Why don't black boxes have their own GPS?

  • Why don't black boxes have their own GPS? Farhan

    In too many cases of unfortunate incidents, hunting for FDR (or CVR also) is a major challenge. There are many or all answers recorded on that device.

    Why cannot a locator (GPS linked) be included in the black box? It has its battery which runs for several days and very rigid outer shell.

    Ordinary cell phones are GPS enabled which pinpoint their location with the accuracy of less than 10 feet or so. Cannot there be more sophisticated technology built-in black boxes?

  • If you can receive a signal from the device, then you can already home in on where that signal is coming from. The signal does not need to include the position.

    GPS would also be of limited use. In most scenarios, it would probably be unable to receive a signal underneath water, terrain, weather, and wreckage. The GPS and antenna would also have to survive in order to function.

  • Actually, modern 406 Mhz ELT's do have GPS built-in and they transmit their location to satellites when activated.

    Since they are required by US regulations, it would be redundant to require the black box to have its own.

    From Wikipedia:

    GPS-based, registered
    The most modern 406 MHz beacons with GPS (US$ $300+ in 2010) track with a precision of 100 meters in the 70% of the world closest to the equator, and send a serial number so the responsible authority can look up phone numbers to notify the registrator (e.g. next-of-kin) in four minutes.

    The GPS system permits stationary, wide-view geosynchronous communications satellites to enhance the doppler position received by low Earth orbit satellites. EPIRB beacons with built-in GPS are usually called GPIRBs, for GPS Position-Indicating Radio Beacon or Global Position-Indicating Radio Beacon.

    However, rescue cannot begin until a doppler track is available. The COSPAS-SARSAT specifications say [7] that a beacon location is not considered "resolved" unless at least two doppler tracks match or a doppler track confirms an encoded (GPS) track. One or more GPS tracks are not sufficient.

  • First let's and define what "too many cases" means in terms of cold, hard, unfeeling numbers (as best we can):

    Wikipedia has a list (admittedly incomplete) of crashes where the CVR/FDR was not recovered. There are 16 crashes listed. I'll further add Air France 447 (which took "a long time" to find), and MH370 (which is currently unrecovered), bringing the total to 18.

    As Wikipedia admits their list is incomplete I'll double-and-round that in the name of being pessimistically conservative and say that since 1965 there have been 50 cases where it has taken "a long time" to recover the flight recorders (or they were never recovered).

    In a single year there can be over 100 "incidents". Even if we assume the CVR/FDR data wouldn't be useful for all of them there are still many hundreds (if not thousands) of incidents since 1965 where the cockpit voice recorder and/or flight data recorders have been recovered along with other wreckage or damaged airframes - often within a matter of days or hours (as soon as investigators can get to the wreckage). That's a pretty good track record.

    One could certainly argue (legitimately) that "one unrecovered flight recorder is too many", and indeed the goal is to always find the recorders and analyze their contents.
    If we're being realistic about this though we're going to have to accept the fact that sometimes you're just not going to recover the recorders: Aircraft crashes are messy, high-energy affairs and often involve inhospitable recovery environments like "the bottom of the ocean".

    If someone has better statistics close at hand I would love to review them and update this answer. Otherwise, it should be obvious that the above is an extremely rough off-the-cuff estimate, and should not be taken for any research or investigative purposes.
    In case it's not obvious - well I just said it.

    Now, to the meat of your question:

    Theoretically you could include a locator beacon in the CVR or FDR - incorporating a 406MHz ELT into the black box design is possible (you could even add a GPS to encode the device's location, though it would be of limited additional value with the inherent location accuracy of the 406MHz locator signal and satellite search system).

    So why don't we do it?

    As Lnafziger pointed out, airliners are already required to carry emergency locator transmitters - in any case where such a beacon would function including one in the CVR/FDR would be redundant with existing equipment in the aircraft.

    Further practical problems arise when you consider the kind of abuse a "black box" is subject to -- These things need to survive a crash (up to 3400 Gs), crush forces, fire, and immersion in water under pressure.
    Your typical distress beacon requires an antenna and a view of the sky, both of which would be in serious doubt after a crash: The black box may be inside or under wreckage, required external antennas may have been torn off or burned away, and distress beacon signals are unlikely to be received if the recorder is under water (this is why current generation recorders have sonar "pingers" to assist in locating them).

    To easily illustrate the sort of problem radio devices have with "stuff" between them and the sky, try this experiment: Take your cell phone, wrap it in aluminum foil to simulate the skin of a plane, put it in a zip-lock bag, and take it to the bottom of a pool. I bet you won't be able to get a call on that phone.

    Given the numerous failure modes (all of which are fairly high-probability in a real-world crash scenario), and the fact that we usually have a pretty good idea of where an aircraft is when a crash does happen, there isn't much to be gained by including additional locator technology in the CVR/FDR designs at this time - it just adds more components that would need periodic testing and recertification to ensure they are functioning properly and would activate appropriately in the event of a crash, while not appreciably improving our odds of finding the recorders.

  • To answer this question, you need to understand how GPS works. GPS satellites just keep continuously beaming the time the message was transmitter, and the position of the satellite at the time of the transmission.

