China, Indonesia, Ethiopian Airlines, Cayman Airways and South Africa-based Comair have temporarily grounded the Boeing 737 MAX 8 following a second crash of the type in less than six months.

An Ethiopian Airlines MAX 8, operating as ET302, crashed March 10 six minutes after departing Bole International Airport in Addis Ababa. All 157 passengers and crew were killed. The flight data recorder and cockpit data recorder have both been recovered, according to Ethiopian Airlines.

The MAX was already under scrutiny by Indonesian authorities following the crash of Lion Air JT610 on Oct. 29, 2018, in which all 189 people were killed. There has been no indication so far that the two crashes are linked.

Nevertheless, the Indonesian Directorate General of Civil Aviation (DGCA) late on March 11 said MAX 8s operated by Indonesian airlines would be grounded while additional inspections were carried out. Inspections are to begin as soon as March 12, the DGCA said.

Two Indonesian carriers operate MAX 8s. Lion Air has 10 in its fleet, and Garuda Indonesia has one, according to the DGCA notice. Both carriers have more on order.

The Indonesian DGCA stressed that Boeing and the FAA have said they will advise if any further steps become necessary.

Authorities in China had already moved to ground MAX 8s operated by their carriers, and Ethiopian Airlines and Cayman Airways have done the same with their MAX fleets. Other countries and airlines operating MAX 8s are taking a wait-and-see approach. For example, Singapore’s SilkAir said it was “monitoring the situation closely,” although there has been no change to its current operations—including scheduled MAX flights to China.

Cayman Airways pulled its two MAX 8s from service, with president and CEO Fabian Whorms saying, “While the cause of this sad loss is undetermined at this time, we stand by our commitment to putting the safety of our passengers and crew first by maintaining complete and undoubtable safe operations, and as such, we have taken the decision to suspend operations of both our new Boeing 737 MAX 8 aircraft, effective from Monday, March 11, 2019, until more information is received.”

Cayman’s second MAX was delivered just a week ago. Cayman has taken delivery of two MAX 8s—one in November and one last week.

Comair said March 11 it was pulling its single MAX 8 from service until more was known; that aircraft was delivered Feb. 27.

More than 70 MAX 8s are in service with Chinese airlines that include Air China, China Eastern, China Southern and Hainan Airlines. 

The Indonesia JT610 investigation is focusing on the roles of erroneous sensor data, a new flight-control law—the maneuvering characteristics augmentation system (MCAS) that was added to the 737 MAX family design to avoid stall—and how the Lion Air crew responded to what they faced. 

Information released by Indonesian investigators show JT610’s flight crew struggled to keep the MAX 8s nose up, apparently working to counter MCAS, which was automatically pushing the nose down in response to the erroneous data. A procedure that would override MCAS was apparently not followed by the JT610 crew, though it is unclear how much they understood about the failure sequence. The aircraft crashed into the Java Sea.

In the days after the Lion Air accident, Boeing issued messages to operators expanding on MCAS, and reiterating that the procedure for overriding automatic, repeated, nosedown inputs, remained unchanged from previous 737 models. FAA issued an emergency airworthiness directive requiring MAX operators to update their flight manuals with Boeing’s MCAS information. Boeing’s messages and the mandate did not require any new training or changes to the system.

As of Monday morning, no US airline had indicated it would pull MAX 8s from service. US operators include Alaska Airlines, American Airlines, Southwest Airlines and United Airlines. Worldwide, airlines have taken delivery of about 350 MAX 8s, and about 100 of them are affected by voluntary groundings.

However, US Association of Flight Attendants (AFA) president Sara Nelson has formally requested FAA to conduct an investigation into the 737 MAX.

“Crew and passengers are expressing concern about the 737 MAX 8 following a second crash, with similar characteristics to the Lion Air flight 610 [JT610] crash,” Nelson said in a March 11 statement. “While it is important that we not draw conclusions without all of the facts, in the wake of a second accident, regulators, manufacturers, and airlines must take steps to address concerns immediately. AFA is formally requesting the FAA conduct an investigation into the 737 MAX.”

Boeing, FAA and the NTSB are among those participating in both accident investigations.

Boeing has booked more than 5,100 orders for 737 MAX-family aircraft; the first MAX 8 entered service in May 2017.

Sean Broderick, sean.broderick@aviationweek.com

Adrian Schofield, Adrian.schofield@aviationweek.com