Boeing 737 MAX jets could be grounded for weeks as probe goes on

All Boeing737 Max 8 and 9 planes will remain grounded for weeks if not longer until a software upgrade can be tested and installed, U.S. lawmakers said on Thursday, as investigators in France prepare to begin analyzing the black boxes from the jet that crashed in Ethiopia.

Boeing said it had paused deliveries of its fastest-selling 737 Max aircraft built at its factory near Seattle but continues to produce its single-aisle jets at full speed while dealing with the worldwide fleet's grounding.

Investigators in France will seek clues into Sunday's deadly Ethiopian Airlines jetliner crash after take-off from the capital city Addis Ababa, which killed all 157 people on board from 35 nations in the second such calamity involving Boeing's same model of plane since October.

Possible links between the accidents have rocked the aviation industry, scared passengers, and left the world's biggest planemaker scrambling to prove the safety of a money-spinning model intended to be the standard for decades.

Men unload a case from a diplomatic car from the Ethiopian Embassy outside the headquarters of France's BEA air accident investigation agency in Le Bourget, north of Paris, March 14, 2019. /VCG Photo

After a briefing with U.S. aviation officials, U.S. Representative Rick Larsen said that the software upgrade would take a few weeks to complete, and installing it on all aircraft would take "at least through April." He said additional training would also have to take place.

Boeing has said it would roll out the software improvement "across the 737 Max fleet in the coming weeks."

Relatives of the dead stormed out of a meeting with Ethiopian Airlines on Thursday, decrying a lack of transparency, while others made the painful trip to the crash scene.

"I can't find you! Where are you?" said one Ethiopian woman, draped in traditional white mourning shawl, as she held a framed portrait of her brother in the charred and debris-strewn field.

A mourner cries as he looks at a photo of the co-pilot during a memorial at the crash site of Ethiopian Airlines Flight ET302 in Ejere, March 14, 2019. /VCG Photo

After an apparent tussle over where the investigation should be held, the flight data and cockpit voice recorders were handed over to France's Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA).

Technical analysis would begin on Friday and the first conclusions could take several days, the BEA said, posting a picture of the partly crumpled, orange-cased box.

Nations around the world, including U.S., have suspended the 371 Max models in operation, though airlines are largely coping by switching planes.

Nearly 5,000 Maxs are on order, meaning the financial implications are huge for the industry. Moody's rating agency said the fallout from the crash would not immediately affect Boeing's credit rating.

An American Airlines Boeing 737 Max 8 flight from Los Angeles lands at Reagan National Airport shortly after an announcement was made by the FAA in Washington, DC, that the planes were being grounded by the U.S. over safety concerns, March 13, 2019. /VCG Photo‍

"We continue to build 737 Max airplanes while assessing how the situation, including potential capacity constraints, will impact our production system," Boeing spokesman Chaz Bickers said.

Boeing would maintain its production rate of 52 aircraft per month, and its newest version, the Max, represents the lion's share, although Boeing declined to break out exact numbers.

The investigation of Sunday's crash has added urgency since the U.S. Federal Aviation Administration (FAA) on Wednesday grounded the 737 Max aircraft, citing satellite data and evidence from the scene that indicated some similarities and "the possibility of a shared cause" with October's crash in Indonesia that killed 189 people.

Though it maintains the planes are safe, Boeing has supported the FAA move. Its stock is down about 11 percent since the crash, wiping more than 26 billion U.S. dollars off its market value. It fell one percent on Thursday.