Clickable banner usually located below the fold.
Banner above the fold.
Carousel banner on home page.
Banner below the fold.
...
Brand presence throughout flight reservation and purchase process.
Banner on airline web site content pages.
Banner on web/print boarding passes.
Banner confirmation email including traveler purchase details.
Banner on bag tags given to passengers.
Banner in email sent to airline database and travelers to encourage their next trip.
Advertising space on digital boarding pass.