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.

Boeing 737 MAXs were suddenly grounded while regulatory agencies decided if they should be allowed to return to the skies.

The 737-300, -400 and -500 aircraft have also some of the company’s most accident-prone designs. ... a 767 model, was forced to land without its landing gear in Istanbul, Turkey.

The 300 model upped capacity to 149, and the current roster of MAX models (though this suffix has since been removed from their names) has a total capacity of 172 (737-7), 210 (737-8), 220 (737-9 ...

A handful of the nearly 5,000 Boeing 737-800 aircraft produced have been involved in fatal crashes, but the jet is generally reliable and safe.