Boeing is studying if it can drive production at the Renton factory building 737 airliners even higher, company CEO Dennis Muilenburg said in a third-quarter earnings call with the media Wednesday.

Boeing says it has successfully ramped up 737 production in recent months to 47 per month. It's scheduled to go to 52 jets per month in 2018 and 57 per month in 2019.

All of those increases have been previously reported. But beyond that? Boeing executives have said in past years that the single Renton factory could crank out as many as 63 airplanes per month.

Company executives said there is increasing upward pressure to build more as the so-called “single-aisle” market continues to have the highest demand. Single aisles refer to airplanes with one aisle with seats on either side -- unlike a 787 or other larger jets with two aisles. The single-aisle market includes the Airbus 320 which is also experiencing high demand.

Muilenburg and Chief Financial Officer Greg Smith said Boeing’s 737 order book -- or production skyline in industry speak -- is sold out through the end of the decade.

Muilenburg says the company is looking at efficiencies in the factory which could allow for more production. Those efficiencies have come from both mechanics who assemble the jets to engineers who design not only the airplane but the production system. The kinds of numbers the plant is already reaching would have been considered unthinkable not even a decade ago, much less going beyond a rate of 57 airplanes each month.

When asked if the development of a new airplane called the NMA, or new “New Medium Market or Mid-sized Airplane” would dampen demand for the longest 737s with the most seating capacity, Muilenburg says "no" -- that the two aircraft types would be complimentary. Muilenburg says Boeing is still studying the NMA and has not made a go or no-go decision, but if built, the plane would enter service with the airlines in 2024 or 2025. The NMA would fill a gap between the larger 737s and the Everett-built 787.