Cruise ( aeronautics ) - Wikipedia Cruise ( aeronautics ) A four - engined Qantas Boeing 747 - 400 jet in cruise Cruise is a flight phase that occurs when the aircraft levels after a climb to a set altitude and before it begins to descend. Cruising usually consumes the majority of a flight, and it may include changes in heading ( direction of flight ) at a constant airspeed and altitude. For most passenger aircraft, the cruise phase consumes most of the aircraft 's fuel. This lightens the aircraft and raises the optimum altitude for fuel economy. For traffic control reasons it is usually necessary for an aircraft to stay at the cleared flight level. On long - haul flights, the pilot may ask air traffic control to climb from one flight level to a higher one, in a maneuver known as step climb. Cruise speed Commercial or passenger aircraft are usually designed for optimum performance at their cruise speed ( V ). Combustion engines have an optimum efficiency level for fuel consumption and power output. Generally, piston engines are most efficient between idle speed and 25 % short of full throttle. With aircraft, other factors affecting optimum cruise altitude include payload, center of gravity, air temperature, humidity, and speed. This altitude is usually where the higher ground speeds, the increase in aerodynamic drag power, and the decrease in engine thrust and efficiency at higher altitudes are balanced. The typical cruising airspeed for a long - distance commercial passenger aircraft is approximately 475 -- 500 knots ( 878 -- 926 km / h ; 546 -- 575 mph ). See also Supercruise Takeoff Visual flight rules References Jump up ^ `` Glossary ''. CAST / ICAO Common Taxonomy Team. Retrieved 2016 - 06 - 19. Jump up ^ Cruising speed definition Jump up ^ Idle speed mentioned as most efficient in some cases, up to 75 % of full throttle ; or 3600 rpm for gasoline engines Flight phases Main phases Taxiing Takeoff Climb Cruise Descent Landing Related topics Takeoff and landing types Holding Rotation Step climb Top of climb Loiter Top of descent Final approach Go - around This article about aviation is a stub. You can help Wikipedia by expanding it. Retrieved from `` https://en.wikipedia.org/w/index.php?title=Cruise_(aeronautics)&oldid=842499433 '' Categories : Flight phases Aviation stubs Talk About Wikipedia Български Català Deutsch فارسی Français Italiano Bahasa Melayu Nederlands 日本 語 Português Русский Svenska Українська 中文 6 more Edit links This page was last edited on 22 May 2018, at 21 : 14. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: what is the average speed of passenger airplane
Answer: approximately 475–500 knots (878–926 km/h; 546–575 mph)