Originally Posted by snowfalcon2
I don't really understand this fuss about independent power supply.
Here is what the report mentioned :
Although the loss of flight recorder information for the last 19 minutes of the engines-out descent and landing on this occurrence did not adversely affect the investigation to this occurrence, had the circumstances been different,
the lack of data following the power loss on both engines could have severely affected the ability of the investigation to make findings as to the causes and contributing factors to this occurrence.
Originally Posted by PJ2
The only suggestion of independent power supply that has emerged was after SR111 and that was the voice recorder.
It is not the only one, the Portuguese had also made an explicit recommendation :
SAFETY RECOMMENDATION AJ/2004
Therefore, it is recommended that the European Organization for Civil Aviation Equipment, ICAO, all civil aviation authorities and safety investigation authorities:
• Take into account the circumstances of this particular occurrence in their deliberations on the requirements for independent power supplies for on-board aircraft recordings.
As a matter of fact, I can now read from the FCOM :
The recording system is automatically active in flight (whether the engines are running or not).
Although this does not seem to apply to the CVR which will powered only if the emergency generator is supplied by the engine hydraulic pumps ...