Megabill for fuel

Fuel is the top operating expense for Northwest Airlines. The carrier has raised fares, but it's unable to pass along all its increased fuel costs to customers. If oil stays at much higher levels and averages $104 a barrel this year, Northwest could pay $800 million more for fuel than it anticipated.

Price of oil per barrel Total cost

2007 actual fuel bill $72 $3.7 billion

2008 estimated fuel bill $88 $4.4 billion

2008 potential fuel bill $104 $5.2 billion