Republic Airways posts 4Q loss on accounting, fuel - Yahoo! Finance

"Republic has been shifting its operations — especially Frontier — toward bigger planes because they are more economical. Fuel costs are spread out over more passengers per plane. At Frontier, Republic got rid of 21 planes with 99 or fewer seats, and added 10 planes with 120 or more seats.

Lots of airlines are getting rid of smaller jets, so they aren't worth as much as they used to be, forcing Republic to write down the value of the smaller planes that it still has."