The Boeing 737 MAX has long been the most important narrowbody aircraft put on the market by manufacturer Boeing, but the type has certainly faced its fair share of challenges. Originally designed as an upgraded version of the Boeing 737 Next Generation (one of the best-selling aircraft in history), the Boeing 737 MAX is one of the most capable aircraft on the market. The jet boasts impressive range and fuel efficiency, and it is one of the most affordable aircraft to operate in the skies today.