Top 5 airlines by number of international passengers: United, American, Delta, US Airways, Jet Blue.

FORBES: Report Confirms U.S. Airplanes Are Most Crowded Since WWII Era

Our investigation found that Southwest Airlines, US Airways, Jet Blue and Frontier all pay Aeroman in El Salvador to fix up some of their aircraft.

FORBES: JetBlue Good For A Climb To $7

Airlines were up to, with Southwest gaining 5.9%, AMR Group (which owns American Airlines) up 4.8%, Jet Blue gaining 4.2%, and US Airways up 9.5%.

FORBES: AIG's Plane Leasing Unit Orders 100 Airbus A320neos And 33 Boeing 787s For $11.8BN