Boeing says it is working on changes to the training and operation of its 737 Max plane that has suffered two major crashes within six months.

The U.S. plane maker is under huge pressure to satisfy regulators after the crash of Ethiopian Airlines Flight 302 on March 10, which killed all 157 people on board. Investigators have said there are "clear similarities" between that flight and a 737 Max crash in Indonesia in October that killed all 189 on board.

Boeing's vice president for commercial plane marketing, Randy Tinseth, told a Bank of America Merrill Lynch conference in London on Thursday that he expected the Federal Aviation Administration (FAA) to certify updates to the jet's flight control software, on board displays, flight manual and training.

"We have gone through steps such as working with it in a simulator, we flight tested the improvements and we are working with the FAA towards certification, and we believe that will happen in coming weeks," said Tinseth.

Boeing's chief salesman said data from the Ethiopian crash was still filtering through and it was still to draw full conclusions about the crash.

As investigations continue, the plane has been grounded by several jurisdictions around the world.

Crash investigators in both accidents are focusing on the plane's stall-prevention system, known as the maneuvering characteristics augmentation system. It has been reported that the system may have forced the plane's nose down following erroneous data from just one sensor.