not correspond with the approved route. Captain Leslie Simpson, the pilot of a flight on 14 November and also present at the 9 November briefing, compared the coordinates of the McMurdo TACAN navigation beacon (about east of McMurdo NDB), and the McMurdo waypoint that his flight crew had entered into the inertial navigation system (INS), and was surprised to find a large distance between the two. After his flight, Captain Simpson advised Air New Zealand's navigation section of the difference in positions. For reasons that were disputed, this triggered Air New Zealand's navigation section to update the McMurdo waypoint coordinates stored in the ground computer to correspond with the coordinates of the McMurdo TACAN beacon, despite this also not corresponding with the approved route. The navigation section changed the McMurdo waypoint co-ordinate stored in the ground computer system around on the morning of the flight. Crucially, the flight crew of Flight 901 was not notified of the change. The flight plan printout given to the crew on the morning of the flight, which was subsequently entered by them into the aircraft's INS, differed from the flight plan presented at the 9 November briefing and from Captain Collins' map mark-ups, which he had prepared the night before the fatal flight. The key difference was that the flight plan presented at the briefing corresponded to a track down McMurdo Sound, giving Mount Erebus a wide berth to the east, whereas the flight plan printed on the morning of the flight corresponded to a track that coincided with Mount Erebus, which would result in a collision with Mount Erebus if this leg were flown at an altitude less than , 12,448-foot (3,794 m) being the top peak of Mount Erebus. The computer program was altered such that the standard telex forwarded to US air traffic controllers (ATCs) at the United States Antarctic science facility at McMurdo Station displayed the word "McMurdo", rather than the coordinates of latitude and longitude, for the final waypoint. During the subsequent inquiry, Justice Mahon concluded that this was a deliberate attempt to conceal from the United States authorities that the flight plan had been changed, and probably because it was known that US Air Traffic Control would lodge an objection to the new flight path. The flight had earlier paused during the approach to McMurdo Sound to carry out a descent, via a figure-eight manoeuvre, through a gap