Complex sentence: In the North American market, CHC Helicopter was the first operator of the type; in 2012 CHC became the largest operator of the AW139 in the world, operating 44 in search and rescue, emergency medical service and offshore transport missions.
Split into simpler sentences: In the North American market, CHC Helicopter was the first operator of the type. In 2012, CHC became the largest operator of the AW139 in the world, at that point operating a fleet of 44 in search and rescue, emergency medical service and offshore transport missions.