单选题 Prior to starting transmission, a pilot or controller should .

单选题 CCA385, 8 miles from touchdown, Tower 118.1.

单选题 According to ICAO, a distress message on 121.5 Mhz should begin with .

单选题 In RTF communication, the A/C call sign 9099Y is spoken as .

单选题 The radio call to alert ground personnel when an A/C is having difficulty, but is in no immediate danger, is

单选题 In which case a controller is not supposed to say NEGATIVE.

单选题 _______ means the average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night.

单选题 The SSR code for an A/Cin distress is .