
The second crash, Ethiopian Airlines Flight 302, last Sunday
was remarkably similar
to the Lion Air crash. Although the information is still preliminary, the
Ethiopian flight also requested an immediate return after takeoff. Air traffic
controllers lost contact with Flight 302 six minutes after takeoff. Both planes
crashed in good weather and radar recorded erratic vertical speeds with
descents shortly after takeoff when the plane should have been climbing to a safe
altitude. The last indication showed Flight 302 descending at 2,000 feet per
minute, which is an extremely high descent rate at low altitude.
Despite the similarities and the fact that two US airlines,
American and Southwest, operate the Max 8, the FAA has not grounded the US
fleet. In a statement,
the FAA said, “External reports are drawing similarities between this accident
and the Lion Air Flight 610 accident on October 29, 2018. However, this
investigation has just begun and to date,
we have not been provided data to draw any conclusions or take any actions.”
Other observers are less cautious about a possible
connection. Former FAA Inspector David Soucie told CNN,
“I’ve never, ever done this. I’ve never said that
‘Hey, it’s unsafe to fly a particular model’ but in this case, I’m going to
have to go there. I just looked at the flight data of that aircraft. It’s
strikingly similar, same issues as with the Max [Lion] Air [crash]. So yeah, I
would watch for that airplane.”
The cause of the Lion Air crash appears to be a faulty
sensor in a new system that is designed to protect the airplane from a stall.
If the wing pitches too high, it loses lift and the airplane ceases flying. The
recovery technique for a stall is practiced by all pilots from students to airline
captains and consists of lowering the nose of the airplane and increasing power.
A stall typically occurs when the nose of the airplane is
raised too high or when the pilot is not using enough power. The safety system
in the Max 8 includes a pusher that
overrides pilot commands to lower the nose in the event of a stall. In the case
of Lion Air, an air
data sensor that measures the angle of the wing against the relative wind apparently
incorrectly signaled the aircraft’s flight control computers that the aircraft
was about to stall. The safety system pushed the nose down, but the plane’s
crew pulled up. What followed was 12 excruciating minutes of the airplane
trying to push the nose down and the crew frantically trying to pull it back up
to keep the airplane in the air.
In the wake of the crash, it was revealed that Boeing
initially omitted the new safety system from pilot training manuals for the
Max 8. The Lion Air pilots may not have known that the only way to override the
new system was to switch it off because older versions of the system in previous 737s could be overridden with pressure
on the control yoke. A few days after the Lion Air crash, Boeing released an operations
manual bulletin that required airlines to update their pilot manuals, but it
is not known whether the Ethiopian crew had received the updated information.
The problem with the 737 Max 8 seems to be partly a mechanical
problem with the air data sensors and partly a training problem with pilots who
do not apply the correct action when the anti-stall system activates erroneously.
Regardless of the exact cause, two crashes and the grounding of the fleet in
several countries is a public relations problem for Boeing. The Chinese
grounding is a particular problem since China is one of the largest customers
of the Max 8. If the airplane gets a bad
reputation, passengers may stay away from it, causing airlines to cancel