Originally Posted by travelsensei
These 'guesses' are from insiders at both airlines...it would still be nice to know for sure...
HP - America West chose this designator because of their major presence/hub in Phoenix (therefore, HP means 'hub Phoenix')
Completely wrong.
When America West first began service the IATA code AW was already taken. So America West purchased the operating certificate from Hawaiian Pacific, and was then assigned the code HP.