MINNEAPOLIS (AP) — Delta Air Lines said a glitch that appeared to show different airfares to frequent fliers happened because it was trying out a new company to power flight searches on its website.

The airline has taken heat from customers after reports that people who logged into its website with their frequent flier number were offered higher fares than those who searched anonymously. Frequent fliers are an airline’s most-valued customers, and the idea that they were asked to pay more has rankled travelers.

Late Friday afternoon, the Transportation Department said it is “looking into the Delta pricing issue.” Spokesman Bill Mosley refused to elaborate.

The airline offered is first detailed explanation of what went wrong in an interview with The Associated Press Friday.

Delta and other airlines use third-party companies such as Google’s ITA Software to deliver results when customers search for flights. Those search providers sift through all the available seats, possible connecting flights and different fares to show flight options to customers.

Delta was thinking about switching search providers, so starting on April 20 it ran a side-by-side experiment, Bob Kupbens, the airline’s head of e-commerce told The Associated Press. People who logged in with their frequent flier number saw results from the airline’s current search provider. People who searched anonymously got results from the experimental provider. Delta declined to name either company.

“We don’t want to take all of our best customers, who we care the most about, and put them immediately onto a new search engine,” Kupbens said. Ultimately, he said, the airline hoped the switch in search companies would provide travelers with faster and more-relevant search results.

The problem was that one of the search engines included flight possibilities that the other one didn’t, Kupbens said.

For example, one search might include a cheaper flight with a less-desirable connection, while the other one didn’t include that option. A customer would see that one result had cheaper options than the other.

Kupbens said the airline never sold customers the same exact roundtrip flights at different prices.

“To be clear, we never — and couldn’t have, based on the technology — we never sold the exact same itinerary for a different price. So what customers were seeing was a difference in search results, not a different price for the same itinerary,” he said.

Delta ended the side-by-side test on May 9.

Kupbens said the problem was not with the experimental search provider, but with the way Delta asked it to assemble its results. The new search provider is still being considered for a switch, he said.

The airline industry has long been criticized by customers for a lack of transparency in its pricing. Airfares change from hour to hour and it’s often not clear how many seats are left for sale on a specific flight.

This latest snafu just feeds into customers’ fears that they aren’t always getting the best price.

“When it comes to prices, it’s time for airlines to start telling the whole truth,” Charlie Leocha, director of the Consumer Travel Alliance said in a statement. His group and the Business Travel Coalition on Friday called for the Department of Transportation to review price-display practices for airfares and the growing number of fees for services such as checked baggage and seat assignments.

Shares of Atlanta-based Delta Air Lines Inc. closed down 28 cents, or 2.7 percent, at $10.13.

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Mayerowitz, who reported from New York, can be reached at http://twitter.com/GlobeTrotScott .

SAN FRANCISCO (AP) — Google is introducing a new tool, designed to make its search engine smarter.

The new feature debuting Wednesday draws from a Google-built database of more than 500 million people, places and commonly requested things to provide a summary of vital information alongside the main search results.

Google Inc. spent the past two years poring through online encyclopedia Wikipedia, the CIA Factbook and other sources to expand a database of 12 million items that it picked up as part of its 2010 acquisition of Metaweb.

The information warehouse, which Google calls a “Knowledge Graph,” is an attempt by the Internet’s dominant search engine to provide answers as quickly and concisely as possible so users don’t have to sift through a hodgepodge of Web links displayed on the main results page.

The nuggets of information will appear in boxes to the right of the main search results. Google will gradually roll out the feature to its logged-in users in the U.S. during the next few days before extending it to a wider audience.

The changes come as one of Google’s biggest rivals, Internet social networking leader Facebook Inc., prepares to complete an initial public offering of stock that is dominating the technology spotlight. The Knowledge Graph’s unveiling comes a week after the second-largest search engine, Microsoft Corp.’s Bing, announced an overhaul that will highlight more information mined from Facebook — insights that typically don’t show up in Google’s results.

The Knowledge Graph will work in different ways.

If a person enters a search request, such as “kings,” that can be interpreted in several ways, Google will now display a box on the right side of the page listing several other options, such as the Los Angeles Kings hockey team, the Sacramento Kings basketball team and the Kings TV show. Clicking on any of these choices will deliver results exclusively devoted to that topic.

Queries on specific people or places will generate thumbnails that list key statistics about the topic. Google bases its assumption on what people are most likely to want to know on an analysis of past search requests.

