American Airlines, the world’s second-biggest carrier, will charge $50 to check a second bag on most international flights to help increase revenue as travel declines and fuel prices rise.

The change, effective for tickets bought starting Sept. 14, applies on trans-Atlantic flights to, from or through India, England, Belgium, France, Germany, Ireland, Italy, Spain and Switzerland and to U.S. territories.

Those flights represented about 16 percent of American’s capacity this year through July.

The checked-bag charge for the AMR Corp. unit is its first on international routes, and follows increases last month in the fee to check bags on domestic flights.

U.S. carriers are trying to boost revenue as the recession damps travel, airlines cut fares and fuel prices rise.

“The cost of doing business continues to rise as both the economy and the price of fuel remain volatile,” said Tim Wagner, a spokesman for Fort Worth, Texas-based American. “Our new checked-bag policy gives us a better opportunity to cover these expenses.”

American’s passenger traffic fell 9.5 percent this year through July.

Starting with tickets bought Aug. 14, American increased to $20 from $15 the charge to check one bag and to $30 from $25 the fee for a second bag on U.S. flights.

American’s most frequent fliers, those in premium-class cabins and U.S. military personnel are exempt from the bag fees.

Virgin America Inc., the carrier partly owned by U.K. billionaire Richard Branson, today said it would raise fees to check bags by $5 to $20. The changes take effect today for travel on or after Sept. 10.