Boeing’s chief executive has reiterated his expectation that the company will deliver the 737 Max’s updated software to the Federal Aviation Administration next month, which should enable regulators to lift the grounding by year-end.

“We are working through a software update,” CEO Dennis Muilenburg told investors on 7 August. “We still anticipate submitting that certification package to the FAA in the September timeframe… and are working toward a return to service of the Max in the fourth quarter.”

Muilenburg’s comments come nearly three weeks after the Chicago company disclosed that timeline, which led several airlines to shift further into the future the date on which they expect their Max will return to scheduled flying. Several airlines now have the aircraft returning in January.

Speaking during an investor conference hosted by Jefferies Financial Group on 7 August, Muilenburg stresses that approval remains in regulators’ hands.

But he sought to ensure investors that Boeing is doing all it can to achieve that timeline and to ensure that, when the grounding lifts, the aircraft returns to the skies as smoothly as possible.

In addition to tweaking the 737 Max’s flight control software, Boeing has been holding meetings globally with 737 Max customers and hosting simulator sessions with those customers, Muilenburg says.

The company has also been developing new training materials and completing “preservation” work intended the help ensure stored 737s are ready for quick deployment into airline flying.

Regulators initially grounded the 737 Max due to concerns about the role the aircraft’s maneuvering characteristics augmentation system (MCAS) played in two crashes. But in June the FAA discovered a data processing issue that required Boeing complete another rework.

That issue involved the flight computer’s data processing, an FAA official told FlightGlobal.