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Request for Support Message  
Safety Subject: Passing of level information when providing Traffic Information
Origin: EUROCONTROL Safety Improvement Sub Group
Date: 11 January 2013
Distribution: Air Navigation Service Providers, Aircraft Operators, Aviation Authorities



Passing of level information when providing Traffic Information


SYNOPSIS

The EUROCONTROL Safety Improvement Sub Group (SISG) is aware that when providing traffic information some air traffic controllers routinely use “relative vertical position” (e.g. “1000ft above/below”) as the ‘level’ reference for other aircraft rather than referring to the other aircraft’s actual or expected level (i.e. its flight level, or altitude/height in metres or feet) as described in ICAO PANS ATM. This practice has been adopted because pilots receiving PANS ATM compliant traffic information sometimes misinterpret the ‘level’ information as an instruction to climb/descend to the stated level rather than assimilate it as traffic information about another aircraft. This problem can be exacerbated on a busy frequency and the use of different languages, accents and dialects often compounds any difficulty.

ICAO REQUIREMENTS & GUIDANCE

ICAO PANS ATM 12.3.1.1 describes how the word ‘level’ should be used in the context of ATC Phraseology, namely:

“Circumstances: DESCRIPTION OF LEVELS (SUBSEQUENTLY REFERRED TO AS “(LEVEL)”)
Phraseologies: a) FLIGHT LEVEL (number); b) (number) METRES; or c) (number) FEET.”


Subsequently at ICAO PANS ATM 12.3.1.6, the word ‘level’ is included in the phraseologies to be used by ATC when providing traffic information.

ANALYSIS

Traffic information is intended to improve pilots’ situational awareness.  In response to unwanted manoeuvres and flight safety concerns, some national authorities and ANSPs permit controllers to use “relative vertical position” as an alternative way to pass level information.  For example, “traffic, 12 O’clock, 6 miles, opposite direction, 1000ft above/below”.  In some circumstances, e.g. when passing traffic information to an aircraft which is climbing or descending, the words “cleared level” are added, i.e. “…1000ft above/below cleared level” to provide additional clarity and situational awareness.   
 
However, the use of “relative vertical position” across Europe is not uniform.  SISG members wish to have more information about, and a better understanding of, the use of this practice with a view to assessing if it would be beneficial to consider changes to the current ICAO PANS ATM ‘level’ phraseology when passing traffic information.

SUPPORT REQUESTED
 
The purpose of this message is to gather information about current operational practices and preferences with a view to informing ongoing debate on the topic.  
 
ANSPs and national aviation authorities are therefore kindly invited to share their experiences related to the issue and provide information concerning:
  • Any policy they have in force that permits controllers to use “relative vertical position” reporting when providing traffic information.
  • Any recorded safety occurrences and statistical data that support the use of the “relative vertical position” technique as an alternative way to pass traffic information.
  • How and when controllers are trained in the use of “relative vertical position” phraseology, e.g. during ab initio training, continuation training etc.
  • How the policy is promulgated and accessible to both controllers and pilots: e.g. as a filed ICAO “difference”, an AIP entry, in national or unit ANSP phraseology procedures or in widely available phraseology guidelines such as UK CAP 413.
Aircraft operators are also kindly invited to share their experiences and preferences on this issue.

FURTHER READING
  • ICAO Doc 3492: Manual of Radio Telephony.
For more information contact, EUROCONTROL Safety Alerts Coordinator, Richard Lawrence

DISCLAIMER

© European Organisation for Safety of Air Navigation (EUROCONTROL) January 2013. This alert is published by EUROCONTROL for information purposes. It may be copied in whole or in part, provided that EUROCONTROL is mentioned as the source and to the extent justified by the non-commercial use (not for sale). The information in this document may not be modified without prior written permission from EUROCONTROL. The use of the document is at the user’s sole risk and responsibility. EUROCONTROL expressly disclaim any and all warranties with respect to any content within the alert, express or implied.

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