During my middle years military flying on Puma HC1 in the NATO environment, it was widely understood that to fly in the NOE exercise scenario, the RIGHT HAND RULE was paramount. In most cases the procedure ensured that we avoided each other during circular troop lift flights in the narrow Norwegian valleys. That is until one worthy flew left hand around a blind corner, pulled hard away from the head-on conflicting traffic and flicked toward the cliff. Luckily, he survived together with his troops.