http://www.guardian.co.uk/business/2008/apr/21/theairlineindustry.useconomy

excerpt;
"Continental's fleet of 41 Boeing 757-200 aircraft are an average of 11 years old. According to Boeing, the planes have a range of 3,900 nautical miles which, in normal conditions, is comfortably above the 3,014 nautical miles for an average flight between London and New York.

But holding patterns at airports add to fuel burn and certain European destinations are more of a stretch - a flight from Barcelona to Newark is 3,338 nautical miles and the US government revealed that Continental's pilots on this route declared minimum fuel 23 times last year."