Boeing Co. Chief Executive Officer Dennis Muilenburg said he’s confident the grounded 737 Max aircraft will re-establish its position as a single-aisle workhorse for decades to come, as the company works through an in-depth review of the airframe design and its internal processes in the wake of two deadly crashes.

“The long-term, multi-decade strategy hasn’t changed,” Muilenburg said in an interview with Bloomberg Television in Paris on the first day of this year’s air show. Any all-out new aircraft in that space remains “a much more distant decision for the next couple decades,” the CEO said, adding that he’s confident in the Max’s product strategy.

The two crashes—one in October and another in March, both killing everyone on board—plunged Boeing into its deepest crisis in decades after regulators grounded the aircraft globally. The company is reviewing “every dimension of design and certification” and has identified some changes, Muilenburg said, with the hope of getting the plane back into service before the end of the year.

“We are going deeper than normal, and we encourage that,” Muilenburg said.

With more than 4,000 Max aircraft still in the order backlog, Boeing has no plan to accelerate the development of a successor, Muilenburg said, calling the Max a “very strong product line.” At the same time, the company is working on an all-new model that would sit between the single-aisle and wide-body aircraft, dubbed the New Mid-Market Airplane or NMA, with a plan for that model to begin service around 2025, Muilenburg said.

The NMA seeks to help Boeing arrest a march by rival Airbus SE in that space. The European company is readying an extended version of its A321 model, dubbed the A321XLR, that would bring extra range for trans-Atlantic routes. Airbus may introduce the model at the Paris expo this week, and has lined up customers including Air Lease Corp., according to people familiar with the matter.