2.0 Helicopter Landing Area Design Considerations - Environmental Effects

  2.1.1 The safety of helicopter flight operations can be seriously degraded by environmental effects that may be present around vessels. The term "environmental effects" describes the effects of the vessel, its systems, and forces in the surrounding environment, which result in a degraded local environment in which the helicopter is expected to operate. These environmental effects are typified by structure-induced turbulence, and turbulence/thermal effects caused by exhaust emissions. Controls in the form of landing area availability restrictions may be necessary and should be imposed via the Aviation Inspection Body. Such restrictions can be minimised by careful attention to the design and layout of the vessel topsides and, in particular, the location of the helicopter landing area.

  2.2.1 Guidance for landing area design considerations are given in UK Civil Aviation Authority Paper 2004/02 which should be consulted by designers of helicopter landing areas at the earliest possible stage of the design process and is available through the CAA website (www.caa.co.uk).

  2.2.2 The objective of CAA Paper 2004/02 is to help designers of helicopter landing areas to create topside designs and helicopter landing area locations that are safe and 'friendly' to helicopter operations by minimising exposure to environmental effects. It is hoped that, if used from the outset of the design process when facilities are first being laid out, this manual will prevent or minimise many helicopter landing area environmental problems at little or no extra cost to the design or construction of the vessel.

  2.2.3 All new helicopter landing areas, or modifications to existing topside arrangements which could potentially have an effect on the environmental conditions due to turbulence around an existing helicopter landing area, or helicopter landing areas where operational experience has highlighted potential airflow problems should be subject to appropriate wind tunnel testing or CFD studies to establish the wind environment in which helicopters will be expected to operate. As a general rule the standard deviation of the vertical airflow velocity should be limited to 1.75m/s. The helicopter pilot/operator and Aviation Inspection Body should be informed at the earliest opportunity of any wind conditions for which this criterion is not met in order to allow the appropriate platform availability restrictions/limitations to be defined if necessary.

  2.2.4 Designers of helicopter landing areas should commission a survey of ambient temperature rise based on a Gaussian dispersion model and supported by wind tunnel tests or CFD studies for new build helicopter landing areas, modifications to existing topside arrangements, or for helicopter landing areas where operational experience has highlighted potential thermal problems. When the results of such modelling and/or testing indicate that there may be a rise of air temperature of more than 2°C (averaged over a 3 second time interval), the helicopter pilot/operator and Aviation Inspection Body should be consulted at the earliest opportunity so that appropriate platform availability restrictions/limitations may be applied if necessary.