Questions remain after Boeing crashes

Manufacturer's relationship with US regulator challenged

Pallbearers carried 17 flag-draped coffins through the streets of Addis Ababa on Sunday to Holy Trinity Cathedral in the Ethiopian capital.

Crowds lined the streets to witness the procession of empty caskets.

Relatives were given bags of scorched earth from the crash site of Ethiopian Airlines Flight 302 in place of remains, which may take months to identify.

On March 10, all 157 people aboard the flight perished shortly after takeoff from Addis Ababa International Airport. They came from 35 countries.

Nearly two weeks later, the cause of the Boeing 737 Max 8 jetliner crash remains unknown. The disaster followed the crash in October of a Lion Air flight in Indonesia using the same type of plane, in which 189 people died. Both planes maneuvered erratically before crashing.

The crashes led 42 countries and regions to ground Boeing 737 Max jetliners. China was the first country to do so, and the United States was the last major nation to act, issuing its order four days after the crash in Ethiopia.

China, Boeing's largest market for the Max 8, has grounded all 96 of the jets operating in the country. The US is the second-largest market for the aircraft, with 72 of the planes in service, aviation and aerospace website FlightGlobal reported.

The crashes have also raised questions about the MAX 8's anti-stall device, pilot training, the procedure for certifying planes are safe for commercial use, and what some see as the cozy relationship between the US Federal Aviation Administration and Boeing, the world's leading aircraft manufacturer.

Boeing is cooperating with the investigation and is eager to determine the cause of the crashes, a message reinforced by a full-page advertisement in The Wall Street Journal on Wednesday signed by Boeing Chairman Dennis Muilenburg. At stake is the company's safety reputation and possibly 4,700 orders for MAX models and nine aircraft on back order－orders that will be sent out when an item is restocked－at about $120 million each.

Flight recorder data recovered from the planes show "clear similarities" between the two crashes, Ethiopian officials said.

Both planes flew erratically after experiencing difficulty with the Maneuvering Characteristics Augmentation System, the anti-stall device. An "angle of attack" sensor built into the aircraft measures the amount of lift produced by the wings. The device warns pilots when there is not enough lift, potentially stalling the plane, and then points the nose of the aircraft down to gain speed and remain airborne.

Some analysts believe that the pilots of the Ethiopian and Indonesian flights may not have known how to turn off the anti-stall device after it pointed the nose down, and if so, that may have been a factor in the crashes. The MAX 8, introduced in 2017, has been used by airlines in the US, Canada, Europe and China.

Bloomberg News reported that an off-duty pilot in the cockpit of a Lion Air Boeing 737 MAX 8 helped the crew disable the malfunctioning anti-stall system during flight after a frantic review of the plane's handbook offered no solution.

Next day, the same plane with a different crew crashed into the sea near Jakarta, the Indonesian capital. Reuters published a similar story, citing three people with knowledge of the discussion on the cockpit voice recorder of the doomed flight that has not yet been made public.

Analysts fault Boeing for not issuing explicit instructions on how to turn off the anti-stall device.