Earlier this week, we saw some significant airfare hiking activity from U.S. domestic airlines: United Airlines, for example, initiated a $40 roundtrip hike in a small number of markets (but mainly in Chicago); that hike, however, is currently falling apart, although it was matched by American Airlines.

In a separate move, United began a laddered hike of $2 to $10 roundtrip, on routes flown by low-cost carriers. This hike is based on mileage: the $2 roundtrip hike was applied to routes under 500 miles; $6 roundtrip hike on routes between 500 and 1,000 miles; and $10 roundtrip hike on routes over 1,000 miles. So far these hikes have been matched by all major airlines, including Southwest Airlines.

It’s also clear that it is important to the airlines to keep sales momentum going for domestic tickets by filling some early summer seats at discount prices except on peak days (and note that “peak travel day” surcharges are in play this summer and please see the surcharge charge for more details), and to that end we saw a 3-day sale from AirTran which included flights through the summer travel period and beyond; this sale, now expired, was widely matched by other carriers.