The aircraft had departed from Taipei at 16:22 local time. The accident occurred 10 hours into the flight. The Boeing 747SP-09 was northwest of San Francisco, cruising at an altitude of . The cockpit crew consisted of Captain Min-Yuan Ho, age 55, First Officer Ju-Yue Chang, age 53, Flight Engineer Kuo-Pin Wei, age 55, Relief Captain Chien-Yuan Liao, age 53, and Relief Flight Engineer Shih-Lung Su, age 41. Captain Ho had approximately 15,500 flight hours, including 3,748 hours on the Boeing 747. The First Officer had more than 7,700 hours with 4,553 of them on the Boeing 747, and the Flight Engineer had approximately 15,500 hours of flight time, including 4,363 hours on the Boeing 747. The accident occurred while the main crew was on duty.