    The GPS receiver/client then interprets your location based on the transit time of each message and computes the distance to each satellite.

    This means, the satellites or anyone other than your GPS receiver don't know your location. To transmit your location to anyone, you need a medium (such as the internet or GSM network), which is absent at the bottom of the ocean.

    Source: Wikipedia

  • Completely agree with Thilak. With a GPS receiver attached to a black box, only the black box will be able to know its own location. We are able to use GPS for tracking assets becuase those devices transmit the location information received from GPS, using various channels such as GPRS or satellite connectivity. In the case of black box - (a) GPS signals from satellites reaching the receiver is not guaranteed at all places e.g ocean beds. (b) If the black box did had the channel to transmit GPS information (Which it does not have) to back office, it could rather send much more actual data.

  • The answers are missing the point. Some companies have real time GPS enabled tracking on fleet trucks. You can go on a computer and check where these trucks have been 1 week back. When some of you say GPS signals can't penetrate deep waters, it would have at least sent it's last known coordinates before impact that could have been recorded if there was a system in place to record. Then we could better pinpoint impact areas.

Related questions and answers
  • Why is it that black boxes don't float? From what I gather the answer is: So they will not float away from a water crash site. The ping can be heard underwater with sonar. Finding the ping, finds the site. But why not have two black boxes one that floats and one that stays with the aircraft? That way if a plane is lost at sea, if we find the black box floating, we could use the data to find the other black box and the crash site. Plus the benefits of having a redundancy are enormous.

  • In too many cases of unfortunate incidents, hunting for FDR (or CVR also) is a major challenge. There are many or all answers recorded on that device. Why cannot a locator (GPS linked) be included in the black box? It has its battery which runs for several days and very rigid outer shell. Ordinary cell phones are GPS enabled which pinpoint their location with the accuracy of less than 10 feet or so. Cannot there be more sophisticated technology built-in black boxes?

  • I never knew much about airplanes before the tragic incident of Malaysia 370. I have been spending a lot of time on Twitter reading various articles and investigations; in one of the articles I read, they stated that unlike transponders, "black boxes" cannot be turned off. However, each ELT is specifically designed for each aircraft, so it cannot be tampered with. You also cannot turn off the black box, as it runs throughout the flight, recording every 30 to 60 seconds. Is it really impossible to turn off the black boxes from within the plane?

  • This is related to the recent disappearance and the fact that some claim the plane's black box to be deeply under water and that's why it cannot be located

  • Do the manufacturers who build airplanes use their own "black boxes" in the planes, or are there companies whose sole purpose is to develop black boxes? For example, in 2010 in the Airblue Flight 202 incident, the black box had to be sent to Germany for data recovery: He stated that the box would be examined by "foreign experts" in Germany or France as Pakistan does not possess... to the Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (BEA) in France. It is not clear who developed that black box. Was it the same company that manufactured the airplane? Also, can

  • that radio beacon. We have not yet picked up anything, but that's typically what those black boxes contain." I was under the (potentially incorrect) impression that flight recorders, by nature... Fleet, which is taking part in the search, said he expected the plane's flight recorders to be floating in the water. He said the recorders, also known as "black boxes", are fitted with radio...? If so, why? I know that flight recorders are equipped with underwater locator beacons. Are they also equipped with radio beacons (either an active transmitter or a some passive device like a corner

  • As I understand, there are two black boxes on-board an aircraft. One black box, the Cockpit Voice Recorder holds the cockpit conversations and the other, the Flight Data Recorder holds essential flight parameters. But why are the two black boxes holding separate data? Why don't both black boxes hold copies of both the FDR and the CVR data for extra redundancy in case the other box goes missing or is completely damaged by the crash? Are there any technical reasons for why this isn't possible or hasn't been attempted yet? Is there any benefit of having the CVR and FDR in separate boxes?

  • Black boxes put out a sonar ping at about 32kHz. From what I've read, depending on sea conditions the ping will be audible at the surface out to about 16 km, leaving a search area of around 1024 square km. By adding a little complexity to the ping circuit, you could encode within it the last received GPS position of the box, before it hits the water. With average sea depth and average sink angles of less than 45° that information would cut the search area down to about 10 square km. Is there some reason this tech is not used, or is it still in the rigorous testing pipeline these devices must

  • . This is just so we can find plane crashes in the sea when we don't know precisely where they went down (and to get basic data when the black boxes are too deep to get to immediately). Malaysian flight...Without getting into the mess of redesigning existing Flight Data Recorders, I have a simple proposal that I think would help in deep water crashes. I propose that several floating cushion sets... quite a bit of information including the final GPS coordinates before the crash. These devices would be light and cheap. I'd think current planes could be retrofitted very cheaply. The only challenge

  • I was looking through my virtual radar logs one of the days and found this "glitchy" ADS-B behavior. I am almost 100% sure that this is not due to my antenna or setup since two independent different radars confirmed this weird behavior from FlightRadar24. Also A/C before and after this one did not exhibit this behavior. Does anybody have any thoughts as to what may be happening??? Why... of occurrence is approximately: 3/16/2014 6:09pm CST I have also verified FlightAware is ALSO showing the same weird glitch. See below "yellow" highlighted airplane: Same A/C from FlightRadar24