However, this also means that the wings are not optimized for the stretched Boeing 737-900. Among other things, this has the effect that the -900/ER has a lower optimal cruising altitude.

Usually, the Boeing 737-900ER needs a takeoff roll of about 2000 meters, or 6560 feet. That is the distance that the aircraft must travel to reach its lift-off speed and take off from the tarmac.

The impact was felt beyond just the Max, though because an earlier version of Boeing’s 737 — the 737-900 ER — also features this kind of door plug and required inspections.

Boeing launched the second generation, or Classic series of 737s, from 1984 to 1990, including the 737-300, 400, and 500. Boeing replaced the P&W engines with the more fuel-efficient CFM56 engines.

Key Takeaways: Boeing has been plagued by a series of high-profile crises involving the 737 Max. Existing 737 Max 9s can still fly, but the FAA is restricting Boeing's production. Investors ...