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I am very new to aviation and trying to understand how to calculate the actual range of an aircraft given real world wind conditions. I understand from this related question that you need 30 minutes of reserve and that tailwind and headwind direction will obviously impact your range. I've also heard that the altitude you fly at can impact your range because higher air is thinner and allows you to travel faster. I also would assume that the aircraft load would impact range. So my question is:

Given the theoretical range of an aircraft (i.e. from specs published at this site) how do you calculate how far the aircraft can actually travel at a given altitude, with a given load, and with current wind conditions?

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  • $\begingroup$ See Ground Studies for Pilots, Flight Planning by Peter J. Swatton, Chapter 5, General Fuel Requirements - p. 110 and 6, 7, or 8 depending on the type of engines. $\endgroup$ – mins Jun 6 '15 at 16:20
  • $\begingroup$ The "theoretical range of an aircraft" has a lot of "it depends" factors that are assumed in computing it, and how far you can "actually travel" has a similar number of factors that go in -- some are current conditions, others are things like planned altitude, how much reserves are required (driven by what rules you're operating under), etc. Getting from the theoretical number to the real one would require reverse engineering all the assumptions from what they planned on, back out to what you're actually doing. Best bet, as Peter Kampf says, is to do the computations from source documents. $\endgroup$ – Ralph J Jun 6 '15 at 17:44
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The best answer: Use the charts in the respective Pilot's Operating Handbook (POH). There you should find correction factors for the parameters which influence aircraft range

  • Fuel on board: The more, the better. But note that doubling fuel will not double range.
  • Take-off mass: If you take no payload, the aircraft will produce less induced drag and reach a slightly higher range. See the chart below for an example.
  • Wind enroute. Follow the link; the wind component parallel to your flight direction will change the range by the product of wind speed times flight time.
  • Cruise altitude: This depends on the type of engines, jets benefit more from altitude than propeller aircraft.
  • Temperature

Generally, there should be a chart like this:

This is a typical payload-range diagram with the three distinct points: Maximum payload, maximum fuel and transfer range with no payload.

It plots the maximum achievable range over the aircraft's payload and assumes that the tanks are filled such that the flight starts with the maximum take-off mass. The chart should also have an explanation that clarifies which altitude and which thrust setting were used.

Or you use approximations like Breguet's range equation, which require detailed knowledge of the aircrafts L/D and the engine's fuel consumption. That will be the weakest point of any range calculation: Sufficient data how changes in the aforementioned parameters affect the result.

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