After prolonged bad weather he and Lincoln Hall radioed to the Expedition Leader, Peter Cocker, that they wanted to make another attempt on East Dunagiri.
[10][11] Mt Everest historian, Walt Unsworth, described it as "one of the greatest climbs ever done on the mountain"[12] and American climber, John Roskelley, said, "the Aussies pulled off the coup of the century".
The climb up the previously-unclimbed north west ridge proved difficult; it was one "that challenged even Macartney-Snape’s legendary strength and endurance at high altitude.
[14] After a night without sleeping bags or stove at just under 8000m Child, Macartney-Snape and American Tom Hargis had finally made the coveted second ascent of Gasherbrum IV.
While planning the expedition, Macartney-Snape and his then wife, Dr Ann Ward, were living in Meekatharra, Western Australia where she was stationed with the Royal Flying Doctor Service.
Macartney-Snape trained for the upcoming expedition with demanding runs in the 40-degree heat of the surrounding bush and short, solo climbs on the large boulders around Meekatharra.
He was joined by Ward, his sister Pip, film-maker Mike Dillon, Nepali cook Tenzing Sherpa and Charles Norwood, who drove a Land Rover with gear for the trek.
He reached nearly 7500m on acclimatisation sorties, but bad weather and a strong avalanche risk changed Macartney-Snape's plans to ascend via the South Col route.
After two preparatory trips through the Khumbu Icefall to the Western Cwm, he left his team on 7 May to attempt the summit solo and without supplemental oxygen, carrying a pack with a tent, food, fuel and a movie camera to the South Col at 8000m.
Light-headed and plagued by bouts of diarrhoea following the challenging solo climb up the Lhotse Face, Macartney-Snape rested a day before setting out for the summit of Everest at 9.30pm on 10 May in bright moonlight.
Climbing solo, weak with nausea and diarrhea and having eaten little in the previous days, it took nearly six hours in −30 °C (−22 °F) cold for him to ascend from 8,230 m and 8,536 m, nearly falling to his death at midnight when stopping to adjust the movie camera he carried.
On the summit he unfurled the flag of the Australian Geographic Society, his sponsor, and that of the Foundation for Humanity's Adulthood (now named the World Transformation Movement).
[19] In 2010 Macartney-Snape successfully summited a 6,500m unclimbed peak in remote Eastern Nepal with a team that included four members of the ANUMC Himalayan Expedition of 1978 to Dunagiri.
Several months later they met again where Griffith discussed his ideas with Macartney-Snape and gave him a draft copy of his first book Free: The End of the Human Condition.