Density Altitude API

Aviation atmosphere maths as an API, computed locally and deterministically using the exact International Standard Atmosphere relations — the numbers a pilot, dispatcher or flight-planning tool needs before take-off, not a rough rule of thumb. The density-altitude endpoint turns the field elevation, altimeter setting and outside air temperature into the pressure altitude (elevation + (29.92 − setting) × 1000) and then the density altitude — the altitude the air actually feels like to the wings and engine — computed from the true ISA density ratio rather than the approximate 120-foot-per-degree rule, with the ISA temperature deviation: on a hot, high day the density altitude soars, robbing lift and thrust and lengthening the take-off roll, the classic mountain-airport hazard. The true-airspeed endpoint gives TAS from calibrated airspeed as CAS ÷ √(density ratio), so the navigator gets the real speed through the air that climbs above the indicated reading with altitude and temperature. The isa endpoint returns the standard-atmosphere temperature, pressure, pressure and density ratios and the speed of sound at any altitude in the troposphere — the reference every altimeter, performance chart and engine rating is built on. Everything is computed locally and deterministically, so it is instant and private. Ideal for flight-planning and EFB apps, drone and UAV tools, aviation weather dashboards, and aerospace-engineering utilities. Pure local computation — no key, no third-party service, instant. Troposphere (≤ 36,089 ft); incompressible TAS. 3 compute endpoints. For the speed of sound and Mach use a Mach-number API; for runway wind components a crosswind API.