RE:stone castle campbellI think JET (JETMF) is worth investing in as a speculation.
They have been able to attract experienced management and the ULCC business model is sound.
WestJet certainly represents a potential issue but "airlines within airlines" have not generally proven successful.
Mark Morabito is involved with JET. That's good enough for me. I have a significant investment in his MIN (EXMGF) at an average cost of 35 cents (US) and it's 89 cents today.