> It seems very clear that these airplane blackboxes are ridiculously under-specced and underpowered.
Sorry but you really don't know what you are talking about. Black boxes are not made to be latest generation hardware and top class storage equipments, they are made to resist and survive and air crash as their first priority. And in most cases (i.e. crash on land, since most crashes occur at take-off or landing) 30 days is far enough to recover the data and the black box.
Note that even without the beacon, the AF Rio flight black boxes were recovered 2 years after the crash, under extreme depths of water.
> Black boxes are not made to be latest generation hardware and top class storage equipments, they are made to resist and survive and air crash as their first priority.
You could say the same about, say, the body of the airplane or the engines. But we have innovation in those fields (composite materials, exotic metals, etc.).
The point is: 2 hours is simply not enough. The BB should be able to hold the entire flight's data; and our current technology (in terms of processing power and storage capacity) is more than enough to do that. Plus, given that the BB is a modular, independent unit it would be easy to swap out an older BB with a newer, better BB.
Why 2 hours isn't enough? We're talking about voice conversation between the crew. Mot of the information meaningful to investigation would happen in a short period of time prior to the crash.
Usually correct I imagine but what about the slow de-pressurisation scenarios where the pilots have passed out and the plane flies until it runs out of fuel?
In this case (whatever the cause) it would definitely be useful to have the recording for the time the plane went off the planned route but that will probably have been overwritten.
That's a good point. However I believe low pressurization event is captured by the data recorder. That information, coupled with other events, and the fact that the voice recorder goes silent for 2 hours, would give investigators sufficient clue.
I don't have any inside knowledge of how blackbox works the way it does, but I imagine, like with any critical system, reliability and redundancy trump everything else. I bet the two hour limit is not an arbitrary number but rather result of some lengthy tried and true testing process and debate. Any design decision is a trade-off, no matter how small.
I'd argue that, if we have learned anything from MH370, ensuring blackbox survive in the harshest environments in the planet and stay discoverable for long period of time should be the utmost concerns.
Why can't the damn thing record audio (and lots of other data) from the entire flight, rather than only two hours?
I commented on this on a prior thread [1]. There has been push back from the Airline Pilots Association against longer recording duration on privacy grounds:
The Air Line Pilots Association (ALPA) did not support the proposal to increase CVR recording time because the FAA did not propose any increase in the privacy protections regarding the access and use of information recorded on a CVR. The ALPA stated that existing protections are inadequate despite years of its attempts to change the standard.
>>Why not have an atomic (nuclear) battery that will be able to send out sonic pings for a year?
Because atomic batteries use RTG cells which convert heat directly into electricity - and that's one of the most inefficient ways of doing it, which means, that for amounts which would be safe to put in an airplane, you would have maybe a couple watts of power, and I doubt you would even get that much. Also, nuclear batteries don't last forever, for them to be producing power a highly radioactive materials must be used,with super-short half lives - a material with a half life of hundreds of years doesn't produce enough heat through radioactive decay.
Which means that those batteries would have to be frequently replaced - and as with anything nuclear, the costs would be enormous. 30 days to find the black box after a crash is plenty.
Atomic batteries are not at all powerful enough. Microwatts.
Running anything on batteries for days takes a lot of batteries. A Raspberry Pi for 2 days for example takes somewhere from 1.5 to 2 kg of li-ion batteries.
That sort of weight starts to be really problematic for a device which needs to survive a plane crash - since every bit of extra mass increases the force with which it hits.
They don't have to be microwatts. Galileo, for example, used 17 pounds of plutonium to generate 570W of power at launch, with a half life of about 88 years.
Not that you'd want to carry 17 pounds of plutonium around on an airliner all the time, but power output is not an insurmountable problem by itself.
Sticking a bunch of nuclear material on airliners to aid in accident investigation seems kind of counterproductive. Imagine how much more fun the 9/11 cleanup at the Pentagon and WTC would have been if the workers got to play "find the needle in the haystack" with a couple of pounds of plutonium along with all the rest.
I don't understand why the pingers are on continuously until battery depletion. Assuming we can't have them be triggered by incoming sound (making them essentially sonar transponders), why couldn't they be on for e.g. 15 days, then off for a month, on for 7 days, off for two more months and on for 7 days? The power requirements of the timing device are minuscule (my watch needs a new battery every few years).
How would turning the pinger off for a month help? It just means that the search operation stops for a whole month while they wait for the pings to resume. I don't understand how your proposed idea would benefit a rescue operation.
I'd suggest something more sensible. E.g. one ping every Ns for the first 15 days, every 2Ns for the next 15 days, every 4Ns for the next 15 days... oh look, "infinite" duration.
However, I suspect the "pinger" mechanism is very, very simple and completely analog. No logic in its circuit at all. Because having it SURVIVE to ping 30d was the key consideration.
