[001sky]

Point is a $100 spot device could be added (powered by Li AA's) as a backup system. This would have independent power supply and obviate the "need for cicuit breakers" being accessed. Or something like a lo-jack or whatever. Its completely embarassing to Boeing. Almost as bad as the pilot has a 64mb i phone and the [edit: voice recorders] holds only 2hrs? WTF. An Iphone might not itself survive, but the media allocations for the seem absyrdly low.

[dingaling]

> Point is a $100 spot device could be added (powered by Li AA's) as a backup system

Li AAs... without a means of isolating them from the circuitry?

How many aircraft are you prepared to lose through in-flight fires for this 'benefit'? Reference: Ethiopian Airlines 787 fire at Heathrow originating from lithium cells in the ELT.

Who is going to check the battery status at regular intervals?

Who is going to certify and sign-off those checks?

Who is going to be qualified to change those cells?

What interfaces will there be with the aircraft avionics to relay data such as call sign and flight code? How do we protect those connections from overload? There's a reason every single electrical circuit on an airliner can be isolated.

$100 is, frankly, a laughable estimate.

[001sky]

Laugh all you want, but the tech is pretty simple. You need to look at what it is doing. Replacing a transponder with something that is much simpler than an epirb. The example I gave is a $100 dollar current piece of tech that weigs 150 grams including power-source, and if it was available to LOS througha window could track the plane for 4-7 hours off a single set of batteries. If you want to raise the budget for an order of magnitude or two, for 10k dollars you could surely create a redundant system for the transponder.

The larger point is that any "real situation" that would need the transponder turned off (power/fire/corruption) would have almost no bearing on the operability of such a simple system.

FYI the imarsat pings are not all that different, are they? Its just a simple ping with some data that including headers is going to be very minimal payload...like SMS text type level of data.

[Aloha]

Yes, but the FDR is designed to survive multi-g impacts - how well would that smart phone survive?

[001sky]

The spot device doesn't need to survive a crash, just needs to send out a GPS ping once every 10 minutes. ie to give a fix on where the crash is would be sufficient.

[TylerE]

10 minutes isn't nearly enough. Remember you're talking about something moving at 8-10 miles per minute, 10 minutes, so worse case your solution will give a range about the size of Iowa.

[001sky]

You could increase the ping rate somewhat trivially. Look at what the trucking industry does to keep an eye on cargo. And in any event, the current 777 search area is how big?

[TylerE]

Solid state storage is pretty resilient.

[meepmorp]

Where do you get the 2 hour FDR capacity from? I've found references for 17-25 hours.

[001sky]

"And because the recorders keep only the last two hours of cockpit conversation..." (NY Times)

my mistake, meant the CVR [edited above to conform]

http://www.nytimes.com/2014/03/16/world/asia/series-of-error...