Ask HN: Why do airlines still use "black boxes" ?
Why not substitute a real-time satellite uplink? This would eliminate the need for expensive and often unsuccessful oceanic search expeditions of the kind we are now hearing about.
Addition: the NTSB is expert at retrieving data from severely damaged black boxes.
There's also a practicality argument: when a plane is flying along normally, you don't need consistent satellite information - you've got radio communication, radio data-links, and controllers watching. So the usefulness of a satellite uplink only comes when something is not right with the plane.
If we're in that situation - that there's something wrong enough with the plane that you'd want to know about it via the uplink - what makes you think the uplink will still be working? Air planes are designed with huge levels of redundancy and overengineered margins: are you going to take all that, double it, and then put it into a satellite transmitter (which probably won't have that much data to send anyways if the plane is in that state)?
So no, I don't think we need constant satellite uplinks. Black boxes (especially ones of the newer generation) are very well-engineered, and the NTSB guys are masters at getting things off broken ones.
Redundancy is good, always. Especially when the cost is negligible compared to the lifetime operating expense of the machine and the costs from any misinformation regarding the last moments of a doomed flight (a Crash that is the Airline's fault mega-screws them in the wallet).
Having said that, your question does resonate well with me too. How much data does a black box store that we can't send it over satellite (or even to other aircraft nearby-- think of a distributed storage) in real-time or near real-time? The purpose of such distribution is purely redundancy. I haven't seen any concrete numbers or engineering barriers against this idea, yet.
Guess where the hackers are going to concentrate their efforts. And given the large number of access points required to make that all happen, guess how often the database will be compromised.
Some comments I've in other discussions brought up plane-to-plane communications, but other craft aren't commonly close enough to have any relevant weather information to share. (I'd extrapolate to think you'd have similar issues reliably transmitting data.)
Some fascinating comments below this post by the way: http://www.weathergraphics.com/tim/af447/
With 16-bit precision, you can get 528 sensor updates for the same amount of bandwidth. Let's cut that in half (~250 sensors) and reduce the frequency to 30 Hz, then we've gone from 825 kbps to 274.5 kbps. Multiply by 8000 planes, that's 1.8 Gbps aggregate. With stream compression, a lot less.
Challenging? Sure. But I think even my restatement is too much data. Maybe send data less often if everything is within "normal operating parameters." I bet most sensors don't need 16 bits of precision, or to be updated even once per second. Cut my estimate to 10%, that's <30 kbps per plane, <200 Mbps total. Easy!
People really ought to try to grasp how quickly things can go wrong in the real world, and how difficult it can be to tell what made the nice shiny silver bird look like the crumpled foil discard of a cigarette pack smeared with a poorly-preserved meat jelly. You only have to see one used-to-be jet (complete with used-to-be pilot) before you start wondering how anyone could make sense of it -- and that's with the physical evidence in hand.
I don't know much about aircraft controlling software, so this is only a guess from my experience of general system software crash recovery; usually the hardest case is caused by something I've never imagined to happen.
Probably the only viable alternative that is still reliable would be single sideband (SSB), but that would be a infrastructure change as well.
If you consider what is required to do a digital encoding including handshaking, synchronization and the like, you are less likely to have a less reliable system. If in the midst of an AM transmission you get a static crash, it likely deletes one word. In a digital system, you might well have to resync, like a modem.
So some of these systems need to be very reliable under all sorts of harsh conditions. The questions I would ask, is 1) do the satellites already exist 2) how many of them and 3) are they visible everywhere there are airflights? and finally 4) how expensive is this network to maintain?
My guess is that the cost of such a network is a lot greater than a few black-box searches. Additionally, for really difficult crashes, they retrieve every possible piece of the airplane, at an expense that makes finding the black box seem small: http://en.wikipedia.org/wiki/TWA_Flight_800
The idea of a distributed network among commercial aircraft and ground stations as a method of transmitting the data also seems like an exciting prospect, and perhaps less expensive than relying on satellite communications, though I know nothing of the range or viability of such a platform.
In any case, a system to complement a black box would require large expenditures by governments and airlines. But, how valuable is that data? Pretty valuable, I think.
http://en.wikipedia.org/wiki/Emergency_Position-Indicating_R...
The ELT is to locate the debris field. (OK, it is officially to locate the survivors, but they tend to be in the debris field.) If the crash is on land, another radio to locate the black box is unnecessary. If it is in the water, a radio transmitter is useless, but a pinger is very useful (see other debate threads why floating black boxes aren't a good idea, and impractical to boot - the armor is very heavy).
Sending a signal makes it easier to find - that's not stupid whether or not it sinks.
Sinking means that it doesn't move much. However, since it's attached to the plane, it's likely to go down with the airplane whether or it it would sink on its own, whether or not it sinks on its own is irrelevant.
