Various methods of standard, or stored, flight planning are in use throughout the world and have some degree of success, but on occasions they are too rigid to accommodate changes to routes or in weather patterns. A standard plan should eliminate the individual differences between manually computed flight plans by two pilots for the same route in identical aircraft. It should be in real time, flexible enough to allow route changes by ground control and capable of taking advantage of fuel-saving tail-wind components. All four requirements are inextricably linked.