ICAO Clarification Phrases

The ability to seek immediate, unambiguous clarification is one of the most critical safety skills evaluated under the ICAO Language Proficiency Assessment (Doc 9835, Annex 10, and Doc 4444). During oral flight tests and simulator evaluations, examiners evaluate whether pilots and Air Traffic Control Officers (ATCOs) can actively identify communication breakdowns, query ambiguous clearances, request targeted repetitions, and resolve conflicting information before an operational error occurs.

To achieve ICAO Level 4 (Operational) through Level 6 (Expert), candidates must never guess the meaning of an incomplete transmission. Instead, they must deploy standard radiotelephony clarification terms and agile plain English repair strategies. This guide organizes essential clarification language into five operational categories: Standard ICAO Clarification Terminology, Resolving Clipped & Distorted Transmissions, Clarifying Numbers, Levels & Phonetics, Managing Fast Speech & Accents, and Practical Exam Drills.

Step 1: Standard ICAO Radiotelephony Clarification Terms

Standardized phrases form the first line of defense against misunderstanding. Use exact ICAO terminology according to Doc 4444:

Standard Phrase	Official ICAO Meaning	Operational Example Transmission
SAY AGAIN	Repeat all, or the specified part, of this message.	"Shannon Control, Lufthansa 458, SAY AGAIN assigned flight level."
WORDS TWICE	As a request: Communication is difficult, please send every word/group twice. As info: Since communication is difficult, every word will be sent twice.	"Radio signal unreadable due to severe static, request WORDS TWICE."
SPEAK SLOWER	Reduce your rate of speech.	"Tower, Scandinavian 901, SPEAK SLOWER, non-native speaker on frequency."
CORRECTION	An error has been made in this transmission (or message indicated). The correct version is...	"Turn right heading two seven zero, CORRECTION, heading two niner zero."
VERIFY	Check and confirm with originator.	"Swiss 312, VERIFY passing flight level one fow-er zero."
CONFIRM	I request the originator to check that the following information is correct.	"Bordeaux Radar, Speedbird 114, CONFIRM cleared direct waypoint KILDU?"

• ICAO ATC Vocabulary
• Aviation Phraseology vs. Plain English
• Clear Radio Communication

Step 2: Resolving Clipped, Partial & Distorted Transmissions

Requesting a complete transmission repetition during high traffic density wastes valuable airtime. Master targeted partial clarification queries:

Transmission Problem	Targeted Clarification Phrase	Aviation Context
Beginning of message blocked	"Say again all before [known waypoint / instruction]."	"Radar, Speedbird 224, say again all before 'descend to three thousand feet'."
End of message clipped	"Say again all after [known waypoint / instruction]."	"Control, Air France 810, say again all after 'cleared direct to DIK'."
Middle section garbled by static	"Say again between [word A] and [word B]."	"Tower, KLM 641, say again between 'line up and wait' and 'runway zero six'."
Simultaneous transmission (Step-on)	"Simultaneous transmission, station calling with emergency, say again call sign only."	Used when dual carrier waves produce high-pitched squeal on frequency.

• Non-Standard Communication
• Radio Communication Listening
• Fast Speech Listening Practice

Step 3: Clarifying Numbers, Levels, Headings & Phonetics

Numerical digits are the most frequent source of operational altitude deviations and runway incursions. Apply standardized verification rules:

• Pronouncing Individual Digits: Ensure clarification requests pronounce digits individually (e.g., "Confirm level is one-zero-thousand or flight level one-zero-zero?").
• Phonetic Alphabet Usage: Spell critical waypoint names and intersection fixes phonetically to eliminate regional pronunciation misunderstandings (e.g., "Confirm waypoint name: Delta - Echo - Mike - Oscar - Sierra").
• Distinguishing Similar Sounding Numbers: Clarify potential confusion between "fifteen" and "fifty" or "thirteen" and "thirty" by requesting explicit digit-by-digit readouts (e.g., "Confirm speed restriction is one-five-zero knots or five-zero knots?").
• Altimeter Setting Clarification (QNH vs. QFE): Always clarify pressure datum if anomalous readings appear (e.g., "Confirm QNH is one zero one eight hectopascals or inches of mercury two niner niner two?").

• ICAO Numbers Pronunciation
• ICAO Alphabet Pronunciation
• Stress and Rhythm in Aviation

Step 4: Managing Fast Speech, Heavy Accents & Contradictions

When interacting with non-native speakers or rapid native speakers, deploy structured plain English clarification techniques:

Communication Barrier	Specific Challenge	High-Scoring Clarification Strategy
Rapid Native Speech	Controller uses idioms or speaks at excessive speed during approach sequencing.	"Tower, speak slower please, confirm we are number two for landing behind the Boeing 777?"
Heavy Regional Accent	Vowel shifting or unfamiliar stress patterns obscure waypoint names.	"Radar, your transmission is unclear. Please spell the assigned holding fix phonetically."
Contradictory Instructions	ATC clearance conflicts with FMC profile or published chart constraints.	"Please clarify: published departure procedure requires at or above FL120 at KENO, but we are cleared to FL100. Confirm level."
Unfamiliar Technical Term	Ground handler or controller uses non-standard colloquial terminology.	"Please rephrase your last message in plain English. What specific equipment is required at the stand?"

• Accent Listening Practice
• Confirmation Phrases
• Negotiation Phrases

Step 5: Practical Spoken Application & Model Exam Drills

Examine how clarification phrases are integrated into high-scoring spoken responses during ICAO examinations:

• Problem Solving Role-Plays
• ICAO Speaking Part 4 Discussion
• ICAO Speaking Practice