BEagle made a good point about the northern route in winter. One of my last jobs in maritime was to brief the SAROp cover for a Leopard Trail. To give a flavour of the hazard we planned to join the Jaguar crews at Marham for a mass brief. We never made it. We diverted to Waddington and were snowed in.
For the flight across we carried a mix of additional dinghies - for a Victor crew and a Jaguar - and also Containers Land Equipment as there was almost ad much land/ice than sea between Colt and Gander.