Boeing aims to deliver up to 70 737 Max aircraft monthly to clear its backlog once the grounding is lifted, FlightGlobal has learned.

The manufacturer has not discussed publicly its plans for the profile or sequence of deliveries across its production line and the estimated 250-plus aircraft that have been built since deliveries were suspended on 13 March.

Boeing said very little about the 737 Max situation during the ISTAT EMEA conference in Berlin this week, but customer sources indicate once the grounding is lifted the manufacturer will focus efforts on delivering brand-new aircraft off the Renton production line, while simultaneously beginning the process to ship the stored undelivered aircraft. In parallel with this will be the programme supporting operators returning the more than 370 delivered-but-grounded Max aircraft to flight.

The Renton production line at is currently running at 42 737s per month and FlightGlobal understands that Boeing aims to begin delivering straight from the line at that rate while shipping a total of 60-70 aircraft a month with the balance being undelivered airframes currently in storage. The single highest monthly delivery total ever on the 737 series was 69 units in December last year.

Boeing says that as part of return-to-service planning, “we are working with our customers on the delivery sequence and being mindful of our ability to deploy those airplanes to customers for them to be able to bring them back up in their fleets in a very disciplined and safe way”.

Once deliveries recommence, Boeing aims to ramp output to the previously announced rate of 57 per month during 2020.

Speaking at Morgan Stanley conference on 11 September, the airframer’s chief executive Dennis Muilenburg explained how Boeing has been working to improve its production set-up during the grounding: “We’ve used this window over the last few months here, running at 42 a month to invest in stability of the production system and drive new quality systems and actions into the productivity of that system.

“And I think what you’re going to see on the backside here is a much better, much more efficient, much more effective production system overall. And our intent is to maintain the stability and health of that system as we think about the ramp up to 57.”

Operators of 737 Max tell FlightGlobal that completing all deliveries of the backlog of stored Max aircraft could take 12-18 months.

While there are a number of hurdles to be cleared before deliveries can resume, Boeing says it is currently planning for a return to service in the fourth quarter of 2019. But it is unclear how the return-to-flight approval will be adopted globally once the Federal Aviation Administration clears the aircraft to fly. Sources indicate that aligning all the regulatory authorities to allow a smooth clearance process is proving a challenge.