By default, a helicopter can only work during daylight hours.

You can toggle the daylight restriction off in the helicopter's settings

In order for the daylight restrictions to work properly, it is important that you set the correct time zone for your wind farm. This is done via the Build > Strategy tab:

Once you have set the time zone, the helicopter will be restricted to only fly during daylight.

When running a simulation, the Shoresim engine uses the time zone and the latitude and longitude of the helicopter's home base to calculate the sunrise and sunset times for that specific location. This allows for accurate daylight hour calculations for any location globally, even for different locations within the same time zone.