He added: “Remember, this is the same management group that (instead of allowing passengers to reap a modest reduction in fares) responded to the F.A.A.’s inability to collect taxes in mid-2011 by gleefully raising base fares to where total out-of-pocket costs were exactly the same (earning a windfall of $28.5 million per day).”

Such behavior is only possible either in an industry with very little competition or one in which members seem to actively avoid it. The cost of air travel has drawn the scrutiny of Senator Charles E. Schumer, Democrat of New York. “At a time when the cost of fuel is plummeting and profits are rising, it is curious and confounding that ticket prices are sky-high and defying economic gravity,” he declared in a statement in December. “The industry often raises prices in a flash when oil prices spike, yet they appear not to be adjusting for the historic decline in the cost of fuel; ticket prices should not shoot up like a rocket and come down like a feather.”

He urged the Justice Department and the Transportation Department to investigate immediately why airline profits are not being passed down to consumers more efficiently. So far, his call for an investigation seems to have gone unheeded. The Justice Department sent a letter to Senator Schumer contending that the merger of American Airlines and US Airways — which it approved contingent upon some divestitures — has led to benefits for consumers through “lower prices and increased service.”

That’s an odd statement because the Justice Department originally sought to block the deal based on evidence that the industry was already seeking to avoid competition. “If, for example, United offers nonstop service on a route, and Delta and American offer connecting service on that same route, Delta and American typically charge the same price for their connecting service as United charges for its nonstop service,” the government found. “As American executives observed, the legacy airlines ‘generally respect the pricing of the nonstop carrier [on a given route],’ even though it means offering connecting service at the same price as nonstop service.”

Senator Schumer, responding to the lack of action in Washington, said in a statement, “The fact that airfares are still at 30,000 feet and climbing, despite the stable gas prices and rising airline industry profits, is extremely troubling, and the federal government has more work to do.”

According to the International Air Transport Association, the industry in the United States is set to post “net post-tax profits” of $13.2 billion in 2015, up from $11.9 billion in 2014. That forecast, however, was based on an average cost of $85 a barrel for Brent crude oil. Today, the price is about $55 a barrel.