The U.S. Department of Justice is investigating whether some unnamed major US airlines colluded to drive up airfares by reducing the supply of seats, routes, and flights, reports the Associated Press.

Miami Airport.
Miami Airport.

An investigation may reveal if the airlines were unlawfully coordinating their moves.

AP reports that American Airlines, Delta Air Lines, Southwest Airlines and United Airlines all said they received a letter and are complying. Smaller carriers, including JetBlue Airways and Frontier Airlines, said they had not been contacted as part of the probe.

In the last year, the average cost of domestic US airplane tickets has risen 13%, after adjusting for inflation — which government statistics show is an above-average spike.

Yet rising ticket prices could also be partly blamed on how airlines have been using a perfectly legal method to make it harder to find a cheap ticket.

Delta and Lufthansa have been joining other carriers in pulling their airfares from major travel websites at a slow but steady pace.

The airlines want travelers to buy tickets from their own websites rather than through online or offline travel agencies. In the process, they are making it harder for flyers to comparison shop.

For example, Lufthansa says that, starting in September, it will add a fee of €16 euros to tickets purchased through online or most offline travel agencies instead of through its own website and app. Air France says it is considering a similar move.

In the US, Delta has stopped more than 25 other websites from displaying its airfares, such as CheapOAir,,, Hipmunk, TripAdvisor and Skyscanner.

Hipmunk’s website says, “Delta has made prices and availability only accessible on our partner site,” and it directs consumers to Travelocity.

It’s not about fees, either. Airlines are pulling price and schedule information from sites that refer customers directly to the airline’s websites for zero commission, says the Travel Technology Association, a lobbyist for the travel websites.

Several low-cost airlines, such as Ryanair and Southwest, have long kept their fares to their own websites.

Relying on just one travel site may mean a traveler does not get a full picture of what’s available for fares. Some travelers may conclude that searching more than one website as well as airline’s own websites is the only way to spot the best deal.

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