The customary minimum altitude prohibited descent below 6000 feet even under good weather conditions, but a combination of factors led the captain to believe the plane was over the sea (the middle of McMurdo Sound and few small low islands), and previous flight 901 pilots had regularly flown low over the area to give passengers a better view, as evidenced by photographs in Air New Zealand's own travel magazine and by first-hand accounts of personnel based on the ground at NZ's Scott Base.