Communications: RT phraseology, distress and clearances
Phraseology and structure
Standard RT uses the standard words: AFFIRM, NEGATIVE, ROGER, WILCO, STANDBY, CLEARED, HOLD, CHECK, RECLEARED, LINE UP AND WAIT, TAKE-OFF. Position reports give identification, position, time, altitude, and the next position with ETA. Read-back is mandatory for safety-related items: clearances, runway assignments, altitude instructions, altimeter settings, headings, speeds and frequencies.
Distress and urgency
MAYDAY ×3 for distress, PAN PAN ×3 for urgency. Distress format: MAYDAY, callsign, nature of distress, position, altitude, heading, speed, intention, pilot qualifications, persons on board. Urgency uses the same pattern prefixed PAN PAN. Silence is imposed by the station in distress or by ATC; a distress call has absolute priority.
IFR and VFR
VFR includes position reports and airspace entry calls; IFR involves reading back route clearances, SID/STAR and holding instructions. A holding clearance contains the fix, inbound track, level and leg length - read them all back.
Transponder codes
7500 unlawful interference, 7600 radio failure, 7700 emergency. Set the emergency code before changing frequency; go to 121.5 MHz or the designated emergency channel. On radio failure, squawk 7600 and follow the lost-communication procedure.
Worked example
ATC: "XYZ123, cleared to take off runway 23, maintain 5 000 ft, heading 240 after departure." Read back: "Cleared take-off runway 23, maintain 5 000 ft, heading 240 after departure, XYZ123." Read back the clearance only, not the whole transmission verbatim, and finish with your callsign.
Traps
Using "standby" as an acknowledgement; omitting the callsign; using non-standard words such as "seen" or "got you"; confusing urgency with distress; failing to read back the altimeter setting.