The aircraft itself will also carry an underwater acoustic beacon (pinging at about 40KHz) or two so that underwater wreckage can be located once the general area has been established by the ELT that should have been jettisoned on impact. Both items (the ELT and the UAB) have limited battery life -- they pump out huge signals relative to their size. By convention, the UAB is located in the same general area as the FDR and CVR longitudinally.
In the case of the Air France flight incident, it would seem that the ELT did not work or was at a significant distance from the crash site by the time the search reached the position. That the black boxes (the FDR and CVR) are expected to be recoverable at this point seems to indicate that the UAB did work (it would have been detected by a sonobuoy dropped by the search airplane, which looked to me like it was equipped with anti-submarine warfare equipment, judging by the MAD boom on the tail).
Some modern recorders on board aircraft can apparently do similar tricks, but I'd imagine it's more difficult to make it work reliably; the stresses involved in a plane crash are likely far greater, and I'd suspect the number of places from which a device could both survive and get free to deploy is much smaller.
Keep the present system and add a second automatically jettisoned flash memory copy of all data that is designed to float if at sea. It would also transmit a signal that would include its GPS location if possible.
Jettisoning could be set to occur at a given altitude, a given set of data values or a given acceleration/deceleration values.
Air travel phobia seems to be rooted in the lack of control experienced by the passenger - specifically, in the anticipation of utter helplessness in the event of a crash. A parachute would help with that, even if its role is largely ceremonial.
I'd prefer to fly on planes which aren't execution chambers for criminal and witness alike. The market refuses to provide me with this option, however.
Because that would have significant side effects. Since parachutes are pretty much useless on airliners anyway, no significant side effects from banning them.
lol, it's pre coffee reading that will do me in everytime.
What are you talking about? The market already provides that option in several forms:
1. Learn to fly and fly yourself. 2. Rent a pilot and a plane and get to where you want to be.
You might not be able to afford those options, but they are there.
The reality is, that you are in fact utterly helpless in the event of a crash.
You can't use them when too high up (not enough O2) or too low (not enough time to deploy). Most crashes take place on takeoff or landing.
Of the problems that do happen that would take you through a "jumpable" altitude, you can only make the jump if you 1) have time, 2) have enough airplane left to jump out of. If a big whole ripped in the plane while in flight at 30k feet, you are very likely already unconscious or dead.
There are other issues related to the fact that commercial airliners are not made to be jumped out of at speed. Its difficult or impossible to open their doors during flight (with good reason). Even if you could get them open, there may not be a jump trajectory from some doors that doesn't provide a personal introduction to wing or engine part. Also, you cannot jump and live from a plane going 300 knots. The plane would have to decelerate to near stall to make it safe and if its already crashing, maneuvering at the edge of performance is not likely.
Also, consider that professional and military jumpers are highly trained, in top physical shape, and the landing sites are carefully chosen to avoid injury. As a fun thought experiment, take Rosanne Bar, put her in a small canopy "emergency chute", and drop her, at random, over the Arizona desert. (She was on her way to Vegas, baby). Calculate survivability.
Chutes for everyone would be expensive, heavy and probably only be beneficial in single digit percentages (or even sub single) of all crashes. They would very likely cause more problems than they would solve.
Notably, reviews have been mixed. http://en.wikipedia.org/wiki/Ballistic_Recovery_Systems
Cirrus, it should be noted has an below average crash rate compared to other aircraft in class. Clearly, the small total of 18 deployments compared to the crash rate leaves a lot of work to be done.
Airplane doors CANNOT be opened in flight unless you depressurize the airplane first. Even then, it would probably be difficult. The only airliner (that I am aware of) that could have the rear stairs opened in flight was the 727, which was "fixed" after D.B. Cooper took that way out. (Odds are pretty good he didn't make it, either.)
1. Operational knowledge is lacking.
2. 300 people trying to jump from a plane through 2 3 foot doors will probably cause a crash alone.
3. Pointless at > FL 10. There is no oxygen up there.
4. It's also about -50C ish > FL 10. You would fall as a frozen popsicle.
5. Would add about 1000lbs of weight to the aircraft.
6. People floating around in the Atlantic isn't really an improvement.
7. 95% of all aircraft failures result in a safe landing. Only a small percentage result in crashes at the commercial aircraft level.
8. People hanging in trees all over the province of Alberta isn't really an improvement.
9. People landing in traffic in Denver isn't really an improvement.
I think you get the point. The answer is that parachutes are completely impractical for 90% of all aviation uses.
HALO jumpers breathe pure oxygen onboard and jump with oxygen tanks. A single breathe during the transfer is enough to return your nitrogen levels to normal and cause blackout on egress. Any kind of medical condition, even anxiety or exhaustion can dramatically affect your susceptibility to hypoxia and normal clothes would not save you from frostbite.
By the way, 747's cruise at up to 40k altitude and 565mph. Jumping out is not a good idea.
It is the sudden stop at the end.