<aside> 1️⃣ - Phraseology is the way to communicate between the pilot and air traffic controller (ATC unit) for the purpose of ensuring uniformity in RTF (radiotelephony) communication.

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If standard phrases are adhered to when composing a message, any possible ambiguity will be reduced to a minimum.

<aside> 2️⃣ - Phraseology shows the text of a complete message. They are not intended to be exhaustive, and when circumstances differ, pilots and controllers will be expected to use plain language, which should be as clear and concise as possible.

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<aside> 3️⃣ - As a pilot, you must repeat all air traffic controller clearances and instructions that you received. That’s called the read-back procedure.

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Read-back is defined as a procedure whereby the receiving station repeats a received message or an appropriate part thereof back to the transmitting station so as to obtain confirmation of correct reception.

<aside> 4️⃣ - It’s a mandatory procedure except when a pilot is in state of emergency and he has no time to read back or when the pilot’s radio is broken.

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Source of this phraseology is extracted from ICAO documentation 4444 16th edition dated 10/Nov/2016