The strength of gravity at the Earth's surface is not constant, but varies from place to place by as much as a few percent:
(Image by NASA.)
As a result, an identically-loaded aircraft weighs less in (for instance) southern India, Uyghurstan, the eastern Caribbean, or the Hudson Bay area than it does in (for instance) Indonesia, Greenland, Liberia, or the Russian Far East, which should (in theory, at least) affect its operations in several different ways:1
- An aircraft in a lower-gravity region won't need to generate as much lift in order to become, or remain, airborne, allowing it to take off and land at slightly lower speeds, to climb slightly more steeply, and to cruise at slightly higher altitudes.
- An aircraft in a lower-gravity region can be loaded slightly fuller without exceeding its maximum allowable takeoff weight (potentially giving it a range advantage over an aircraft launched from a higher-gravity region, if the extra capacity is used to carry more fuel), and can land slightly fuller without exceeding its maximum landing weight and risking structural damage.
- An aircraft landing in a lower-gravity region will have less weight on its wheels, slightly reducing the maximum braking force available from the wheelbrakes (which might well cancel out the landing-weight advantage mentioned in the previous bulletpoint), and, thus, requiring a slightly longer runway.
Do aircraft performance figures and calculations include corrections for local and/or regional variations in the strength of gravity, or are these variations simply considered too small to bother accounting with?
1: This is by no means meant to be an exhaustive list.