There have been several requests today to rundown the airfare hike from last week and I just spent about an hour reviewing this the U.S. domestic airfare distributions over the weekend and today.

In tracking over 50 airfare hike attempts in the past 3 years I have never come across a hike like this one.

Both Delta/Northwest and Southwest initiated hikes separately last Thursday night of $10 roundtrip ($5 one-way) and it appears that everyone other than Continental has mostly matched the Southwest overlapping routes, but none of the legacy airlines are participating in the much broader Delta/Northwest hike.

The reason this is odd is that typically this would force Delta/Northwest to rollback their non Southwest route hikes by the end of the day Monday, with the hike essentially fizzling - however at this point they haven’t rolled back, essentially leaving them on an island for the moment.

In the midst of the hike there are some off-peak sale airfares in the marketplace from AirTran and Southwest that further obscure the airfare landscape.

The bottom line is that we’ll need another day of activity to get a clearer picture on the final disposition of this third airfare hike attempt.

After reviewing the domestic airfare distributions from last night and this morning we note the following activity:

• Delta, Southwest, Alaska, Midwest, Frontier ($10 roundtrip [$5 oneway] increase bulk of route system)
• US Airways selective matching
• United Airlines dabbling in some limited matching
• American and Continental on the sidelines so far

The Southwest increase of 5 one-way was on mid/long haul routes and $2 one-way on short haul routes (outside of sale fares).

It is very difficult to get an exact read on this hike as there was some late week off-peak travel discounting that is mixed in with the increase activity.

Typically we will know if the hike attempt sticks by Monday afternoon.

It appears at this point that the hike has a very good chance of surviving - I have never seen an airfare hike in 4 years fail when Southwest Airlines was in the mix.

Tonight at 8pm EST Delta Air Lines (along with Northwest) initiated a domestic airfare hike of $10 roundtrip ($5 each way) across the bulk of its U.S. route system.

This domestic airfare hike marks the 3rd attempt in the past 6 weeks with the past 2 tries successfully sticking.

On yesterdays Q2 earnings call American Airlines CEO Gerard Arpey said he did some quick calculations on the back of an envelope and “figured that airlines needed about $17 more per one-way customer in the quarter to break even.”

If this domestic airfare increase sticks it would mean an increase of $20 to $25 each way domestically for the legacy airlines in the past 6 weeks. However this increase does not include international tickets nor the widely matched off-peak late summer/fall airfare domestic sale initiated by Southwest earlier this week.

Starting this past November through late May of this year airfare prices had been in a free fall, in June domestic airlines popped their chutes with a couple of airfare hikes — the big question is whether or not their is a hole in the canopy as demand in tough economic times is impossible to predict.