Forty years ago, flight TE901 left Auckland for an 11-hour sightseeing trip to Antarctica with 257 people on board. It never returned. On that day, 28 November 1979 all those on board died when the DC-11-30 crashed into the side of Mount Erebus on Ross Island.

But how?

Air New Zealand had been operating scenic flights over Antarctica for two years; they had been a great success. On that particular flight, Captain Jim Collins had descended to give passengers photo opportunities of the active volcano. He’d assumed he was on the same course as previous flights, descending over McMurdo Sound.

In the preparation for the flight a mistake was made resulting in coordinates being entered into the aircraft’s INS navigation system differing for the approved route flown previously; what had before been a safe descent to the east now led directly over Mt. Erebus. The crew were not told of the change. In addition, they breached the minimum safety altitude (MSA) of 16 000′ on approach to the area and 6 000′ south of the mountain. The aircraft descended to 2000′ in contravention of the MSA. ‘Sector white out’ conditions led the crew into believing that the mountainside they saw approaching was the Ross Ice Shelf rather than the slopes of the volcano.

At 12:49 pm the cockpit voice recorder captured the warnings from the ground proximity warning system as the aircraft passed through 500 feet. Although go-around power was applied, it was too late. Six seconds later, the aircraft hit the ground at an elevation of 1 467′.

The initial enquiry into the disaster concluded that the pilots were to blame for the accident, primarily for descending below the MSA. Public outrage prompted a further enquiry-the Mahon Inquiry- in 1981 which cleared the crew, laying blame on the airline for altering the fight plan and-crucially-not advising the crew of TE901. Mahon found that the descent was explained by an approval to descend below 6 000′ if authorised by air traffic control at the US McMurdo Sound base. Mahon’s report also accused management of Air New Zealand of a conspiracy to cover-up, but this was later rejected. The disaster and the bitterness surrounding the subsequent inquiries and legal disputes had an enormous effect on the confidence and innocence of New Zealand.

In 2009 the airline apologised for its behaviour in the aftermath of the disaster, but not for the accident itself. However at this year’s anniversary the chairwoman Therese Walsh offered a full apology as did Prime Minster Ardern on behalf of the Government.

The remains of the aircraft still lie on the slopes of Mt Erebus.