From halfway through the Khumbu Icefall (Base Camp is well below 17,400'), map shows route of Canadian Expedition. 1. Site of icefall collapse; 2. Site of Avalanche; 3. Approximate start and path of avalanche; 4. Camp I (19,600'); 5. Camp II (20,700'); 6. Camp III (23,000'); 7. West Face of Nuptse; 8. Lhotse Face; 9. Summit of Lhotse; 10. Camp IV (26,100')

THE ROUTE

In recent years small rapid and lightweight expeditions have been perceived as a greater mountaineering challenge than the old-style ‘siege’ attacks, involving tons of equipment and heavy support. The large scale expeditions, however, are still seen as necessary when facing an unusually hard obstacle.

The hurdle the Canadians had expected to face was the South Pillar on Everest, a previously unclimbed and extremely difficult route from the top of the Western Cwm 8,000 feet straight up to the summit.

After the accidents, the team felt it no longer had the climbing strength to succeed on this route: the switch to the South Col route, pioneered by Hillary and Tenzing, required half the manpower and half the supplies. At this point, the large Canadian expedition became a light, small and flexible alpine attack.