Air Sol is an airline in Grand Theft Auto IV. An online article on Liberty Tree's website mentions that an Air Sol flight has 212 passengers onboard, 212 being a reference to the area code in New York City. On the Rockstar Games Social Club website, a Air Sol plane ticket can be found for Niko Bellic to go from Liberty City to San Andreas, which some have speculated that this might be a clue to Niko is going to appear in Grand Theft Auto V, however Niko hasn't been confirmed yet.
The name Air Sol might have been chosen because, when spoken quickly, it sounds like "arsehole", which fits with the suggestive slogans and the logo that resembles an anus. Several of their advertisements feature innuendos of anal sex.