For savvy seekers, the online hunt for cheap airfare can offer the thrill of discovery. But for many, the array of choices is dizzying.

Airlines have created innumerable ways for people to book travel, at wide-ranging prices and through a bounty of channels. But these new opportunities also breed new ways to dupe consumers, creating frustration and outrage among travelers.

And that has left airlines and independent travel websites accusing one another of unfair business practices.

In October, the federal government opened an "exploratory" investigation into the situation through the lens of consumer rights and protection. The U.S. Department of Transportation solicited feedback from industry, consumer advocates and the traveling public on whether airlines are fair in how they distribute and market flights to independent, third-party websites.

That formal inquiry is still open for public comment until March 31, but resolution could be delayed by the change in presidential administrations and the complex picture that has emerged from the feedback so far.

"We don't know what the Trump administration will do, but we certainly hope he takes up this mantle of consumer protection," said Emily Cullum, spokeswoman for Travel Tech, the trade group representing online travel sites.

Nearly half of all travelers who book flights online use third-party travel websites for side-by-side flight comparisons, according to a Travel Tech study. But airlines, for various reasons, have gradually restricted the amount of information they give to these websites.

Some advocates said this is an unfair business practice that is hurting consumers who may not realize the search results omit certain carriers. Airlines argue it's their flight information and they can do what they want with it.

"We continue to believe that airlines, like all other private businesses, have the right to sell their product where and how they choose," Vaughn Jennings, spokesman for Airlines for America, the lobbying group for U.S. airlines, said in an e-mail. "It is inappropriate for the government to interfere in the commercial relationship between airlines and their distribution partners."

The two types of flight aggregator websites most commonly used are online travel agencies, called OTAs, and metasearch sites. OTAs, such as Expedia and Travelocity, present flight times and fares from multiple airlines with the option to book itineraries. Metasearch sites, like Kayak and Google Flights, simply display various flights that fit a trip's parameters and then connect users directly to the airline's website for direct booking.

The advantages for consumers are clear: a quick overview of the airlines flying a particular route, an idea of how much it will cost and a slick way to build an itinerary that may rely on different carriers throughout the journey.

Of course, it's not that simple. Some bad actors have spoiled those benefits with scams that take advantage of consumers.

Delta Air Lines, which accounts for 71 percent of the traffic at Minneapolis-St. Paul International Airport, has been a vocal critic of these bad actors, calling out deceptive practices and forbidding certain sites from displaying Delta's flight information.

For instance, the DOT slapped online travel agency CheapOair with a $185,000 fine in 2015 for misleading consumers into believing their flights were nonstop when they actually involved one or more stops. Delta said these types of bad actors create headaches for passengers, which tarnishes the airline's reputation. The airline has also ended its relationship with metasearch provider TripAdvisor and many others.

Southwest Airlines has never allowed third-party sites access to their flight information. The airline's customers visit its site directly to compare flights. Delta said it maintains relationships with the majority of these sites. A Delta spokeswoman said, "The relationships between airlines and online travel agencies and metasearch sites must be based on a mutual respect of the brands and products."

Consumer-protection groups and associations representing the OTAs say the airlines have used a few cases as an excuse to further prod consumers to book directly through their own websites, potentially minimizing competition while the airlines save money, bypassing referral and commission fees incurred through a third-party vendor.

Travel Tech often highlights the consolidation within the airline industry, with four carriers controlling 80 percent of the U.S. market, as a reason these independent sites can bring so much value to the consumer. But the online travel sites have consolidated as well and aren't always upfront about the limitations of their data.

"The third-party sites and metasearch companies should also be honest and tell the consumers that they don't have the full story either," said George Hobica, founder of the fare alert website Airfare Watchdog.

The Trump administration has signaled an intent to slash government regulations, and the airline trade group said it shouldn't back new ones that affect the relationship between them and the online sellers. But Trump has also presented himself as a populist leader concerned about the average American's pocketbook.

"I think this is an important story because a lot of consumers aren't aware that they aren't getting the full picture," Hobica said.

Kristen Leigh Painter • 612-673-4767