Google is hailing the Knowledge Graph as an important step in Internet search’s evolution. The company is trying to make the difficult transition from merely presenting a list of Web links to delivering the kinds of responses that people expect when they pose a question to an expert.

“This used to be the stuff of dreams because we didn’t really know how to accomplish it,” said Amit Singhal, a Google fellow who has been studying search for 22 years. “The dream has always been to understand things like you and I do, so this this really feels like a sea change.”

The Knowledge Graph also will help address another problem vexing Google.

As websites seeking traffic have learned to manipulate commonly requested search terms, their links have been appearing more frequently on the first page of Google’s results, even though they might not have the most relevant information. Google periodically tries to remove the rubbish by tweaking its ranking system, only to have websites figure out new ways to outfox the search formula.

If the Knowledge Graph works like it’s supposed to, it will give visitors less reason to leave Google’s website.

Although Google says that isn’t its main objective, anything that gives people a reason to hang around for longer periods, and perhaps enter more search requests, promises to help the company make more money. Google distributes ads all over the Web, but it reaps its highest profit margins from commercial links that are clicked on its own website.

Anything that keeps people on Google longer is likely to amplify complaints that the company is more interested in promoting its own services than pointing visitors to other helpful Internet destinations.

Singhal doesn’t see it that way. “As we answer more of our users’ questions, we save them time,” he said. “Time is the only quantity that we can’t make more of. When people save time, people search more. The Web gets more traffic and all boats rise.”

SAN FRANCISCO (AP) — Google is introducing a new tool, designed to make its search engine smarter.

The new feature debuting Wednesday draws from a Google-built database of more than 500 million people, places and commonly requested things to provide a summary of vital information alongside the main search results.

Google Inc. spent the past two years poring through online encyclopedia Wikipedia, the CIA Factbook and other sources to expand a database of 12 million items that it picked up as part of its 2010 acquisition of Metaweb.

The information warehouse, which Google calls a “Knowledge Graph,” is an attempt by the Internet’s dominant search engine to provide answers as quickly and concisely as possible so users don’t have to sift through a hodgepodge of Web links displayed on the main results page.

The nuggets of information will appear in boxes to the right of the main search results. Google will gradually roll out the feature to its logged-in users in the U.S. during the next few days before extending it to a wider audience.

The changes come as one of Google’s biggest rivals, Internet social networking leader Facebook Inc., prepares to complete an initial public offering of stock that is dominating the technology spotlight. The Knowledge Graph’s unveiling comes a week after the second-largest search engine, Microsoft Corp.‘s Bing, announced an overhaul that will highlight more information mined from Facebook — insights that typically don’t show up in Google’s results.

The Knowledge Graph will work in different ways.

If a person enters a search request, such as “kings,” that can be interpreted in several ways, Google will now display a box on the right side of the page listing several other options, such as the Los Angeles Kings hockey team, the Sacramento Kings basketball team and the Kings TV show. Clicking on any of these choices will deliver results exclusively devoted to that topic.

Queries on specific people or places will generate thumbnails that list key statistics about the topic. Google bases its assumption on what people are most likely to want to know on an analysis of past search requests.

Google is hailing the Knowledge Graph as an important step in Internet search’s evolution. The company is trying to make the difficult transition from merely presenting a list of Web links to delivering the kinds of responses that people expect when they pose a question to an expert.

“This used to be the stuff of dreams because we didn’t really know how to accomplish it,” said Amit Singhal, a Google fellow who has been studying search for 22 years. “The dream has always been to understand things like you and I do, so this this really feels like a sea change.”

The Knowledge Graph also will help address another problem vexing Google.

As websites seeking traffic have learned to manipulate commonly requested search terms, their links have been appearing more frequently on the first page of Google’s results, even though they might not have the most relevant information. Google periodically tries to remove the rubbish by tweaking its ranking system, only to have websites figure out new ways to outfox the search formula.

If the Knowledge Graph works like it’s supposed to, it will give visitors less reason to leave Google’s website.

Although Google says that isn’t its main objective, anything that gives people a reason to hang around for longer periods, and perhaps enter more search requests, promises to help the company make more money. Google distributes ads all over the Web, but it reaps its highest profit margins from commercial links that are clicked on its own website.

Anything that keeps people on Google longer is likely to amplify complaints that the company is more interested in promoting its own services than pointing visitors to other helpful Internet destinations.

Singhal doesn’t see it that way. “As we answer more of our users’ questions, we save them time,” he said. “Time is the only quantity that we can’t make more of. When people save time, people search more. The Web gets more traffic and all boats rise.”