The Operational Factors That Influence A Jetliner’s Cruise Speed

Have you ever noticed varying cruise speeds during flight? Taking a quick look at the in-flight screen (on most long-haul aircraft), one can notice that the aircraft cruise speed typically varies between 480 mph and 550 mph (780 – 900 km/h) during flight. Why do aircraft not fly at the maximum cruise speed they are designed for? There are several factors that determine how the aircraft's cruise speed is set.