Stationair8. Ansett operated the DC9 on a ad-hoc basis BNE-ISA-BNE usually usung Flight Numbers 1692/1691. Most departures from ISA were at approx. 0400Lt to enable a resonable payload to be uplifted. From memory the main payload consideration was the possibility of an engine failure after lift off.
FYI The Ansett F28 also operated BNE-ISA-BNE for a brief period.