相关题目
If air-ground communication failure occurs, the pilot should （ ）.
To transfer communication with an A/C to another unit, the controller should pass instructions giving （ ）.
Readback is necessary in RTF because （ ）.
A controller should pass ATC clearance to a pilot at the time （ ）.
In which case a controller is not supposed to say NEGATIVE（ ）.
After receiving takeoff clearance, pilot must takeoff within （ ） minutes or he will ask for a new clearance/.
The abbreviated call sign of N357826 is （ ）.
In RTF communication, the A/C call sign 9099Y is spoken as （ ）.
Prior to starting transmission, a pilot or controller should （ ）.
When flying in the mountainous area, and there is strong wind or strong updraught/downdraught, the aircraft should maintain at least （ ） meters minimum safety altitude from the obstacles.
