When you look carefully into the map, you'll find that the LS airport is actually an INTERNATIONAL airport.
International airports mean that planes are not travelling just inside the country/city...
This may explain where the business jets go because the military airport(Fort Zancudo) and the airport in the Grand Senora Desert seems not the proper destinations for jets. Maybe planes can go to some area that's not shown in the leaked map?
Comment to talk about your ideas on it and consider the possibility to travel to area that's not shown in the leaked map. Thanks!
Full Map Source: http://gtaforums.com...strategy-guide/