English abbreviations from hacs to halo
- HACS (Hendersonville Area Computer Society)
- HACT (Helicopter Active Control Technology)
- HACU (Hispanic Association of Colleges and Universities)
- HAD (Halmstad Airport)
- HADA (Heavy Artillery Drone Armor)
- HAE (Lava Falls Heliport (FAA: AZ15) (Havasupai Airport))
- HAeBe ((celestial object) Herbig AeBe star, a type of pre-main sequence star with strong spectral emission lines)
- HAEMP (High Altitude Electromagnetic Pulse)
- HAEV (High Amplitude Electric Vibrator)
- HAF (Headquarters Air Force)
- HAFEZ (Hostile Aircraft Free Engagement Zone)
- HAG (Heavy Artillery Gun)
- HAGA (Houston Amateur Golf Association)
- HAH (Prince Said Ibrahim International Airport)
- HAHA (Humanists Atheists Heretics And Agnostics)
- HAHO (High Altitude High Opening)
- HAI (Human Awareness Institute)
- HAII (Hydro and Agro Informatics Institute)
- HAIN (Heavenly Angels In Need)
- HAIPE (High Assurance Internet Protocol Encryptor)
- HAIR (Hardcore Alternative Indie Rap)
- HAJ (Hannover Airport)
- HAK (Haikou Meilan International Airport)
- HAL (Hardware Abstraction Layer)
- HAL 9000 (Heuristic Algorithmic Computer 9000 (2001 A Space Odessy))
- HALCA ((telescope) Highly Advanced Laboratory for Communications and Astronomy, a satellite that is part of the VLBI Space Observatory Program, a Japanese radio astronomy project)
- HALE (High Altitude Long Endurance)
- HALO (High Altitude Low Opening, High Activity/Low Observable)