What does HAX stand for?

Hafnium Column Extractant - Nuclear energy (NRCH)

Hangar 5 Air Services Norway - FAA designator (FAAC)

Hawkline Boat Co., Westport, MA - Manufacturer code for watercraft hull identification number (USCG)

Helicopter Armored Experiment

Muskogee, OK - Location identifier - FAA (FAAL)

Southern Haida - Language code (ETLW)