Complex sentence: Citywing (a trading name of Citywing Aviation Services Limited) is an Isle of Man-based company that sells seats on scheduled air flights operated under charter from UK and EU-registered airlines Van Air Europe and Links Air.
Split into simpler sentences: Citywing (a trading name of Citywing Aviation Services Limited) is an Isle of Man based company which sells seats on scheduled air flights. Citywing does not operate the flights itself and the routes are operated under charter from UK and EU registered airlines Van Air Europe and Links Air.