Washington ? Nearly a week after 4,400 mechanics and aircraft custodians walked off the job at Northwest Airlines Corp., the airline said its operations were steadily improving.

“We have run a reliable airline. We have met our customers’ needs,” Doug Steenland, Northwest’s president and chief executive, said in an interview Friday. “That was our goal, and we met our goal in that regard.”

At the same time, Northwest executives said that, because of increased fuel prices, the $1.1 billion that the airline was seeking from its workers is now too little, and the airline may have to increase its sought-after target.

This past spring, Northwest, the nation’s fourth-largest airline, said it would need $1.1 billion in annual concessions from its unions. At that time, fuel prices were in the mid-$40-a-barrel range. This week, oil prices hovered around $68 a barrel. The increase represents an extra $900 million a year in fuel prices for Northwest.