in China in 1998. On July 7, 1977, Fan Yuanye, a PLAAF pilot flew his Shenyang J-6 numbered 3171 from Jinjiang to an air base in Tainan, and was rewarded a rank of lieutenant colonel in the Republic of China Air Force. After his honorable discharge from the Republic of China Air Force, Fan joined an investment firm with his money and obtained American green card, but he stayed primarily in Taiwan to handle his investments. On April 15, 1979, Yan Wenchang, a distinguished PLAAF pilot who earned numerous awards for his excellent performance in support of the Sino-Vietnamese War, was extremely bitter after learning that the promotion for the deputy squadron commissar was given to somebody else instead of him. Yan felt he was the better candidate and should get the promotion and he was under appreciated, and as a result, he decided to defect to Vietnam after learning that the opportunity would be gone because his unit would soon be redeployed to Hunan, and the only thing he left was a note to his wife that read:I'll be gone, good-bye forever!'''. However, Vietnam did not react at all to his attempts for contacts after his Shenyang J-6 entered Vietnam from Guangxi, and as result, Yan was killed after directly crashing into a 1,000 metre high mountains cliff approximately 80 km south of Haiphong. The Chinese Ministry of Foreign Affairs told Vietnam the next day that the incident was a navigational error and asked for the return of the remains of the pilot and the jet, but Vietnam refused, and instead, asked Soviet investigators to inspect the wreckage. KGB aviation experts discovered that the avionics of Yan's J-6 was extremely rudimentary even by Soviet standard, and was indeed lacking any effective navigational avionics. Furthermore, the communication on the J-6 was not encrypted, and it could be intercepted by advanced civilian radios on the market. Since Yan was a regular pilot that patrolled the airspace within the 10 km of the Sino-Vietnamese border (sometimes as frequent as 4 times a day), his defection was not detected until his crash. On August 7, 1983, Sun Tianqin, a former PLANAF pilot who had just transferred to PLAAF several months ago to become a test pilot, flew a J-7II numbered 045 from Dalian to Seoul Air Base in South Korea. Sun was rewarded a rank of colonel in the Republic of China Air