A remote pilot notices that flights at a new site consistently end sooner than at the usual location, with the same aircraft and payload. What is the most likely explanation?

Endurance is set by how much power the aircraft must produce to stay airborne against a fixed amount of stored energy, so anything that raises the power required shortens the flight. Three environmental factors do that, and a new site can change all three. Higher elevation and higher temperature both thin the air, so the propellers must spin faster to generate the same lift and the motors draw more current. Wind adds its own demand: a multirotor holding position in wind is continuously working against it, and one flying a survey pattern spends part of every leg into the wind. Cold is the fourth factor and works differently, reducing the battery's usable capacity rather than raising the power demanded. Same aircraft, same payload, shorter flights means the environment changed, and the pilot's response is to compute the actual conditions rather than carry over the endurance figures from the familiar site.

Higher elevation, higher temperature and wind all raise the power the aircraft must produce to stay airborne, which drains a fixed battery capacity faster.

Endurance depends on power required against available battery energy. Density altitude driven by elevation and temperature raises power demand, wind adds continuous work, and cold reduces usable battery capacity.

Thin Air, Wind, Cold. The first two make the aircraft work harder; the third gives it less to work with.

Note the mechanism difference: elevation, heat and wind raise power required; cold reduces available capacity. Both shorten the flight by different routes.

• •Suspecting battery degradation before checking the environment
• •Carrying endurance figures from one site to another
• •Conflating cold's effect on capacity with thin air's effect on power required