The expedition this year, led by Eric Simonson, hopes to find Irvine's body, and with it a camera and long-frozen film that may settle once and for all whether the pair made it to the top. More than a dozen crevasses are crossed, steep sections exceed 50 degrees, and the single line of rope is clogged in places by climbers heading up or down against the flow of traffic. Those not physically up to the task are sometimes struck down by Acute Mountain Sickness, or worse, the fatal buildup of fluid in their lungs or brains. Breathing passages dry out, and climbers sometimes cough hard enough to break ribs. The thought process misfires and judgment becomes impaired.
Bottled oxygen helps, but it is no substitute for sea-level air.
Climbers are also dependent on the jet stream to dictate when they can move and how high they can go. During the winter months, the air roars across the top of Everest, making travel almost suicidal. As May progresses, the jet stream moves north, away from the summit, leaving a safer climbing window of about two weeks. That is when those who still have the strength and courage make their push to the top. Of course, no one is immortal and luck cannot be carried in a backpack.