Although helicopters are not widely utilised at present in the
offshore wind farm O&M activities, they have different operational
characteristics than other marine transportation systems; therefore,
helicopter operations are also considered in the methodology
in addition to conventional transportation systems. The helicopter
specific inputs [1–5] are listed in Table 4. Due to high capital
investment required, offshore wind farm operators generally
charter a helicopter for a certain number of annual flying hours
as the input [1]. The inputs [2–5] display the generic characteristics
of the helicopter. It is assumed that helicopter and CTV
working shifts start at the same time.