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单选题
When an aircraft station fails to establish contact with the aeronautical station on the designated frequency, it shall （ ） ．
A
attempt to establish contact on another frequency appropriate to the route
B
attempt to establish communication with other aircraft or other aeronautical stations on frequencies appropriate to the route
C
transmit its message twice on the designated frequencies, preceded by the phrase “Transmitting blind”
D
any one of the above procedures that is practicable
答案解析
正确答案：D
