Trial System Information
Alba FSU trials - Description of new HMS functions and procedures

  1. The modified HMS comprises the following main functions:

    1. Measurement/monitoring of helideck ROLL, PITCH, INCLINATION and HEAVE RATE (as previously).
    2. Measurement/monitoring of the new helideck motion severity index (MSI) and wind severity index (WSI).
    3. Measurement/monitoring of relative wind direction (RWD) and 2min averaged wind speed at rotor height.
    4. New helideck motion status lights are installed on the helideck. The status of the lights is determined automatically by the HMS, as explained below.

    The new procedures for helicopter landing are divided into two phases, and the HMS operates in two corresponding, distinct modes:

    • Pre-landing mode;
    • On-deck mode;


  2. Pre-landing:

    The helideck motion status lights indicate the status of the helideck motion as follows:

    = safe to land (ROLL, PITCH, INCLINATION, HEAVE RATE and MSI/WSI all within limits).
    NB: The light is blue rather than green in order to distinguish it from the green helideck perimeter lights.


    = do not land (ROLL, PITCH, INCLINATION or HEAVE RATE out of limits).

    ROLL, PITCH, INCLINATION and HEAVE RATE are relevant to the touchdown only and the existing limits apply.

    The MSI/WSI is a new scheme and relates directly to the stability of the helicopter while landed on the helideck. Exceedance of the MSI/WSI limit is indicated by the deck motion status lights as follows:


    = Land with caution (MSI/WSI ONLY out of limits). Consider employing revised helideck handling procedures (see separate guidance).



  3. On-deck:

    Under the new scheme, the only parameter of importance after touchdown is the relative wind direction. The trials HMS calculates and monitors the relative wind direction as a function of wind speed once the helicopter’s touchdown heading is entered by the RO (this triggers the switch to ‘on deck’ mode).

    The helideck motion status lights indicate the on-deck status of the helideck as follows:

    ( (●) ) = slow blue flashing - HMS in ‘on deck’ mode, relative wind direction is within limits.


    The relative wind direction is then monitored against the limits that have been defined. Exceedances will be indicated by flashing the helideck motion status lights as follows:

    (((●))) = fast AMBER flashing - relative wind limit approaching. Investigate cause and plan mitigating actions.


    (((●))) = fast RED flashing - relative wind limit exceeded. Carry out planned mitigating actions.



    Note that the relative wind monitoring function is inhibited and no warnings will be generated at wind speeds less than 15 kts.







Alba FSU HMS trial - description - v1 Feb 2015