One of the most popular features of the old Farecast travel search engine has taken its last voyage.

MIcrosoft, which paid $115 million for the Seattle-based company six years ago this month, has turned off the price prediction tool that informed travelers of the likelihood that airfare prices would rise or decline.

When Farecast’s price prediction technology launched in 2004, it grabbed headlines since it was one of the first and most understandable consumer Internet applications of “big data,” a term that was not really in use. At the time, Farecast founder and former University of Washington computer science professor Oren Etzioni dismissed critics when he said that “computers are comfortable sifting through large volumes of numbers to find patterns.”

Those patterns were used to tell travelers whether a future flight between Boston and Seattle or thousands of other combinations was about to increase or decrease in price.

Reached this morning, Etzioni said he was sad to learn that the price prediction tool was being turned off, calling it one of the “most distinctive features of Bing.”

Etzioni, who now leads Microsoft co-founder Paul Allen’s Artificial Intelligence Institute, said that many travel technology and business experts left Bing’s team. In addition, he said that Bing was “outflanked” by Google when the search giant purchased ITA Software. While Microsoft and others attempted to block that sale, Etzioni said that “Bing didn’t want to pay Google for the data required to power Farecast.”

“So, we end up with Bing travel as a thin veneer that redirects users to Kayak, while Google innovates with Google.com/flights, which I now use all the time,” said Etzioni. “Google 1, Bing 0.”

In fact, Kayak introduced a similar price prediction tool for its travel search engine last year.

This isn’t the first time that Etzioni has voiced displeasure with Bing’s progress, noting at an event in Seattle last year that he was disappointed with how little has come out of the search engine in recent years.

Here’s the statement Microsoft provided to GeekWire on the rationale behind the end of the price prediction service.

“Bing is no longer offering Price Predictor, but remains committed to delivering a comprehensive travel experience that gives people great travel information including flight and hotel search functionality. In addition to Bing.com/travel, travelers can find relevant travel information in new and visually compelling ways through the Bing Travel app and Bing Smart Search for Windows 8.1 and Bing Maps. As to why price predictor was turned off — It was a business decision to focus resources on areas where we feel there are the greatest opportunities to serve travel needs.”

(Hat tip to Tnooz)