text: Jet aircraft generally fly much faster than propeller-powered aircraft and at higher altitudes â `` as high as 10000 - . At these altitudes , jet engines achieve maximum efficiency over long distances .
simplified: Unlike propeller-powered aircraft , jet aircraft normally fly at altitudes as high as 10,000 to 15,000 meters , about 33,000 to 49000 f. At these altitudes , jet engines can achieve maximum efficiency over long distances .