Mountain flying is a challenge for any skilled pilot.
Add in white cloud and snow covering the ridge lines and you have a potentially very dangerous environment for flying.
Pilots from 27 Squadron Royal Air Force are in Norway testing their mettle with some nerve-wracking navigation in the country's mountains, in temperatures falling to -25.
It's the first time the squadron has deployed to Norway and for some pilots it's their first time flying in such harsh conditions.
They're learning to perform 'pinnacle' landings - a tactic for quickly embarking troops from rough terrain.
Once 27 Squadron returns from the training crews will be placed on high readiness for operations around the globe.
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