United Continental Holdings Inc. has awarded millions of frequent flier miles to hackers who have uncovered gaps in the carrier’s web security, in a first for the U.S. airline industry.

United confirmed with Reuters that it has paid out two awards worth one million miles each—meaning dozens of free domestic flights on the airline. United did not confirm tweets from individuals who say they have been paid smaller awards as well.

The Chicago-based carrier has hoped to trailblaze in the area of airline web security by offering “bug bounties” for uncovering cyber risks. Through the program, researchers flag problems before malicious hackers can exploit them. The cost can be less than hiring outside consultancies.

Three of United’s competitors declined to comment on bug bounty programs. A fourth was not immediately available for comment.

Trade group Airlines for America said in a statement that all U.S. carriers conduct tests to make sure their systems are secure.

United unveiled the approach in May, just weeks before technological glitches grounded its entire fleet twice, underscoring the risks that airlines face. One incident locked the airline out of its reservations system, preventing customers from checking in, and another zapped functionality of the software United needed to dispatch its flight plan.

“We believe that this program will further bolster our security and allow us to continue to provide excellent service,” United said on its website, declining additional comment.

Jordan Wiens, a researcher focused on cyber vulnerabilities, tweeted last week that he received United’s top reward of one million miles for exposing a flaw that could have allowed hackers to seize control of one of the airline’s websites.

“It’s really interesting that United did what they did,” he said in an interview. “There actually aren’t that many companies in any industry outside of technology that do bug bounties.”

Wiens said it was normal for large companies such as United to have bugs in their websites.

Terms of the agreement prohibit Wiens from disclosing the bug he discovered. The terms also required that Wiens reveal the supposed problem to United without trying to exploit it, meaning he does not know how much information he could have accessed or manipulated.

Beyond the bounty, United said it tests systems internally and engages cybersecurity firms to keep its websites secure.