Fuel
Aircraft manufacturers are responsible for generating flight performance data which flight planners use to estimate fuel needs for a particular flight. The fuel burn rate is based on specific throttle settings for climbing and cruising. The planner uses the projected weather and aircraft weight as inputs to the flight performance data to estimate the necessary fuel to reach the destination. The fuel burn is usually given as the weight of the fuel (usually pounds or kilograms) instead of the volume (such as gallons or litres) because aircraft weight is critical.
In addition to standard fuel needs, some organizations require that a flight plan include reserve fuel if certain conditions are met. For example, an over-water flight of longer than a specific duration may require the flight plan to include reserve fuel. The reserve fuel may be planned as extra which is left over on the aircraft at the destination, or it may be assumed to be burned during flight (perhaps due to unaccounted for differences between the actual aircraft and the flight performance data).
In case of an in-flight emergency it may be necessary to determine whether it is quicker to divert to the alternate airfield or continue to the destination. This can be calculated according to the formula (known as the Vir Narain formula) as follows:
where C is the distance from the Critical Point (equitime point) to the destination, D the distance between the destination and the alternate airfield, O is the groundspeed, A is the airspeed, θ = Φ +/- d (where Φ is the angle between the track to the destination and the track from the destination to the alternate airfield), and d is the drift (plus when the drift and the alternate airfield are on the opposite sides of the track, and minus when they are on the same side).
Read more about this topic: Flight Plan
Famous quotes containing the word fuel:
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—Alexander Theroux (b. 1940)
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—Gwendolyn Brooks (b. 1917)
“It is now many years that men have resorted to the forest for fuel and the materials of the arts: the New Englander and the New Hollander, the Parisian and the Celt, the farmer and Robin Hood, Goody Blake and Harry Gill; in most parts of the world, the prince and the peasant, the scholar and the savage, equally require still a few sticks from the forest to warm them and cook their food. Neither could I do without them.”
—Henry David Thoreau (1817–1862)