WASHINGTON • Boeing confirmed late on Monday that it will deploy a software upgrade to the 737 Max, a few hours after the US Federal Aviation Administration (FAA) said it would mandate "design changes" in the aircraft by next month.
Boeing did not reference Sunday's Ethiopian Airlines crash in connection to the software upgrade, but it expressed the company's condolences to the relatives of the 157 people who died.
The company said that in the aftermath of last October's Lion Air Flight 610 crash, it has for several months "been developing a flight control software enhancement for the 737 Max, designed to make an already safe aircraft even safer".
The software upgrade "will be deployed across the 737 Max fleet in the coming weeks", it said.
The FAA said on Monday that it would order Boeing to modify its 737 Max 8 aircraft, including having anti-stalling software and manoeuvring system updates, after two of the planes crashed in five months.
The changes will also apply to the Max 9 aircraft.
The FAA told international civil aviation authorities that it "anticipates mandating these design changes... no later than April".
The statement signals that US regulators have no immediate intention of grounding the 737 Max 8, breaking with a decision by China and others to tell their airlines to suspend the use of the aircraft after the latest crash.
Boeing is also set to update its training requirements and flight crew manuals to reflect the changes.
The FAA has notified other global civil aviation authorities that it may soon share safety information concerning Boeing's 737 Max 8, the statement said.
Nevertheless, US aviation regulators underlined their confidence in the safety of the 737 Max jetliner with a global notice of "continued airworthiness".
The FAA said there is no conclusive evidence so far to link the loss of the Ethiopian Airlines 737 Max 8 and the fatal Lion Air disaster involving the same jet model in October last year.
"External reports are drawing similarities between this accident and the Lion Air Flight 610 accident on Oct 29, 2018," the FAA said. "However, this investigation has just begun and to date we have not been provided data to draw any conclusions or take any actions."
The plane-maker echoed the FAA's statement, saying that it stood by the aircraft, which is a revamped version of its workhorse single-aisle jet.
According to Bloomberg Intelligence analyst George Ferguson, the 737 family is on pace to generate about US$30 billion (S$41 billion) in annual revenue, and about a third of the company's operating profit.
Said Boeing chief executive Dennis Muilenburg, in a message to employees shortly after the FAA released its statement: "We are confident in the safety of the 737 Max and in the work of the men and women who design and build it.
"Since its certification and entry into service, the Max family has completed hundreds of thousands of flights safely."
Mr Muilenburg also reminded employees that all requests on the topic "must flow through the proper channels" as investigators probe the crash.
"There are still many facts to learn and work to be done," he said.
"Speculating about the cause of the accident or discussing it without all the necessary facts is not appropriate and could compromise the integrity of the investigation."
Despite misgivings expressed by some labour unions, US carriers such as Southwest Airlines, American Airlines and United continue to fly the 737 Max.
Ms Lori Bassani, president of the Association of Professional Flight Attendants, which represents employees at American Airlines, said: "We do have a few flight attendants who are indicating they are afraid to fly the 737 Max."
No attendants have refused to fly on the plane so far.
More than 100 of the Boeing planes have been grounded outside the United States, about one-third of the global Max fleet.
REUTERS, BLOOMBERG, AGENCE FRANCE PRESSE