Boeing has reported “steady progress” in returning the troubled 737 Max to service but plans further workforce cuts in the face of a fourth consecutive quarterly loss.

The impact of the Covid pandemic has compounded the fallout from twin 737 Max crashes which left the new generation aircraft grounded since March 2019.

While the 737 Max is progressing through a “robust and comprehensive” certification process, Boeing saw commercial aircraft deliveries more than halve from 62 to 28 as overall sales plummeted from $8.2 billion to $3.6 billion.

The company expects to be employing about 130,000 staff by he end of 2021 – down 20% from 160,000 at the start of the year.

Boeing expects to “continue lowering overall staffing levels” as operations are re-sized “to align with market realities”.

Jobs will go through natural attrition as well as “voluntary and involuntary” workforce reductions.

Boeing posted a loss of $466 million in the three months to September 30 against a profit of more than $1.1 billion in the same period last year.

“Steady progress” towards the safe return to service of the 737 Max was reported in the three months, including “rigorous certification and validation flights” conducted by the US Federal Aviation Administration, Transport Canada and the European Union Aviation Safety Agency.

Civil aviation authorities from the US, Canada, Brazil and the EU, also conducted evaluations of updated crew training.

The 737 Max has now completed around 1,400 test and check flights and more than 3,000 flight hours.

Boeing continues to expect that US deliveries of the 737 Max could resume before the end of the year, although at reduced production rates.

The fleet has been grounded after 346 passengers and crew died in two separate crashes in Indonesia and Ethiopia.

Boeing president and chief executive Dave Calhoun told staff: “This quarter, we made important progress working closely with global regulators on 737 certification efforts.

“We also introduced a comprehensive Safety Management System (SMS), which incorporates the many lessons learned from the internal and external investigations surrounding the Max, and further drives our safety and first-time quality efforts across the enterprise.”

He said: “The global pandemic continued to add pressure to our business this quarter, and we’re aligning to this new reality by closely managing our liquidity and transforming our enterprise to be sharper, more resilient and more sustainable for the long term.

“Our diverse portfolio, including our government services, defence and space programmes, continues to provide some stability for us as we adapt and rebuild for the other side of the pandemic.

“Despite the near-term headwinds, we remain confident in our long term future and are focused on sustaining critical investments in our business and the meaningful actions we are taking to strengthen our safety culture, improve transparency and rebuild trust.”

The lower third quarter revenue recorded by Boeing’s commercial aircraft division reflected lower delivery volume primarily due to Covid-19 impacts as well as 787 “quality issues and associated re-work”.

Boeing also faced $590 million of “abnormal production costs” related to the 737 programme.

The firm reported a backlog of more than 4,300 aircraft valued at $313 billion.