How dow I get to Stephenville NL by air? I'm from Saint Louis Missouri in the US.I realize some sort of drive may be needed once in NL.
There are a couple of options. Both Air Canada and WestJet fly into Deer Lake (YDF) about 90 minutes drive from Stephenville. But routing via Air Canada would probably be simpler with less stops (ie stopover in Toronto, then direct to Deer Lake. WestJet will take you from STL to LaGuardia, then Toronto, then Deer Lake.
Your other option is to check with Provincial Airlines, they may have flights into Stephenville from either Deer Lake or St. John’s (YYT), but not cheap.
Most people going to the west coast of Newfoundland choose to fly into Deer Lake airport rather than Stephenville. If you need to fly into Stephenville for whatever reason, then you could try PAL as janidd mentions, and Porter has Halifax-Stephenville flights, with the same aircraft on the run from Halifax to Toronto's island airport.