Chin was born in Portland, Oregon to a Peruvian mother and a Chinese father of Taishanese origin. Motivated by the Japanese invasion of China, Chin enrolled in flight school in 1932, and along with 13 other Chinese Americans including John Buffalo Huang Xinrui and Hazel Ying Lee, he left for China and joined the Canton Provincial Air Force under General Chen Jitang as the first and original group of American volunteer combat aviators, and from there was sent to additional aerial-gunnery training with the Luftwaffe at Lagerlechfeld, Germany; returning to China to see the Guangdong Provincial Air Force integrated into the central government's air force under the KMT. As full-scale war broke out with the Battle of Shanghai, he initially flew in combat with the 28th Pursuit Squadron of the 5th Pursuit Group of Curtiss Hawk IIs, and later the Gloster Gladiator, ultimately credited with destroying nine enemy aircraft between 1937 and 1939. In 1939, while flying a Gloster Gladiator, the fighter in which he scored 6.5 of his 8.5 aerial victories, he was hit by enemy fire and forced to bail out of his burning aircraft, and although he parachuted to safety, he suffered serious burn injuries. Nevertheless, after several years of surgery and recovery, and an escape from the Japanese occupation of Hong Kong, he returned to China in 1944 to fly supplies over the Himalayas, a route known as the Hump.