On 9 November 1979, Captain Jim Collins and First Officer Greg Cassin, part of the flight crew rostered on Air New Zealand's 28 November Antarctic flight, attended a route qualification briefing. This covered the instrument flight rules (IFR) route to the McMurdo area, including that the minimum instrument meteorological conditions (IMC) altitude until they reached McMurdo was 16,000 ft.
They were also advised of a visual meteorological conditions (VMC) let down procedure over McMurdo whereby they were permitted to descend to a minimum altitude of 6000 ft, provided they were in VMC conditions. Material presented at the briefing, including printouts of a flight plan used for a previous trip, gave the impression that the IFR route would take them over the flat sea ice of McMurdo Sound.
In the early hours of 28 November a navigational coordinate in the flight plan presented at the briefing was changed. The airline’s navigation section believed it was making a minor adjustment to the flight’s longstanding destination point, but a typing error some 14 months earlier meant it had actually shifted this point some 27 nautical miles to the east. Instead of the IFR route taking Flight TE901 over flat sea ice, as Collins and Cassin had been briefed, it would take them directly over Mt Erebus, a 3794-metre-high active volcano. The flight crew were not alerted to the change. On the morning of 28 November they received the adjusted 'correct' flight plan and entered these coordinates into the onboard computer.
Shortly before 8.30 a.m. (NZDT)* on 28 November 1979, Air New Zealand Flight TE901 left Mangere airport, Auckland, for its 11-hour return flight to Antarctica. It was scheduled to arrive over Antarctica between 12 and 1 p.m. (NZST), and from around this time it had ongoing contact with both 'Mac Centre', the United States Navy's air traffic control centre at McMurdo Station, and the 'Ice Tower' at nearby Williams Field. At 12.45 p.m. (NZST) Cassin advised Mac Centre that the aircraft was at 6000 ft in the course of descending to 2000 ft and that it was VMC. This was the final communication from TE901. Four minutes and 42 seconds later, at 12.49 p.m. (NZST), the aircraft crashed into the lower slopes of Mt Erebus, killing all on board.
*On the day of the Erebus disaster there was a one-hour time difference between New Zealand and McMurdo Station. McMurdo Station was operating under New Zealand Standard Time (NZST) while New Zealand was operating under daylight saving or New Zealand Daylight Time (NZDT). Scott Base and McMurdo Station did not begin observing daylight saving until 1992/93.