Prior to the arrival of the L-1011s and the West Coast scheduled service network HA
operated DC-8s extensive military and civilian charter service.
Such charters continued with the arrival of the L-1011s so it certainly would not be odd to see HA
at the Imperial terminal.
Also keep in mind prior to the opening of TBIT in 1984, the Imperial Terminal was sort of low cost/charter facility with carriers like World, Trans America, Capital, Condor and LTU making home of the facility.