With helicopters, an example—and this has been in place in both jurisdictions ahead of the recent Transport Canada regulations—is that of restricting flights over sea states where safe ditching could not occur. In other words, a sea state has to be below a certain threshold in order for flights to occur. Those limits were worked out between the boards and the operators, and they are now ingrained in legislation for Transport Canada.
On December 2nd, 2013. See this statement in context.