On 14 July 1934, Willo Welzenbach died whilst preparing to attempt the first ascent of Nanga Parbat. The cause of death was pneumonia resulting from his prolonged stay at altitude, above 7,000 metres, during a terrible storm with temperatures of over 30° below zero. Willo was a great innovator in mountaineering techniques and equipment; for example, he was the first to use ice screws and devised the mountaineering difficulty scale known as the Welzenbach scale, now known as the UIAA scale.