The cockpit voice recorder data on the Alaska Airlines Boeing 737 MAX 9 jet which lost a panel mid-flight on Friday was overwritten, U.S. authorities said, renewing attention on an industry call for longer in-flight recordings.

National Transportation Safety Board (NTSB) chair Jennifer Homendy said on Sunday no data was available on the cockpit voice recorder because it was not retrieved within two hours - when recording restarts, erasing previous data.

The U.S. requires cockpit voice recorders to log two hours of data versus 25 hours in Europe for planes made after 2021.

The International Civil Aviation Organization (ICAO) has since 2016 called for 25-hour recording on planes manufactured from 2021.

"There was a lot going on, on the flight deck and on the plane. It's a very chaotic event. The circuit breaker for the CVR (cockpit voice recorder) was not pulled. The maintenance team went out to get it, but it was right at about the two-hour mark," Homendy said.

The plane's flight data recorder and cockpit voice recorder were sent to NTSB labs on Sunday to be read but no voice data was available, she said.

DEBATE WITH FAA

The NTSB has been vocal in calling for the U.S. to extend its rule to 25 hours. The U.S. Federal Aviation Administration (FAA) a month ago said it was proposing to extend to 25 hours – but only for new aircraft.

"I'm calling on the FAA to change the rulemaking," Homendy said, adding that she wanted to see aircraft retrofitted with 25-hour recorders, not just new planes.

"If that communication is not recorded, that is unfortunately a loss for us and a loss for the FAA and a loss for safety because that information is key not just for our investigation but for improving aviation safety," she said.

Congress should take action in the FAA reauthorization bill to ensure the proposed rule is adopted, Homendy said.

Debate about whether to adopt the longer recording standard weighs considerations about cost and privacy implications against safety.

The U.S. FAA has previously rejected the NTSB's call for mandating the retrofitting aircraft with new cockpit voice recorders, saying the costs would be significant at $741 million versus $196 million under incremental upgrades it proposed.

Pilots have also opposed the move, with the union representing pilots for air-freight company Atlas Air telling the FAA the longer recordings would be an invasion of worker privacy.

"(It) would significantly infringe upon the privacy rights of pilots and other flight crew members, as well as drastically increase the likelihood that CVR recordings will be misused or disseminated without authorization," the union said in a Dec. 28 response to the FAA's 25-hour proposal.

The issue has taken on new urgency after a series of near miss incidents raised alarms about U.S. air safety.

The NTSB has conducted 10 investigations since 2018 where the CVR was overwritten, including four runway incursions, Homendy said.

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