CVR/FDR battery life.

[Lightning6]

Bearing in mind the AF447 accident, would it not be possible to have back-up batteries, electronically controlled, to switch from the decaying battery to a freshly charged battery?

[NotPilotAtALL]

Hello,


This signal can be heard and located by a variety of receivers. The beacon will operate for 30-90 days (depending on the battery fitted) to a depth of 20,000 feet
So .. 30 days is not a limitation .. it's a choice made by the airline (I suppose)

Source:
Underwater locator beacon - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Underwater_locator_beacon)

See also:
Dukane Underwater Beacon (Pinger) - Science, Helderberg, and ZSSAS (http://www.scribd.com/doc/305198/Dukane-Underwater-Beacon-Pinger)

And:
NTSB - CVR & FDR (http://www.ntsb.gov/aviation/CVR_FDR.htm)
Note:
The NTSB do not mention that there are batteries that can run 90 days.
Is that 30 days is a minimum or a limit not to exceed imposed by the NTSB?

Regards.

[Lightning6]

Hello,

http://www.pprune.org/rumours-news/376433-af447-116.html#post5019589



Regards.

Yes, I read the posts on this on the R&N thread, thought it more appropriate over here...The point I was making was, should they be upgraded with back-up batteries to give them a longer output.

[makrider]

Put another backup battery into an equipment does not ensure that is retrieved from the bottom of the ocean at 20.000 ft.

The first step is to find the signal, but the very hard work is retrive the equipment form the water.

From my point of wiew, 30 Days appears to be a reasonable time with the actual technology. :ok:

Mak

[NotPilotAtALL]

Hello,

The first step is to find the signal, but the very hard work is retrive the equipment form the water.Sorry for disagree but on the contrary .. the very hard job is to locate the black boxes and the easy (more easy) job is to retrive the boxes from underwater....
So more long life of battery ... more better chance to locate boxes!
BTW .. still 5 days before the batteries are drained .. and the boxes are not yet located....
When this will be no more emissions .. it will be very very hard to find them ..

Regards.

[makrider]

Not very really...

In fact at 20000 feet you have the signal in huge area...
The hard work is to locate the exact position...and after that you need to descent at 4000 mt and retrive it...Not very easy...

I agree that in this case probably a longer life of the battery give a better chance to locate the FDR but 30 days remain a very long time and in the case of AF447 need to consider that the survey start after about 7 days, and furthermore we don't have a crash point...

I hope however that it can be found in the next few hours ...

Mak

[BryceM]

You can extend the battery life very easily by reducing the ping rate most of the battery power is expended in putting acoustic energy into the water.

Halving the ping rate would do something close to doubling the battery life (assuming the design of the device is competent, which I assume it is).

If the number of search vessels is large enough, the reduced frequency wouldn't reduce the chances of the beacon being found. (Each vessel has to travel more slowly to have the same chance of hearing a pinger which uses a lower ping rate, so each vessel searches a smaller area - so you need (roughly) twice the number of vessels if the ping rate is halved).

I'd be in favour of not activating the pinger for the first 96 hours to allow detection vessels to start to be deployed in the area, followed by a couple of weeks of operation at the current ping rate, then a further month at a reduced rate (by this time, you know you're not going to find the recorders easily, and have had time to assemble a decent search fleet).