Taking CA1585 as an example, CA is the code of Air China, the first digit 1 indicates North China, where Air China is based in Beijing; the second digit 5 indicates East China, where Yantai is located; the last two digits 85 is the flight number, and the last digit 5 is an odd number, which means that the flight is an outbound flight, and the return flight from Yantai to Beijing is CA1586.
Another example is MU5533, the Shanghai ------ Yantai flight, MU is the code of China Eastern Airlines, the first digit 5 means East China, the base of China Eastern Airlines is in Shanghai; 5 means East China, Yantai belongs to the East China region; 33 is the flight serial number, singular is the flight to go. MU5534 is the return flight from Yantai to Shanghai by China Eastern Airlines.
International flight numbers are organized by the airline code plus three digits. The first digit indicates the airline, and the last two are the flight number, which is the same as the domestic flight number, with the single digit for the outbound trip and the double digit for the return trip. For example, MU508, from Tokyo to Beijing, is a return flight operated by China Eastern Airlines.
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