She did not really understand the purpose or the content of these transmissions, but after a few minutes she was able to pick out certain patterns. Many of the transmissions began with a Chinese-accented voice saying "Xiamen Center" followed by the name of an aircraft manufacturer such as "Boeing" or "Airbus" or "Gulfstream" followed by a series of letters and numbers. Then a series of laconic instructions concerning altitude or heading or radio frequency. She reckoned that these transmissions all originated from an air traffic control center responsible for Xiamen’s airspace and that they were bossing the pilots of various airplanes around. In almost all cases, another voice would respond directly, frequently speaking in an English or American or European accent, repeating the series of letters and numbers that seemed to be their plane’s call sign, and then acknowledging the command with "Roger" followed by repeating the instructions out loud, presumably just to be sure that they’d gotten the details correctly. Occasionally, though, a transmission would go unacknowledged, and then Xiamen Center would have to repeat it; and if that failed, they might ask some other plane to relay the message. All of which was done with absolute, deadpan calm, which made sense given that it was what these people did all day, every day, just like bagging groceries or driving a truck. Twice she recognized the voice of Pavel acknowledging one of these transmissions, and in that way she learned the call sign of the plane on which she was a passenger, or rather a prisoner.