This is defined as Detroit Metropolitan Wayne County Airport (DTW) and Shanghai Hongqiao Intl Airport (SHA). Codes like Shanghai Hongqiao Intl Airport are often used to just call airports uniquely. Shanghai Pu Dong Airport (PVG), Guangzhou Baiyun Airport (CAN), Beijing Capital Airport (PEK), Shenzhen Airport (SZX), Qingdao Jiaodong Intl Airport (TAO) are other airports near this flight route and their unique identifiers/IATA codes.