相关题目
A typical transponder has four windows which can be set to any number between （ ） . This gives a total of 4,096 possible codes.
The “blips” of light on the radar screen are called raw radar （ ） ．
The coded signal transmitted by the （ ） mounted on the radar antenna, causes the aircraft transponder to reply automatically with a specific coded signal.
（ ） is the airborne portion of the secondary surveillance radar system.
Which secondary radar code below is right?
The control unit established to provide Air Traffic Control Service to controlled flights arriving at, or departing from, one or more aerodromes, is （ ）.
When an aircraft station fails to establish contact with the aeronautical station on the designated frequency, it shall （ ） ．
The controller may direct the pilot of the aircraft in distress to “squawk Mayday”. If this is the case, the pilot should （ ） ．
Urgency messages have （ ） over all transmissions except distress messages.
The category symbol for flight forecast is （ ）.
