JUNEAU, Alaska >> A third-party vendor is being blamed for a mistaken tsunami alert broadcast on Alaska TV and radio stations last month.

Dennis Bookey, co-chair of the Alaska State Emergency Communications Committee, said that this and similar incidents suggest the format of the National Weather Service’s internal testing system for tsunamis should be reviewed.

Bookey’s comments came in a written account dated 10 days after the errant alert was broadcast on May 11. It was provided this week to The Associated Press by Jeremy Zidek, a spokesman for Alaska’s emergency management division.

Zidek said improvements are being made to the Emergency Alert System, and in this case, updated codes were not recognized.

According to Bookey, the vendor’s weather processing server failed to recognize the tsunami warning as a test. He said in an interview today that the software coding issue was corrected after it was discovered.

The system is complex, but not perfect, he said. And incidents like this, while rare, can hurt the credibility of the system, he said.

He cited three similar incidents this year, including an errant message received by users of the popular AccuWeather app along the East Coast, the Gulf of Mexico and the Caribbean.

In those cases and in Alaska, the Tsunami Warning Center, which is part of the National Weather Service, sent out a message that “says it’s the real thing and a test.” The information identifying it as a test has to be read by software, he wrote.

That doesn’t take the vendor off the hook, he said. But it lends credence to calls to review the formatting used by the weather service, he said.

“Maybe there isn’t any way to change it, but I think a review would be just in everybody’s best interest,” he said.

Jonathan Porter, vice president of business services for AccuWeather, said his organization also has asked the weather service to review how test messages are encoded.

“Many of the tests may be OK, but if there’s an issue with the encoding and the format of it, then it results in the product potentially being mischaracterized as a valid warning message and distributed,” he said.

Susan Buchanan, a spokeswoman for the National Weather Service, said in an email today that the agency conducts monthly tests to uncover potential coding problems and works with vendors to resolve any.

Thousands of vendor systems appropriately decode tsunami tests each month, she said. Before the recent incidents, the last time there was an issue was in 2014, she added.

Causes of the false alarms this year varied, she said. In one case, the agency inadvertently re-used a number that prompted a vendor to interpret the test as real, while in other cases, third-party software incorrectly processed the test message, she said.

On the day of the Alaska incident, Buchanan said the test message was properly coded but somehow re-transmitted in an abbreviated format, which stripped the test coding and caused activation of the Emergency Alert System. She said today that the statement, based on an initial early review, was incorrect.

She said the agency later found that wasn’t the root cause when Alaska officials notified the agency that a vendor failed to recognize the test message as a test.