The Feb. 9 flight used 22,000 gallons of fuel to carry the passengers on the trans-Atlantic route, a decision Friends of the Earth said was environmentally irresponsible, The Telegraph reported Wednesday.

"Flying virtually empty planes is an obscene waste of fuel," said Richard Dyer, Friends of the Earth's transport activist. "Through no fault of their own, each passenger's carbon footprint for this flight is about 45 times what it would have been if the plane had been full."

American Airlines officials said it was forced to cancel one of its four daily fights from Chicago to London. While it was able to place nearly all of the canceled flight's passengers on other flights, five couldn't be accommodated.

Then there was the London-to-Chicago flight to consider.

Canceling the flight "would have left a plane load of west-bound passengers stranded at London Heathrow who were due to fly back to the U.S. on the same aircraft," an airline spokesman said.