Standard phraseology and ATC communication procedures
This section covers standard phraseology and ATC communication procedures: the ICAO words and readback discipline that make clearances unambiguous.
Core rules
- Use standard words exactly: AFFIRM (yes), NEGATIVE (no), ROGER (received all), WILCO (will comply), STANDBY (wait), SAY AGAIN, I SAY AGAIN, CORRECTION, DISREGARD.
- Read back clearances and instructions that affect safety: runway, altitude or level, heading, speed, frequency, transponder code, and hold-short instructions. The controller must hear the readback; if it is wrong, the controller corrects it.
- Start with the station called, then your callsign. On initial contact use the full callsign; use an abbreviated form only when it is unambiguous or ATC has established it.
- “Roger” is not a clearance and does not mean you will comply; “Wilco” includes “Roger”.
- Request “departure” not “take-off” when asking for a take-off clearance; “take-off” is used by ATC only when issuing the clearance.
Worked example
“Lagos Tower, 5N-ABC, Cessna 172, at holding point Alpha, request departure to the west.” Tower: “5N-ABC, line up and wait runway 18L.” Pilot: “Line up and wait runway 18L, 5N-ABC.” The readback repeats the runway and the instruction; it avoids “take-off” because no take-off clearance has been issued.
Traps
Acknowledging a clearance with “Roger” only; reading back part of a hold-short instruction; using “cleared” when only “line up and wait” was given; and assuming a callsign abbreviation is always allowed.