A 70-year-old climber who became the oldest American to scale Mount Everest three years ago, is heading to the mountain again at the weekend hoping to climb the world’s tallest peak that straddles the Nepal-Tibet border from both sides. Bill Burke, a native of Costa Mesa, California, said he would first try and climb the 8,850 meter (29,035 feet) mountain from its northern side in Tibet. He will then climb from Nepal taking the same route as Sir Edmund Hillary and Tenzing Norgay Sherpa in 1953. “It is going to be very tight climbing both sides in the same season,” Burke told Reuters in Kathmandu. It is rare for climbers to climb from two sides in the same season because they become tired and have less time to wind up before the onset of annual monsoon rains that batter the Himalayas starting in June. Climbers have traversed Mount Everest - going up one side and down the other - in the past. But China, which allows climbers to go to Mount Everest from Tibet, does not permit them to traverse any more. Hundreds of climbers are on the Tibetan and Nepali sides of Mount Everest during the current climbing season which ends this month. Nearly 3,700 people have climbed Everest and at least 231 have lost their lives in attempts.