"Should our estimate of the anticipated return to service change, we might need to consider possible further rate reductions, or other options including a temporary shutdown of the MAX production," Muilenburg said in the teleconference on Wednesday.
However, Muilenburg said they expect to maintain the current monthly production rate of 42 deliveries per month and by 2020 increase it to 57.
Global aviation authorities grounded the 737 MAX following two crashes - in Indonesia and Ethiopia - that killed a total of 346 passengers and crew because of a software glitch that prevented pilots from turning off a defective autopilot system that forced planes into the ground shortly after takeoff.
Boeing attempts to repair the defects are taking longer than expected, and the company does not expect the planes to be declared safe to fly by the US and other regulators until November at the earliest.