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Boeing will roll out a software upgrade for its grounded 737 Max aircraft in the coming weeks, following the Ethiopian Airlines crash that killed 157 people.

The US planemaker expects the US Federal Aviation Administration to approve design changes to the software "no later than April 2019".

Boeing began work on the upgrade after another 737 Max jet crashed in October.

Countries across the world have grounded Boeing 737 Max 8 and 9 jets.

An Ethiopian delegation has joined investigators in Paris tasked with uncovering the cause of the Boeing 737 Max crash on Sunday.

France's Bureau of Inquiry and Analysis for Civil Aviation Safety (BEA) received the flight data and cockpit voice recorders on Thursday.

The software Boeing plans to implement includes updates to the Maneuvering Characteristics Augmentation System.

This is the 737 Max's automatic anti-stalling system which is designed to keep the plane from stalling.

It stops the aircraft from pointing upwards at too high an angle, where it could lose its lift.

However, there have been incidents of pilots reporting that the system tipped the aircraft's nose downwards within minutes of take-off, forcing them to step in to stop the plane from dropping.

The FAA has said that the Boeing 737 will not fly until a software update can be tested and installed.

The BEA has taken charge of the Ethiopian Airlines aircraft's black boxes, but a spokesman said the first analyses could take between half a day and several days, depending on the boxes' condition.