ICAO Confirmation Phrases – Readbacks, Cross-Checking & Verification Standards

ICAO Confirmation Phrases

Rigorous confirmation and closed-loop communication protocols are the bedrock of aeronautical radiotelephony. Under ICAO Annex 10 (Volume II), Doc 4444 (PANS-ATM), and Doc 9835, pilots and Air Traffic Control Officers (ATCOs) are evaluated on their ability to positively verify safety-critical clearances, execute flawless readbacks, affirm tactical understanding, and detect hearback discrepancies before an operational breakdown occurs.

To achieve ICAO Level 4 (Operational), Level 5 (Extended), or Level 6 (Expert), candidates must maintain structured verification habits and eliminate ambiguous acknowledgments. This guide organizes essential confirmation language into five core operational areas: Standard Affirmation Terminology, Mandatory Readback Confirmation Items, Distinguishing Roger, Wilco & Affirm, Cross-Checking Altimetry & Lateral Routing, and Model Spoken Exam Drills.

ICAO Confirmation Lexicon Overview

differentiate standardized confirmation markers: AFFIRM, NEGATIVE, ROGER, WILCO, CONFIRM, and VERIFY
master mandatory readback rules for levels, headings, speed limits, runway assignments, and altimeter settings
execute closed-loop cross-checks for visual traffic contact, runway vacating, and ILS localizer interception
verify navigational coordinates, transponder squawk codes, and oceanic SELCAL checks
identify and correct subtle hearback errors in simulated air traffic controller transmissions
practice model spoken exchanges for ICAO Speaking Part 3 interactive scenarios and Part 4 discussions

Step 1: Standard ICAO Confirmation & Verification Terms

Standardized phraseology establishes concise, unmistakable confirmation between flight decks and ground stations. Use official ICAO definitions under Doc 4444:

Confirmation Term	ICAO Definition & Purpose	Model Example Transmission
`AFFIRM`	Yes; confirms that a statement or parameter is correct.	"Radar, Lufthansa 204, AFFIRM, passing flight level one fow-er zero."
`NEGATIVE`	No / Permission not granted / That is not correct / Not capable.	"Tower, Speedbird 882, NEGATIVE, unable to vacate at taxiway Bravo due to gross weight."
`CONFIRM`	I request the originator to check that the following information is correct.	"Geneva Approach, Swiss 412, CONFIRM* cleared for visual approach runway two-two?"*
`ACKNOWLEDGE`	Let me know that you have received and understood this message.	"All stations, severe wind shear reported on final, ACKNOWLEDGE."
`CHECK`	Examine a system, configuration, or procedure.	"Scandinavian 901, CHECK* gear down and locked, tower shows no indication."*

Step 2: Mandatory Readback Confirmation Items

To prevent hazardous misunderstandings, ICAO strictly mandates verbatim readbacks of critical control directives. Never replace these items with conversational acknowledgments:

Safety-Critical Item	Required Readback Content	Correct Readback Example
Flight Level / Altitude	Assigned level, climb/descent constraints, and vertical rates.	"Climb flight level three zero zero, cross BOMBI at or above flight level one eight zero, Air France 114."
Heading Instructions	Assigned magnetic headings and turn directions.	"Turn left heading zero fow-er zero, Speedbird 672."
Runway In Use & Clearances	Runway designators, takeoff, landing, conditional lineup, and backtrack clearances.	"Cleared for takeoff runway two seven right, Lufthansa 440."
Altimeter Settings (QNH)	Numerical altimeter pressure settings in hectopascals or inches of mercury.	"QNH one zero one niner, KLM 812."
Transponder (SSR) Codes	Assigned four-digit squawk numbers.	"Squawk fow-er five one two, Austrian 331."

Step 3: Distinguishing Roger vs. Wilco vs. Affirm

Using conversational acknowledgments improperly is a frequent point deduction in ICAO oral assessments. Differentiate operational application:

ROGER: Signifies solely: "I have received all of your last transmission." It confirms receipt of information (e.g., weather updates, traffic advisories), but never confirms agreement or compliance with a control clearance.
WILCO: Signifies: "Your last message has been understood and will be complied with." Used for instructions that do not require a mandatory verbatim readback (e.g., "Report passing flight level one zero zero" → "Wilco, Lufthansa 204").
AFFIRM: Signifies a clear "Yes" to a direct question or verification query. Never substitute colloquial expressions like "yeah", "sure", or "okay".
NEGATIVE: Signifies "No" or inability to comply. Follow with a concise reason when necessary (e.g., "Negative, unable due to high traffic speed").

Standard Communication Rule: The "Roger" Trap

"Never reply with 'Roger' when receiving an altitude, heading, or runway instruction. A clearance is not legally confirmed until all mandatory parameters and your aircraft call sign are read back in full."

Step 4: Operational Verification: Altimetry, Route & Interception

Standard verification exchanges confirm tactical milestones and lateral/vertical positions:

Operational Milestone	Confirmation Phraseology	Operational Purpose
ILS Localizer / Glide Path	"Established on the localizer runway two eight left, Speedbird 404."	Confirms aircraft is locked onto the final approach guidance and tracking inbound.
Runway Vacated	"Runway zero six vacated via taxiway Charlie, Scandinavian 712."	Informs the tower controller that the active runway is clear for subsequent traffic.
Visual Traffic Contact	"Looking out... Traffic in sight, maintaining visual separation, Ryanair 812."	Confirms visual identification and transfers spacing responsibility to the flight crew.
SELCAL Verification	"Shanwick Radio, Lufthansa 400, SELCAL check Alpha-Bravo-Charlie-Delta."	Verifies high-frequency selective calling system operation prior to entering oceanic airspace.

Step 5: Practical Spoken Application & Model Exam Drills

Examine how confirmation phrases and closed-loop readbacks are structured during ICAO oral examinations:

Drill 1: Verifying an Unclear Conditional Lineup Clearance (Part 3 Role-Play)

Examiner (as ATC): "Lufthansa 342, behind the landing Boeing 737, line up and wait runway two-five left behind."
Candidate (as Pilot): "Behind the landing Boeing 737, line up and wait runway two-five left behind, traffic in sight, Lufthansa 342."

Drill 2: Confirming Altimeter Setting Discrepancy (Part 3 Problem Solving)

Examiner (as ATC): "Swiss 188, confirm passing altitude fow-er thousand five hundred feet on QNH one zero zero eight."
Candidate (as Pilot): "Negative, Zurich Control. We are currently passing altitude fow-er thousand five hundred feet on QNH one zero one eight. Confirm correct QNH is one zero one eight?"

Drill 3: The Danger of Confirmation Bias in Hearbacks (Part 4 Discussion)

"Confirmation bias occurs when an air traffic controller or pilot hears what they expected to hear rather than what was actually transmitted. For example, if a controller expects a pilot to read back FL320, they might miss a readback of FL300. Closed-loop communication requires active, conscious listening during every readback to break this psychological trap."