For 80-year-old ultramarathon runner Bob Becker from the United States, tackling the rugged terrain of the Gaoligong Mountains in Tengchong, Yunnan province, last month carried a deep personal meaning.

"I thought if I looked into the sky over 80 years earlier, my father would be up there. We were in the same space—very close—despite being far apart in years," said Becker.

His father, Marston "Mickey" Becker, a bombardier and gunner, was stationed in India and flew through the Himalayas to support Chinese and US war efforts during World War II. Becker's uncle, Sidney Plotkin, stationed in India and China, was involved in several air combat operations in Yunnan.

During the Chinese People's War of Resistance Against Japanese Aggression (1931-45), US airmen flew over the peaks on the perilous "Hump" route from India to Kunming, Yunnan, to deliver supplies in support of Chinese and US troops on the ground fighting Japanese invaders.

The US airmen were part of the Flying Tigers, officially known as the American Volunteer Group.

They were writing a legendary chapter of solidarity between China and the US through sheer courage, Becker said.