8.33 kHz implementation support

Coordinating and supporting the implementation of air-ground communications via the very high frequency 8.33 kHz channel spacing, on behalf of the European Commission.

Air-ground communication using very high frequency (VHF) 8.33 kHz channel spacing is being progressively introduced in European airspace to alleviate VHF congestion.

Our role

At EUROCONTROL, in our capacity as Network Manager (NM), we provide support to all stakeholders involved in 8.33 kHz deployment (airspace users, service providers, industry, regulatory organisations, etc.) on behalf of the European Commission (EC). We give recommendations on:

  • institutional provisions,
  • deployment management,
  • flight planning,
  • operational procedures,
  • aircraft retrofit,
  • safety and
  • frequency management aspects.

Through our ‘8.33 implementation support’ project and its associated 8.33 Implementation Support Group, we monitor and steer the implementation of the voice channel spacing regulation. In addition, we provide information to increase awareness about deployment rrequirements and coordinate any exemptions and provide the community with assessments of the potential impact on the network.

We also develop:

  • 8.33 Coordinated Deployment Plans,
  • Risk Analysis and Mitigation reports,
  • 8.33 kHz Deployment guidance documentation,
  • Network impact assessments (in coordination with RFF) for States implementation and exemption plans.

You can find out more by registering for our 8.33kHz implementation support group workspace.


8.33kHz implementation support group workspace


Through the deployment of 8.33 VCS in the entire European airspace, the availability of new communication channels will facilitate:

  • the creation and modification of ATC sectors to better match traffic flows,
  • the creation and modification of services like approach, tower, ATIS and OPC,
  • the possibility of allocating additional special use frequency assignments for general aviation activities (e.g. special events, competitions, air shows) as well as creating new services (new ATIS/AFIS, aerodromes, etc.),
  • the provision of backup services and spare assignments for avoiding interference and
  • the accommodation of new requirements such as the extension of the VHF Data Link (VDL) services in the band 136.700 to 136.975 MHz or newly-developed SESAR concepts (e.g. sector-less ATC).

Support and guidance to military operators

At EUROCONTROL, we support military authorities on the implementation of the air-ground voice channel spacing (AGVCS) provisions applicable to State aircraft and military infrastructure. Such guidance is available in our Guidelines on 8.33 kHz channel spacing for military operators.

To support the EUROCONTROL Network Manager’s 8.33 kHz Implementation Support Group (ISG), we regularly collect the most recent 8.33 equipage plans for State aircraft. The responses show that State aircraft operators are making a significant effort to comply with the 8.33 kHz requirement as regulated in the Commission Implementing Regulation 1079/2012 of 16 November 2012. Equipage levels for transport type State aircraft will reach 88.7% by 2020, there is virtual 100% UHF equipage and a significant number of ageing fleets will go out of service before 2025.

Background information

In 1999, some 30 States in the ICAO EUR region enforced the mandatory carriage of 8.33 kHz radios above Flight Level (FL) 245.

Following this decision, the European Commission (EC) undertook to regulate the implementation of VHF 8.33kHz voice channel spacing in European airspace below FL245 down to FL195 (Air Ground Voice Channel Spacing (AGVCS) Implementing Rule (IR) - EC Regulation No 1265/2007) and then further below FL195. The final regulation (VCS Regulation) was published in the Official Journal (EU No 1079/2012 or L320/14) of 16 November 2012 and amended in July 2013, (EU) No 657/2013.

VCS Regulation milestones

The Voice Channel Spacing (VCS) regulation extends the requirements, covered in Regulation (EC) No 1265/2007, for the coordinated introduction of air-ground based voice communications based on 8.33 kHz channel spacing, to the lower airspace (below FL195).

The Regulation applies to all radios operating in the VHF band, to flight data processing systems serving general air traffic and to all flights operating as General Air Traffic/civil (GAT) in the ICAO EUR region airspace. It contains interoperability, performance and deployment obligations, with relevant application dates, for the manufacturers of radios, ANSPs (air navigation service providers), operators and other users of radios, Member States and NM. It includes operational procedures based on ICAO’s provisions, as well as specific arrangements for State aircraft, and provisions for exemptions.

Very High Frequency (VHF) communications channels in radiotelephony

Communication problems arising from the mistuning of VHF channels represent an important safety and security risk to air traffic management.

The implementation of 8.33 kHz channel spacing in the ICAO EUR Region (October 1999) introduced a requirement to specify 8.33 kHz channels, in VHF radiotelephony communications, using all 6 digits of the channel name, preceded by the term “CHANNEL”. However, procedures associated with the indication of 25 kHz channels, specified in 4 or 5 digits, were unchanged.

When using radio management panels displaying 6 digits, situations arose where flight crews were uncertain as to whether a ‘0’ or a ‘5’ was to be tuned as the sixth digit of the VHF channel. Moreover, the term “CHANNEL” was increasingly omitted when specifying 8.33 kHz channels.

Revised procedure

Revised communication procedures were developed to mitigate the risk of mistuning. The revised communication procedures were finalised by the International Civil Aviation Organization (ICAO) and promulgated in the form of Amendment 80 to the ICAO Annex 10, Volume II (Communication Procedures).

ICAO Annex 10, Volume II

Amendment 80 to ICAO Annex 10, Volume II - Aeronautical Telecommunications - became applicable on 24 November 2005. It introduced a procedure requiring all VHF voice communication channels to be indicated by the use of 6 digits (4 digits for the case of channels ending in two zeros), irrespective of whether 25 or 8.33 kHz channel spacing is used, e.g.:

  • 118,005 specified as "ONE ONE EIGHT DECIMAL ZERO ZERO FIVE"
  • 118,025 specified as "ONE ONE EIGHT DECIMAL ZERO TWO FIVE"
  • 118,100 specified as "ONE ONE EIGHT DECIMAL ONE"