While this year saw the Boeing 737 family overtaken in popularity by the Airbus A320 series as the world’s best-selling line of narrowbody twinjet airliners, the single-aisle US-built aircraft remains a strong choice with operators all around the world. For the most part, such carriers use the jet on domestic and short-haul services, where theBoeing 737 offers operational flexibility and the ability to operate multiple round trips every day.