In May 1999, Joao Garcia summited Everest north side without supplementary oxygen. 2 hours later Joao went down and brought Belgian mate Pascal Debrouwer back with him to the top. The triumph turned into a disaster on descent; when Joao separated from Pascal on the second step.
Joao spent the night in the open, and the next day tried to search for Pascal with emergency oxygen he had fetched in C3. Still without O2 (as Pascal had the only mask and regulator) and severely frostbitten Joao didn’t make it far and his friend was lost. Read article at LINK