Communications, Phraseology and Radiotelephony
Standard phraseology
Use ICAO standard phraseology: read-back of clearances, standard words (ROGER, WILCO, AFFIRM, STANDBY, CLEARED, LINE UP AND WAIT), and the phonetic alphabet. Numbers are transmitted digit by digit for levels, headings and frequencies. Traps: using non-standard words, failing to read back safety-related items (runway, level, heading, frequency, altimeter setting), and confusing "line up and wait" with "cleared for take-off".
Read-back requirements
Safety-related clearances must be read back: runway clearance, level instructions, heading/speed instructions, altimeter settings, and frequency changes. A controller must verify the read-back.
Communications failure
Know the standard lost-communication procedures: squawk 7600, maintain last assigned level for a specified period, then follow the flight plan; the controller separates the aircraft and protects its route. Traps: confusing 7600 (radio failure), 7500 (unlawful interference) and 7700 (emergency).
Rule of thumb
If it affects safety, read it back. If it is a clearance, it must be acknowledged verbatim.
Worked example
Controller: "ABC123, cleared to land runway 27, wind 270 at 10." Pilot must read back "cleared to land runway 27, ABC123."