A commonly used cruising altitude for jet powered airliners is 30,000 feet. During flight, pilots receive weather reports from the ground too as from other pilots in the area. They will often request a change in cruising altitude from air traffic control to avoid building thunderstorms or to avoid reports of clear air turbulence. Another consideration is the length of the flight.
A cruising altitude is the altitude at which an aeroplane spends most of its flight. This is the altitude at which it levels elsewhere after completing its distant climb after takeoff. This altitude allows the aircraft to fly aggrandized efficiently, to avoid pathetic weather and to stay fair of other aircraft. Depending upon the length of the flight and the type of aircraft, cruising altitudes typically vary between around 25,000 feet and 40,000 feet. For longer flights, it is not scarce for an airliner to alter cruising altitudes indefinite times, gradually working its form to higher levels as it burns off fuel and becomes lighter in weight. This growth is manifest as a development climb. For every flight, there is an optimum cruising altitude that is calculated based on weight. The process climb system is used to garner the aircraft at the optimum altitude as the plane's weight decreases over eternity. Altitudes in this radius are measured in feet above sea equivalent with a barometric altimeter establish at 29.92 inches of mercury.
The air in the Area's atmosphere becomes consistently thinner as altitude increases. This is why a barometer can be used To gauge changes in altitude. As the air becomes thinner, it creates less resistence to objects flying completed it. Since, less thrust is needed to procedure the aircraft forward at a disposed velocity. As a corollary, airplanes can fly aggrandized efficiently at higher altitudes. On the other hand, there are limits to how gigantic an aeroplane can fly. Provided the aircraft is extremely ponderous, aggrandized fuel is required to lift the aircraft higher. Secondly, as the air gets thinner with altitude, the rapidity of sound decreases with increases in altitude. In that most airliners are not designed to fly at or above the rapidity of sound, they eventually stretch a site at which their rapidity is resident by the rapidity of sound. At the alike period, an aircraft must keep a undeniable airspeed in succession for the wings to design lift. This is called the stall precipitation. In the thinner air at great altitudes, the plane must fly faster and faster in plan to carry on above the stall precipitation. Inasmuch as, whether an aeroplane climbs very high rise, it can be reformed trapped between its increasing stall speed and the decreasing velocity of sound. Pilots consult to this trap as "Casket corner." As a close of these dangers, cruising altitudes on conventional airliners are strictly regional and scarcely exceed 40,000 feet.
Cruising altitudes are referred to as in aviation vernacular as "flight levels" and are identified by dividing the altitude by 100. Thus, an altitude of 30,000 feet is referred to as "flight even 300," and an altitude of 35,000 feet is referred to as "flight level 350." In order to reduce the danger of mid-air collisions, cruising altitude assignments are based on the compass heading that the aircraft is flying. If an airplane is flying a heading between 360 degrees and 179 degrees, then it will fly at an odd-numbered flight level. If an airplane is flying a heading between 180 degrees and 359 degrees, it will fly at an even-numbered flight level. Thus, an airliner flying due east (090 degrees) would fly at an odd numbered flight level such as flight level 310 or flight level 330, while an airplane flying in the opposite direction (270 degrees) would choose an even-numbered flight level such as 300 or 320. Thus, even if the two planes were flying directly toward each other along the same course, they would be vertically separated by at least 1,000 feet.
In aviation parlance, altitudes are normally defined Towards feet above sea level. Since the ground rises and dips constantly, it would be impractical to use altitude above the ground as a general reference. However, pilots must nevertheless be constantly aware of the terrain height where they are flying. Twenty thousand feet offers plenty of ground clearance when flying over southern Florida, but the same altitude would put a plane in a very precarious position in the Himalayas. Terrain heights are marked on aeronautical charts that pilots use. Moreover, many aircraft are equipped with radar altimeters, which measure vertical separation with the ground.
Weather is another consideration that can affect the cruising altitude of an airliner. Hence, one recurrently hears this altitude referred to in informal debate or on television. Nevertheless, airliners de facto cruise at a change of altitudes. There are indefinite factors that arbitrate the cruising altitudes at which an airliner flies.