Aviation English and Phraseology
Domain 10 tests the language standard behind safe radiotelephony: ICAO Language Proficiency Rating Scale Level 4 and the disciplined use of standard phraseology, with plain language only when standard phrases do not cover the situation.
The six criteria
ICAO assesses pronunciation, structure, vocabulary, fluency, comprehension and interactions. Level 4 is operational. A controller must be understood by the international community and must understand pilots whose accents differ from their own.
Phraseology discipline
Use standard phrases first: hold short, line up and wait, cleared for take-off, go around, say again, correction. Readback is part of the loop, not a courtesy. Plain language is for unexpected situations; it must still be clear, brief and unambiguous.
Worked example: ground control says, Iran Air 456, hold short of runway 29L. The pilot reads back, holding short runway 29L. That readback is correct and does not authorise entering the runway. If the controller intended the aircraft to enter and wait, the correct instruction is line up and wait runway 29L. The difference is operational, not stylistic.
Traps: treating a strong accent as low proficiency; using roger as a readback; accepting a readback that omits the runway or level; replacing standard phrases with conversational English under pressure.