The initial investigation concluded the accident was caused primarily by pilot error, but public outcry led to the establishment of a Royal Commission of Inquiry into the crash.

The commission, presided over by Justice Peter Mahon, concluded that the accident was primarily caused by a correction made to the coordinates of the flight path the night before the disaster, coupled with a failure to inform the flight crew of the change, with the result that the aircraft, instead of being directed by computer down McMurdo Sound (as the crew had been led to believe), was instead rerouted to a path toward Mount Erebus.

Justice Mahon's report accused Air New Zealand of presenting "an orchestrated litany of lies", and this led to changes in senior management at the airline.

Flight 901 was designed and marketed as a unique sightseeing experience, carrying an experienced Antarctic guide, who pointed out scenic features and landmarks using the aircraft's public-address system, while passengers enjoyed a low-flying sweep of McMurdo Sound.

The aircraft would make a 45-minute stop at Christchurch for refuelling and a crew change, before flying the remaining 464 miles (747 km) to Auckland, arriving at 9:00 pm.

The 182nd DC-10 to be built, and the fourth DC-10 to be introduced by Air New Zealand, ZK-NZP was handed over to the airline on 12 December 1974 at McDonnell Douglas's Long Beach plant.

Due to a typing error in the coordinates when the route was computerised, however, the printout from Air New Zealand's ground computer system that was presented at the 9 November briefing corresponded to a southerly flight path down the middle of the wide McMurdo Sound, about 27 nautical miles (50 km; 31 mi) to the west of Mount Erebus.

[14] The flight had earlier paused during the approach to McMurdo Sound to carry out a descent, via a figure-eight manoeuvre, through a gap in the low cloud base (later estimated to be at around 2,000 to 3,000 feet (610 to 910 m)) while over water to establish visual contact with surface landmarks and give the passengers a better view.

Outside, a layer of clouds blended with the white snow-covered volcano, forming a sector whiteout – no contrast between ground and sky was visible to the pilots.

As it was little understood, even by experienced polar pilots, Air New Zealand had provided no training for the flight crew on the sector whiteout phenomenon.

The CVR recorded the following:[nb 2] The pilots had begun a terrain escape manoeuvre by applying full (go-around) power, but it was too late.

[10] McMurdo Station attempted to contact the flight after the crash, and informed Air New Zealand headquarters in Auckland that communication with the aircraft had been lost.

Airport staff initially told the waiting families that the flight being slightly late was not unusual, but as time went on, it became clear that something was wrong.

[26] The fact that we all spent about a week camped in polar tents amid the wreckage and dead bodies, maintaining a 24-hour work schedule says it all.

Because of this, we had to pick up all the bodies/parts that had been bagged and create 11 large piles of human remains around the crash site in order to bury them under snow to keep the birds off.

Extensive photographic footage, including video, from the moments before the crash was available; being a sightseeing flight, most passengers were carrying cameras, from which the majority of the film could be developed.

[10]: 3.73  The customary minimum altitude prohibited descent below 6,000 feet (1,800 m) 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.

In response to public demand, the New Zealand government announced a further one-man Royal Commission of Inquiry into the accident, to be performed by Justice Peter Mahon.

This Royal Commission was initially handicapped in that the deadline was extremely short; originally set for 31 October 1980, it was subsequently extended four times.

Mahon concluded that the single, dominant and effective cause of the crash was Air New Zealand's alteration of the flight plan waypoint coordinates in the ground navigation computer without advising the crew.

Due to whiteout conditions, "a malevolent trick of the polar light", the crew were unable to visually identify the mountain in front of them.

Furthermore, they may have experienced a rare meteorological phenomenon called sector whiteout, which creates the visual illusion of a flat horizon far in the distance.

[32][37] Aviation researcher John King wrote in his book New Zealand Tragedies, Aviation: They demolished his case (Mahon's case for a cover-up) item by item, including Exhibit 164, which they said could not "be understood by any experienced pilot to be intended for the purposes of navigation" and went even further, saying there was no clear proof on which to base a finding that a plan of deception, led by the company's chief executive, had ever existed.

[43] The Air New Zealand DC-10 fleet was grounded until the FAA measures were rescinded five weeks later, on 13 July, after all carriers had completed modifications that responded to issues discovered from the American Airlines Flight 191 incident.

Almost all of the aircraft's wreckage still lies where it came to rest on the slopes of Mount Erebus, as both its remote location and its weather conditions can hamper any further recovery operations.

"[49] In 2009, Air New Zealand's CEO Rob Fyfe apologised to all those affected who did not receive appropriate support and compassion from the company following the incident, and unveiled a commemorative sculpture at its headquarters.

[50][51] On 28 November 2019, the 40th anniversary of the disaster, New Zealand Prime Minister Jacinda Ardern, along with the national government, issued a formal apology to the families of the victims.

[71] However, the 2023 Auckland Anniversary Weekend floods and Cyclone Gabrielle led to "significant land slips occurring along the cliff line," including one in the vicinity of the memorial site.

[75][76][77] In 2014, a feature-length docudrama, Operation Overdue, on the disaster was produced for TVNZ, focusing on the namesake recovery mission and 11 police officers who helped recover victims' bodies.

[79] Material related to the Erebus disaster and inquiry is held (with other Antarctica items from the Antarctic Division of the (former) Department of Scientific and Industrial Research (DSIR)) by Archives New Zealand, Christchurch.