First it was lengthy delays caused by storms on the East Coast. Now air travelers are going to have to contend with higher ticket prices.

United Air Lines and Continental Airlines initiated the increases Monday by adding a $10 one-way fuel surcharge for all flights. Fuel prices have been rising steadily for the last three months. A merger between United and Continental is in the works.

American Airlines and Delta Air Lines responded by announcing a $10 one-way fare increase for all flights. (On Tuesday, United and Continental renamed their price hike, also calling it a “fare increase.”)

In the past, such increases were usually matched by other major airlines.