And United is keen on holding onto its dominant position. Soon it will have TV, radio, and online ads highlighting the features that Southwest lacks: assigned seats, Economy Plus (economy with more legroom) and first class.
"We want to show our Denver customers how United is different and better than our newest competitor," said United spokeswoman Robin Urbanski.
Although the ads would seem pretty serious because they're aimed directly at a single airline, I bet they'll work, since United is dominant in Denver - more routes, better service. In defense, however, Southwest has launched a campaign of its own announcing its low fares.