Summer air fares climbing as airlines add surcharges

The bad news about summer air fares keeps stacking up like aircraft waiting to land at San Francisco International Airport on a foggy day.

First, airlines hiked fares in response to escalating oil prices. Then they stopped discounting seats as the economy improved and travelers started returning to the skies. Now, carriers are quietly adding surcharges to tickets on peak travel days this summer.

At this point, carriers consider every day this summer to be a peak travel day -- except July 4. Surcharges, levied by American, Continental, Delta, United and US Airways, vary from $10 to $30 per a one-way domestic flight and are typically higher Thursday through Sunday.

They can add up quickly.