• With an increasing trend of Airprox between military and civilian users in the UK Low Flying System (UKLFS),   the CAA is supporting a military led trial of a VHF Low-Level (LL) Common frequency to be used across the UK so members of the GA community can be better integrated with other users of low level airspace and to help build situational awareness for all users. This should, in turn, reduce the risk of Mid-Air Collision. In 2015, a similar trial was carried out in Scotland, which proved to be very successful.

    The trial: ‘VHF LL Common’ will launch from 1 June 2021 to 1 June 2022, as an information service on the VHF Frequency 130.490.  It is available for use by all aircrew, military and civilian, operating in Class G airspace at or below 2000’ Above Ground Level in the UKLFS. (See below for more details on the UKLFS)

    When and How to use the VHF Low Level Common Frequency

    Pilots should make use of the Low Level Common Frequency only when not in receipt of a Lower Airspace Radar Service (LARS) or other Air Traffic Service, or when operating outside an area where a Frequency monitoring code and the associated ATC frequency is used.  Pilots should make Blind Calls on the Low Level Common Frequency as shown below. To prevent clutter on the air the frequency must not be used as a chat frequency and transmissions should be accurate, clear and concise.

    Transmission Timing:

    • When safe and suitable to do so
    • When entering/exiting the Low Flying System
    • At turning points or significant heading changes
    • Approaching well-known and recognisable physical features
    • Any time it is considered beneficial to the safety of the aircraft

    Blind Call Content:

    • Aircraft callsign
    • Aircraft type (and number, in the case of formations)
    • Position in relation to reference points immediately identifiable to other pilots (using cardinal or inter-cardinal directions)
    • Altitude
    • Heading
    • Next significant reference point

    Example transmissions:

    “G-ABCD, Cessna 152, 8 miles North East of Inverness, 1200 feet, heading south towards Aviemore”

    “G-HELO, R22 Helicopter, 5 miles SE Kendal, 1000 feet, heading East, towards Ripon”

    Please Note:

    Whilst civil aircraft will broadcast their Altitude above sea level based on QNH, military aircraft in the UKLFS will be operating on Radar Altimeter heights and broadcasting their height Above Ground Level. Civil operators should consider their actual height above ground when assessing any potential conflict with military traffic.


    Further information on collision avoidance can be found in the CAA Safety Sense Leaflet 13 - Collision Avoidance   and on the UK Airprox Board website.

    Further information on the UK Low Flying System can be found in the CAA Safety Sense Leaflet 18 – Military Low Flying  and in the UK AIP at ENR 1.10 Section 7 and on charts ENR 6.20 and ENR 6.21.

    Please see the RAF leaflet on this trial 

    To help gauge its success, the CAA is asking for feedback on the trial. Please can you submit any feedback on this via: lowlevelfrequencytrial@caa.co.uk