The National Weather Service is changing its procedures for sending out radio messages after an operator mistakenly sent out a radiological hazard warning yesterday while trying to transmit the weekly emergency broadcast test.

"Even if this happens once every 10,000 years, you don't want it to happen again," said Jeff Powell, weather service lead forecaster.

Some radio stations caught the error before putting the message on the air, state civil defense spokesman Dave Curtis said.

But many didn't, and the message also appeared as a crawler on Hawai'i televisions. At least 50 people called civil defense after hearing or seeing the warning about 11:30 a.m. yesterday.

A radiological hazard warning is sent out when radioactive materials have been released. Powell said the warning appears just below the emergency broadcast test message on a scroll-down menu in the software that the weather service uses to transmit messages to stations. The software has been used for at least five years.

Powell said once the message in the software is selected, the operator is asked to confirm that the message should be sent out.

But that fail-safe did not work yesterday.

Powell could not remember an error of this kind ever happening before. In January, the weather service accidentally sent out a tsunami warning. But at the time a tsunami watch was already in effect and a warning was anticipated.

The warning was quickly rescinded.

To make sure an incorrect message is not sent out again, Powell said NWS will require two people to oversee message transmissions.

Technicians will also rearrange the menu bar in the weather software to make sure the emergency test message does not fall near any other warnings. The weather service has dozens of messages to choose from, many of which appear only on weather radio.

Curtis said civil defense officials will be talking with the weather service to make sure the changes are enough to prevent future errors.

Emergency messages, including warnings and watches, are transmitted by the weather service to the state civil defense agency, whose computers then automatically send them to radio and television stations. Once the messages get to stations, an operator must manually play the message or decide not to play it.

Reach Mary Vorsino at mvorsino@honoluluadvertiser.com.