The 737 Max has been grounded worldwide since mid-March following two fatal crashes involving the aircraft in just five months.

Lion Air flight 610 came down in the Java Sea shortly after taking off from Jakarta in October 2018. All 189 people onboard were killed. Then in March, Ethiopian Airlines flight 302 crashed en route to Nairobi from Addis Ababa, killing all 157 people onboard.

Initial investigations into both incidents found the same deep-seated flight control system to have been active when the two aircraft crashed.

Boeing continues to work on a software update, which it said on Monday (11 November) it hopes to have certified by the US Federal Aviation Administration during the fourth quarter.

“Boeing’s priority remains the safe return to service of the Max and supporting our airline customers through this challenging time,” said the company in a statement.

“We are working closely with the FAA and other regulatory authorities towards certification and safe return to commercial service, and we are taking the time to answer all of their questions.

“With the rigorous scrutiny being applied, we are confident the Max will be one of the safest airplanes ever to fly.”

Boeing said it “continued to target” FAA certification of its Max flight control software update “during this quarter”.

“Based on this schedule, it is possible the resumption of Max deliveries to airline customers could begin in December, after certification, when the FAA issues an airworthiness directive rescinding the grounding order,” said Boeing.

“In parallel, we are working towards final validation of updated training requirements, which must occur before the Max returns to commercial service, and which we now expect to begin in January.”

Boeing said it has completed the first of five “key milestones” it must achieve with the FAA before the Max can return to service – a multi-day simulator test assessing the effects of the new update.

Other steps will include evaluating pilot workloads; conducting certification flights using the new software; submitting final details to the FAA for certification; and then a second rigorous multi-day simulator test to assess any training requirements.

A number of European airlines will be hoping to return their 737 Max aircraft to service in the New Year, most notably Tui and Norwegian.

Ryanair, meanwhile, has been forced to scale back its summer 2020 expansion plans while it awaits the first of the 135 Maxs it has on order. Boss Michael O’Leary has, however, stressed Ryanair remains fully committed to its Max fleet.

British Airways owner IAG has also signed a letter of intent with regards to an order of some 200 Max aircraft.

Elsewhere, a number of US carriers have variously scheduled the Max for a return to scheduled service in March. Around of a third of the world’s Maxs were deployed on routes within North America when the Max was grounded.