Zermatt Switzerland - Sam Branson, the 29-year-old son of British business tycoon Richard Branson, was airlifted from the summit of the Matterhorn on Wednesday after being struck by altitude sickness during a charity challenge.
 
Branson was part of a team attempting the Virgin Strive Challenge, a month-long adventure raising money for Big Change, a charity for young people founded by Sam Branson, his sister Holly, and four of their friends, including Princess Beatrice, the British Queen's granddaughter.
 
The ten-strong team were nearing the end of the 1,000-kilometre challenge which involved journeying from London to the summit of the Matterhorn entirely on their own steam, by running, rowing, cycling, and hiking.
 
Led by mountaineer Kenton Cool, the team were in the final stages of ascending the 4,478 metre Matterhorn, near Zermatt in the canton of Valais, when Branson started to struggle for breath.
 
Speaking in a video published by the team Cool said:  "In the last 250 metres Sam started to show symptoms of altitude sickness. By the time we got to the summit he was emotionally quite fragile, he had acute mountain sickness, he was dry-heaving, vomiting, and I honestly thought he was going to potentially pass out on me."
 
Branson's father, Virgin boss Sir Richard Branson, himself an avid adventurer, was watching the team ascend the mountain from a helicopter and saw his son rescued by a second helicopter.
 
The 64-year-old entrepreneur, quoted by British paper The Mirror, said:  "Sam was finally taken off the mountain, hanging outside of the helicopter, which was as terrifying as the altitude sickness. I watched all of the drama unfold and felt totally helpless."
 
The two of them cried with relief when reunited, he said.
 
Over the past decade an average of six climbers a year have died on the famous peak.
 
Caroline Bishop.