Introduced to the market in 2012, Pratt & Whitney Canada's PT6A-140 turboprop series has achieved broad acceptance in utility and agricultural markets for both forward-fit and retrofit application on a variety of aircraft.
Ultimately you're going to have to upgrade to ADS-C and CPDLC to operate above FL 280 in most oceanic airspace anyway (e.g., by Jan. 1, 2020, in the North Atlantic), but here's what you're missing out on now in the North Atlantic Track System.
