- h Hour(s).
- handed Rotating in opposite directions.
- hardened Protected as far as possible against nuclear explosion.
- hardpoint Reinforced part of aircraft to which external load can be attached, for example weapon or tank pylon.
- HDU Hose-drum unit.
- head-down display On the cockpit instrument panel (as distinct from a HUD).
- head-level display Immediately below HUD.
- helicopter Rotary-wing aircraft both lifted and propelled by one or more power-driven rotors turning about substantially vertical axes.
- HF High frequency.
- HIFR Helicopter in-flight refuelling.
- HIRF High-intensity radiated field(s).
- HMD Helmet-mounted display; hence HMS = sight.
- HOCAC Hands on cyclic and collective.
- homebuilt Aircraft built/assembled from plans or kits.
- hot-and-high Adverse combination of airfield height and high ambient temperature, which lengthens required take-off distance.
- HOTAS Hands on throttle and stick.
- hot refuelling Replenishment of fuel while engine(s) running.
- hovering ceiling Ceiling of helicopter (corresponding to air density at which maximum rate of climb is zero), either IGE or OGE.
- HP High pressure (HPC, compressor; HPT, turbine).
- hp Horesepower, non-SI unit of power.
- HSI Horizontal situation indicator.
- HUD Head-up display (bright numbers and symbols projected on pilot's aiming sight glass and focused on infinity so that pilot can simultaneously read display and look ahead). The term is increasingly rendered in the USA as "heads up", which is incorrect.
- Hz Hertz, cycles per second.
