Delta Airlines matched Northwests airfare sale in this evenings 8:00pm EDT update. They filed 15,472 airfare reductions with an average cut of $93 in the top 1200 city pairs.

Deltas price drops change 220 top markets. Airfare decreases apply to walk-up, 3-day, 7-day, 14-day and 21-day advance purchase.

Continental and United also joined in on the airfare sale, although not as broadly as Northwest and Delta.

So far American and US Airways have not elected to join in on Northwests airfare sale.

This evening in the 8:00pm Domestic U.S./Canada airfare feed, Northwest Airlines filed a 15% fare sale across 4,308 city pairs. The average reduction across 19,617 airfares was $93. The sale applies primarily to mid-sized markets. Northwests hub airports of Detroit and Minneapolis are not included in the sale.

The sale applies to walk-up, 3-day, 7-day, 14-day and 21-day advance purchase airfares. Tickets must be purchased by 22-Feb and travel completed by 6-June.

In last evenings 8:00pm U.S./Canada airfare feed Midwest airlines increased 1,291 airfares by $5 each-way affecting 549 top city pairs. This includes most of the Midwest Airlines route system.

Delta Air increased approximately 37,000 airfares by $5 each-way in this evenings 8:00pm EDT airfare feed.

This is a system-wide increase for U.S and Canadian city pairs and is applicable to walk-up, 3-day, 7-day, 14-day and 21-day fares.

This increase is the third attempt to raise airfares in 2007 and follows Deltas successfully spurning US Airways hostile merger bid.

The previous two airfare increases in 2007 were led by United Airlines.