Alaska 737 cockpit voice recorder data erasure renews industry safety debate
Alaska 737 cockpit voice recorder data erasure renews industry safety debate
By Valerie Insinna, David Shepardson and Lisa Barrington
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 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.
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because it was not retrieved within two hours - when recording restarts, erasing previous data.
OK, I agree it should be longer. We are no longer limited to magnetic tape spools. But once the aircraft is parked and shut down, why not stop the recording without having to pull a circuit breaker?
I'm just guessing, but if the plane suddenly decided it's parked and shut down while it's actually in the air ...
We might want that recording.It would take a metric buttload of things going wrong for that condition to happen. There are a lot of sensors tied to detecting that the aircraft is on the ground, and the system fails safe in air mode.
The CVR starts recording when the engines start running, and goes until both engines shut down with weight on wheels. It does not start recording when the aircraft has electrical power.
That’s just it. Did they run the engines on the ground for an hour so that it got overwritten?
That's what I'm wondering. The location the plane landed at may have gotten a maintenance check that night, but someone dropped the ball on downloading the FDR and CVR before doing so. Usually, when a plane is involved in an incident, it goes into quarantine until the FAA and NTSB have finished.