"The analysis revealed that both the CVR and FDR data were not recording during the four minutes leading up to the aircraft's collision"
How does this even happen where two systems would stop recording data. This story seems to get weirder and weirder. I'd always been under the impression that black boxes were really highly secure and extremely rigorously developed to specifically prevent data loss in situations like this.
Bad enough for the accident to occur, but to not have accurate telemetry and recorded data from the onboard systems is definitely going to make an already hard investigation very much harder
According to 737NG technical diagrams I found online, the CVR is powered by the XFER BUS 2, and the FDR by the DC BUS 1. Neither of these busses can operate from the battery, but both should be operating if either engine or the APU is running, provided all switches are in the correct position. On the surface it seems odd to not run the CVR/FDR from battery, but on the other hand it’s not a critical flight system.
This suggests either dual engine failure, or single engine failure followed by shutting down the wrong engine with the fire handle (which cuts off electrical power), or (unlikely) a catastrophic electrical system failure. This isn’t a new interpretation, since the ADSB transponder also shut down at about the same time which led many to assume the electrics had gone out for some reason. My guess remains that they shut down the wrong engine given that the reported bird strike occurred (reportedly) a few minutes before the plane seems to have lost power, but the timeline is still not certain.
However, it did seem like the engine that had the mobile footage with the compressor stalls was still running at landing which should usually be enough to generate electricity since even windmilling is enough, which adds another wrinkle. Perhaps the bird strike destroyed the generator?
Some recorders have a built in battery for exactly these cases (called Recorder Independent Power Supply), and (as I discovered while trying to figure out whether this exists) Canada seems to require them since 2023.
It might still give us some hints. In the other thread they say that the black box might have stopped recording because of a power failure - and planes manufactured before 2010 (this plane was from 2009) didn't need an UPS.
The hint that we get from this news is that the plane (or better, the blackbox) was missing electricity for 4 minutes prior to the crash.
How does this even happen where two systems would stop recording data. This story seems to get weirder and weirder. I'd always been under the impression that black boxes were really highly secure and extremely rigorously developed to specifically prevent data loss in situations like this.
Bad enough for the accident to occur, but to not have accurate telemetry and recorded data from the onboard systems is definitely going to make an already hard investigation very much harder