The original "long" 737 variant was 30.5m; the 737 MAX 10 is 43.8m long. Many of the problems with the 737 airframe are rooted in this growth, along with it bei

The original "long" 737 variant was 30.5m; the 737 MAX 10 is 43.8m long. Many of the problems with the 737 airframe are rooted in this growth, along with it being originally designed as a regional jet with needed compromises (being low to ease airstairs, which caused problems with engines since the first re-engining with the Classic series). Note that Boeing was trying to sell airlines on a clean-sheet aircraft when Airbus launched the A320neo, and _quickly_ started gaining customers, including those that had been loyal to Boeing for decades. Boeing needed something to counter the A320neo, hence the MAX had to happen—and soon.