Flight Level

A flight level (FL) is a standard nominal altitude of an aircraft, in hundreds of feet. This altitude is calculated from the International standard pressure datum of 1013.25 hPa (29.92 inHg), the average sea-level pressure, and therefore is not necessarily the same as the aircraft's true altitude either above mean sea level or above ground level.

Read more about Flight Level:  Background, Transition Altitude, Quadrantal Rule, Semicircular/Hemispheric Rule, Reduced Vertical Separation Minima, Metric Flight Levels, Flight Levels in Russian Federation

Famous quotes containing the words flight and/or level:

    In all her products, Nature only develops her simplest germs. One would say that it was no great stretch of invention to create birds. The hawk which now takes his flight over the top of the wood was at first, perchance, only a leaf which fluttered in its aisles. From rustling leaves she came in the course of ages to the loftier flight and clear carol of the bird.
    Henry David Thoreau (1817–1862)

    Preschoolers sound much brighter and more knowledgeable than they really are, which is why so many parents and grandparents are so sure their progeny are gifted and super-bright. Because children’s questions sound so mature and sophisticated, we are tempted to answer them at a level of abstraction far beyond the child’s level of comprehension. That is a temptation we should resist.
    David Elkind (20th century)