Effective communication between pilots and air traffic controllers (ATCs) is one of the most critical components of aviation safety. Even minor misunderstandings in air–ground communication can lead to significant safety risks, including airspace infringements, loss of separation, or runway incursions. Recognising the importance of this issue, the International Air Transport Association (IATA), in collaboration with the International Federation of Air Line Pilots’ Associations (IFALPA) and the International Federation of Air Traffic Controllers Associations (IFATCA), jointly conducted a comprehensive study on phraseology usage in global aviation communication.

The resulting publication, Pilots and Air Traffic Controllers Phraseology Study, provides a detailed analysis of communication issues arising from the non-use or misuse of standard phraseology prescribed by the International Civil Aviation Organization (ICAO).

Table of Contents

Pilots and Air Traffic Controllers Phraseology Study

Purpose and Scope of the Study

The primary objective of the study was to investigate the extent to which deviations from ICAO standard phraseology contribute to miscommunication between pilots and controllers. Importantly, the study deliberately excluded the subject of “Aviation English” proficiency — as that topic is already addressed through separate international initiatives — and instead focused exclusively on phraseology usage during operational communication.

Separate online surveys were developed and distributed to pilots and ATCs worldwide. These surveys aimed to:

Identify common scenarios where established phraseology is not used.
Document cases where local or non-standard phrases led to confusion or misunderstanding.
Gather suggestions from operational personnel for improving communication safety.

The results were intended to support the development of actionable safety recommendations and best practice guidelines applicable to all phases of flight — from pushback and taxi to en-route operations and approach/landing.

Executive Summary

The Phraseology Study was initiated by the IATA Operations Committee (OPC) and supported by the IATA Safety Group (SG). Its purpose was to compile first-hand operational insights from pilots and controllers regarding situations where:

The non-use of ICAO-standard phraseology has caused or could cause communication errors.
Locally developed or informal phrases introduce ambiguity or potential safety hazards.

The survey forms an initial risk assessment of air–ground communication practices. By analysing where and how miscommunications occur, the study establishes a knowledge base to guide further research, policy formulation, and training programmes.

Methodology and Survey Framework

The study comprised two tailored surveys:

Pilot Survey: Distributed globally across commercial and cargo flight crews.
ATC Survey: Distributed to operational controllers across various air navigation service providers.

Both surveys sought to identify:

Types of Events: Examples of miscommunication or phraseology misuse.
Context of Occurrence: Specific flight phases or operational environments where these issues arise.
Recommendations: Proposed solutions and mitigation measures from frontline professionals.

Key Findings

Survey Participation

Pilots: 1,978 responses
Air Traffic Controllers: 560 responses

A significant observation was the lower participation rate from regions where English is not the primary language of aviation communication. To address this gap, IATA and its partners are translating the surveys into multiple local languages to broaden participation and capture a more representative global perspective.

Identified Communication Challenges

The survey responses highlighted several recurring categories of communication issues:

Non-Standard Phraseology:
- Use of informal language or colloquialisms instead of prescribed ICAO terms.
- Ambiguous phrase structures leading to uncertainty in intent.
Lack of Harmonisation:
- Inconsistent phraseology usage between adjacent airspaces or different ATC units.
- Variation in interpretation of standard phrases across jurisdictions.
Use of Local Language:
- Switching to local languages mid-transmission, leading to exclusion of non-native speakers from critical situational awareness.
- Partial translations or mixed-language messages causing operational confusion.
Incomplete Readbacks and Hearbacks:
- Misunderstood or incorrectly repeated clearances not challenged by ATC or crew.
- Over-reliance on expectation bias in interpreting partial transmissions.
Phraseology Drift in Routine Operations:
- Progressive erosion of phraseology standards over time in non-critical communications.

Safety Implications

Miscommunication between pilots and controllers remains one of the top causal or contributory factors in many aviation safety incidents and accidents. Even when such events do not result in immediate danger, they often lead to increased controller workload, loss of situational awareness, or a need for last-minute corrective actions — all of which elevate operational risk.

Standard phraseology exists precisely to reduce ambiguity and ensure that instructions, clearances, and acknowledgements are concise, predictable, and universally understood. Deviations from this standard undermine that safety buffer.

Recommendations and Next Steps

Based on the survey findings, several key recommendations have been proposed:

Enhanced Training: Regular, scenario-based training for both pilots and controllers focusing on correct phraseology usage.
Reinforcement of ICAO Standards: Stronger regulatory emphasis on adherence to standard phraseology in all operational manuals and procedures.
Cross-Regional Harmonisation: Collaborative initiatives between air navigation service providers (ANSPs) to harmonise phraseology practices, especially across FIR boundaries.
Improved Monitoring and Feedback: Incorporation of communication analysis into safety audits and flight data monitoring programmes.
Translation and Outreach: Expanding the study’s linguistic reach to ensure more representative global data.

Supporting Resources

To complement this study, several toolkits and guides are available to help aviation professionals improve their communication practices:

ALL CLEAR? Toolkit: Practical resources for standardising communication.
SAY AGAIN Phraseology Guide: A quick-reference manual on correct phraseology usage.
Communication Guide for General Aviation VFR Flights: Guidance aimed at non-commercial operations.

Additional reading materials include:

Standard Phraseology
Non-Standard Phraseology
Radio Discipline
Pilot–Controller Communications (OGHFA BN)

The Pilots and Air Traffic Controllers Phraseology Study is a pivotal initiative in enhancing aviation safety by addressing one of its most fundamental components — effective communication. The findings underscore the ongoing need for vigilance, standardisation, and continuous training to minimise misunderstandings in air–ground exchanges.

By strengthening phraseology discipline and promoting a shared global communication culture, the aviation community can significantly reduce the risk of operational incidents and continue to uphold the exceptionally high safety standards that define international air transport.