A Boeing 737 Max takes part in flyng display during the 52nd Paris Air Show at Le Bourget Airport near Paris, France, June 22, 2017. (REUTERS Photo)

SAN FRANCISCO, March 11 (Xinhua) -- Top U.S. aircraft manufacturer Boeing Company said Monday that it is planning to make a safety upgrade to software that is to be deployed across the fleet in the coming weeks.

Boeing said it is working with the U.S. Federal Aviation Administration (FAA) to develop the software enhancement, which the FAA hoped to mandate with an Airworthiness Directive no later than April.

The Boeing announcement came one day after an aircraft of Ethiopian Airlines crashed Sunday morning, killing all 157 passengers and crew members on board a 737 MAX 8 plane.

The plane crash was the second fatal incident involving the same model in five months.

Another Boeing 737 MAX 8, flown by Indonesia's Lion Air, crashed soon after takeoff from Jakarta in October last year, killing 189 people.

Boeing did not make direct reference to Sunday's air crash of Ethiopian Airlines Flight 302 while announcing the software upgrade plan on Monday, but it offered its "deepest condolences to those who lost loved ones" on Ethiopian Airlines Flight 302.

The aircraft giant said a Boeing technical team is at the crash site to provide technical assistance to the local authorities.

Boeing said it has been developing a flight control software enhancement for the 737 MAX for the past several months in the aftermath of the Lion Air Flight 610 tragedy.

Despite Sunday's air crash in Ethiopia, Boeing said that the 737 MAX is "a safe airplane that was designed, built and supported" by its skilled employees.