The term PART OF AN AIRLINE FLEET can be summarized by two crossword solutions: JET and PLANE. A JET is a type of aircraft that is propelled by JET engines, which are powerful engines that take in a large amount of air and mix it with fuel to create thrust. Planes, on the other hand, are heavier-than-air aircraft that are powered by propellers or JET engines. Both jets and planes are commonly used by airlines as part of their fleets for transporting passengers and cargo.