The first conclusions from the technical analysis on two black boxes from the Boeing 737 Max airplane that crashed in Ethiopia could take several days, officials said, as regulators around the world awaited word on whether it's safe to resume flying the jets.

More than 40 countries — including the U.S., Canada, India, China and Russia — have grounded the planes or refused to let them into their airspace.

A spokesperson for France's BEA air accident investigation agency said the flight data and cockpit voice recorders have been delivered. Investigators in will now begin seeking clues into what caused the disaster that's angered scores of mourning families.

Data in the boxes is critical to finding out what caused the new aircraft to plunge to the ground shortly after taking off from Addis Ababa on Sunday, killing all 157 people aboard.

It was the second crash involving a 737 Max in less than five months.

Big financial implications for industry

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

On Thursday afternoon, Boeing announced it would pause deliveries of 737 Max jetliners. Nearly 5,000 Maxes are on order from the company, meaning potentially huge financial implications for the industry.

A case containing the black boxes from the crashed Ethiopian Airlines Boeing 737 Max 8 was delivered to the headquarters of France's BEA air accident investigation agency in Le Bourget, north of Paris, on Thursday. (Philippe Wojazer/Reuters)

Boeing, which maintained its planes were safe to fly, said in a statement that it supported the U.S. regulators who grounded the plane.

"Boeing has determined — out of an abundance of caution and in order to reassure the flying public of the aircraft's safety — to recommend to the FAA the temporary suspension of operations of the entire global fleet of 371 737 Max aircraft."

The FAA, the National Transportation Safety Board, the Ethiopian civil aviation authority and Boeing have been investigating the crash at the site, some 60 kilometres outside the Ethiopian capital.

'We saw where he died and touched the earth'

On Thursday, some relatives of the dead stormed out of a meeting with Ethiopian Airlines, decrying a lack of transparency, while others made the painful trip to the arid farmland where the passenger jet crashed.

"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.

Investigators with the U.S. National Transportation and Safety Board look over debris at the crash site. (Jemal Countess/Getty Images) "We saw where he died and touched the earth," said Sultan Al-Mutairi, who had come from Riyadh to mourn his brother, Saad, who ran a recruitment agency in Nairobi and perished in the crash.

Experts say it could take weeks or months to identify the victims, as their remains were scattered, charred and in fragments due to the impact of the crash and ensuing fire.

Frustration is growing among the families of victims of the crash who are in Addis Ababa, with many of them asking Ethiopian Airlines for greater transparency.

Airline officials said they have opened a call-in centre that is available 18 hours a day to respond to questions by family members. But angry family left the meeting at a hotel in Addis Ababa, saying there were not getting enough answers.

Same cause as Lion Air crash?

The weekend crash is the second since October that occurred just after takeoff. In October, a Lion Air plane crashed in Indonesia.

Fresh information from the wreckage in Ethiopia and newly refined data about the plane's flight path indicated some similarities between the two disasters "that warrant further investigation of the possibility of a shared cause," the FAA said in a statement.

The cause of the Indonesian crash is still being investigated. A November preliminary report, before the retrieval of the cockpit voice recorder, focused on maintenance and training and the response of a Boeing anti-stall system to a recently replaced sensor, but gave no reason for the crash.

The pilot of that aircraft had reported internal control problems and received permission to return, before the plane came down and burst into a fireball on arid farmland.

Pilots on at least two U.S. flights have reported an automated system seemed to cause their Max 8 planes to tilt down suddenly.

The 737 is the most popular commercial jetliner of all time, and Boeing has seen strong demand for the latest iteration, the 737 Max. (David Ryder/Bloomberg) The pilots said the tilt occurred soon after they engaged autopilot. In both cases, they recovered quickly after disconnecting the autopilot.

U.S. lawmakers said after a briefing with the acting head of the FAA on Thursday that Max 8 and 9 planes will remain grounded for "weeks" at a minimum, until a software upgrade could be tested and installed in all of the planes.

FAA administrator Dan Elwell told reporters on Wednesday the software update will be ready within a couple of months. But that may not be enough to allow the planes to be ungrounded depending on the findings.

Rep. Rick Larsen, from Washington state, said after the briefing the software upgrade would take a few weeks to complete and installing on all aircraft would take "at least through April."

He said additional training would also have to take place.

Deliveries of Boeing's bestselling 737 Max jets were effectively frozen, though production continued, industry sources said.

With the uncertainty hanging over the 737 Max, a French presidential source said European plane-maker Airbus and Ethiopian Airlines are discussing a possible new contract as part of the airline's fleet overhaul.

The official said French President Emmanuel Macron and Ethiopian Prime Minister Abiy Ahmed had spoken about a possible new contract during Macron's visit to Addis Ababa this week.

Airlines operating the 737 Max jets that have been delivered since its 2017 debut said they had cancelled some of their flights and rearranged schedules to use other jets in their fleets.

"Our goal is to operate our schedule with every available aircraft in our fleet to meet our customers' expectations during the busy spring travel season," said U.S. carrier Southwest Airlines Co., the world's biggest operator of the plane.