In the “Aviation Blogs” topic of the “Notable Activity” forum, damiross noted that Spirit Airlines is a privately owned airline. That is, shares are not traded on the stock exchanges.
Google Finance reports on Spirit:
“Founded in 1969 by entrepreneur Ned Homfeld, Spirit began as a ground transportation company and expanded into charter flights. The airline provides scheduled and chartered passenger service to 15 destinations using a fleet of MD-80s, which it is replacing with Airbus jets. A cash infusion of $125 million from Oaktree Capital Management in 2004 will allow Spirit to expand its fleet; it also gives Oaktree a 51% stake in the airline.”
I know that Midwest Express was also originally a private airline.
“Midwest Airlines began life in 1948, when Kimberly-Clark Corporation began providing air transportation for company executives and engineers between the company’s Appleton headquarters and their mills.”
Can anyone add some other private airlines (no stock traded) to the list?