4 ms·

I believe the Cockpit Voice Recorder (CVR) only keeps two hours, but the Flight Data Recorder (FDR) records for considerably longer. Both make up a black box.

I believe the Cockpit Voice Recorder (CVR) only keeps two hours, but the Flight Data Recorder (FDR) records for considerably longer. Both make up a black box. It will certainly be far more difficult to establish what happened without voice recordings though.

Eliezer 13y ago
I guess they try to keep the airplanes cheap enough that they can't spring for a 16gb card in the CVR.
- marshray 13y ago
  If you think the rule about turning off your electronics during takeoff and landing is conservative, try to imagine what it would take to certify a solid-state memory card for use in that application.
  - 001sky 13y ago
    Why would doubling or quadrupuling the storage be a problem? Assuming you have the cost of a new chip paid for, I dont see the capacity issue. Or are you saying solid state is incompatible with the engineering parameters of a black box altogether? In that case, the answer is even simpler: just add more of what's already in there.
    - mpyne 13y ago
      That's the point, it's not simply a capacity issue. They could plug in a $10 SD card that comes pre-installed to a Nintendo DS and solve the capacity issue. Rather, it's a certification issue, and the certification process itself is so expensive that you don't simply upgrade every black box every 4 years as storage gets cheaper.
      - ams6110 13y ago
        There's also a pilots union issue, they don't want every offhand utterance, gripes about management, gossip, etc. preserved for eternity.
        001sky 13y ago
        This sounds more likely the real answer.
        ddeck 13y ago
        This is correct. Looking at the most recent FAA CVR reg. revision in 2008, which increased the required duration to 2 hours: "Revisions to Cockpit Voice Recorder and Digital Flight Data Recorder Regulations" [1] The FAA proposed that all CVRs be able to retain the last two hours of cockpit audio. Both the NTSB and the Transportation Safety Board of Canada noted that the short duration of available cockpit audio hindered the investigation of several accidents. 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. [1] http://www.gpo.gov/fdsys/pkg/FR-2008-03-07/pdf/E8-3949.pdf http://www.gpo.gov/fdsys/pkg/FR-2008-03-07/pdf/E8-3949.pdf
        Eliezer 13y ago
        That actually sounds fairly legit, especially since the commenter below notes that the union has asked for more privacy protections but not received them. Hadn't realized the policy debate was multi-sided.
      - 001sky 13y ago
        Just to be clear, I mean an actual aero-space chip specifically made for this application. Here is a cost estimate. Its $8K/per, but honestly that's a just a single pair of first class tickets... The U.S. National Transportation Safety Board has asked for the installation of cockpit image recorders in large transport aircraft to provide information that would supplement existing CVR and FDR data in accident investigations. They also recommended image recorders be placed into smaller aircraft that are not required to have a CVR or FDR.[4] Such systems, estimated to cost less than $8,000 installed, typically consist of a camera and microphone located in the cockpit to continuously record cockpit instrumentation, the outside viewing area, engine sounds, radio communications, and ambient cockpit sounds. As with conventional CVRs and FDRs, data from such a system is stored in a crash-protected unit to ensure survivability.[4]
    - deleted 13y ago
      [deleted]
    - InclinedPlane 13y ago
      Which is worse? A plane goes down and you have too little data because of strict regulations or a plane goes down and you have no data because of loose regulations?
- ekianjo 13y ago
  yeah i'm sure you 16gb SD card data is made to survive several hundred Gs collision crash. EDIT : adjusted Gs
  - anigbrowl 13y ago
    It doesn't matter that much whether it does or not. Modern data storage is so cheap that we could stick in 8 of them in addition to the super-touch CVR at very little extra cost, and odds are that one of the cheapie units would survive. The hardened CVR system is great, but it should be a last resort sort of thing. We can have cheap, redundant, and high-capacity systems in addition to the CVR for peanuts, so why don't we?
  - Symmetry 13y ago
    Actually a small device with no internal moving parts will take 50Gs no problem, 1000s of Gs if you have some decent potting. It's keeping some sort of power source active through a high G crash that's the challenge.
  - chaz 13y ago
    SwissAir 111 impacted at an estimated 350g.
    - vacri 13y ago
      The sudden stop at the end of a fall is routinely that high. If you look at warranties for spinning disc hard drives, they'll be rated for several hundred G during transit. Sounds silly, but it's the difference between landing on a surface with give, like carpet, or landing on an unforgiving surface like concrete.

Eliezer 13y ago

I guess they try to keep the airplanes cheap enough that they can't spring for a 16gb card in the CVR.

marshray 13y ago
If you think the rule about turning off your electronics during takeoff and landing is conservative, try to imagine what it would take to certify a solid-state memory card for use in that application.
- 001sky 13y ago
  Why would doubling or quadrupuling the storage be a problem? Assuming you have the cost of a new chip paid for, I dont see the capacity issue. Or are you saying solid state is incompatible with the engineering parameters of a black box altogether? In that case, the answer is even simpler: just add more of what's already in there.
  - mpyne 13y ago
    That's the point, it's not simply a capacity issue. They could plug in a $10 SD card that comes pre-installed to a Nintendo DS and solve the capacity issue. Rather, it's a certification issue, and the certification process itself is so expensive that you don't simply upgrade every black box every 4 years as storage gets cheaper.
    - ams6110 13y ago
      There's also a pilots union issue, they don't want every offhand utterance, gripes about management, gossip, etc. preserved for eternity.
      - 001sky 13y ago
        This sounds more likely the real answer.
      - ddeck 13y ago
        This is correct. Looking at the most recent FAA CVR reg. revision in 2008, which increased the required duration to 2 hours: "Revisions to Cockpit Voice Recorder and Digital Flight Data Recorder Regulations" [1] The FAA proposed that all CVRs be able to retain the last two hours of cockpit audio. Both the NTSB and the Transportation Safety Board of Canada noted that the short duration of available cockpit audio hindered the investigation of several accidents. 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. [1] http://www.gpo.gov/fdsys/pkg/FR-2008-03-07/pdf/E8-3949.pdf http://www.gpo.gov/fdsys/pkg/FR-2008-03-07/pdf/E8-3949.pdf
      - Eliezer 13y ago
        That actually sounds fairly legit, especially since the commenter below notes that the union has asked for more privacy protections but not received them. Hadn't realized the policy debate was multi-sided.
    - 001sky 13y ago
      Just to be clear, I mean an actual aero-space chip specifically made for this application. Here is a cost estimate. Its $8K/per, but honestly that's a just a single pair of first class tickets... The U.S. National Transportation Safety Board has asked for the installation of cockpit image recorders in large transport aircraft to provide information that would supplement existing CVR and FDR data in accident investigations. They also recommended image recorders be placed into smaller aircraft that are not required to have a CVR or FDR.[4] Such systems, estimated to cost less than $8,000 installed, typically consist of a camera and microphone located in the cockpit to continuously record cockpit instrumentation, the outside viewing area, engine sounds, radio communications, and ambient cockpit sounds. As with conventional CVRs and FDRs, data from such a system is stored in a crash-protected unit to ensure survivability.[4]
  - deleted 13y ago
    [deleted]
  - InclinedPlane 13y ago
    Which is worse? A plane goes down and you have too little data because of strict regulations or a plane goes down and you have no data because of loose regulations?
ekianjo 13y ago
yeah i'm sure you 16gb SD card data is made to survive several hundred Gs collision crash. EDIT : adjusted Gs
- anigbrowl 13y ago
  It doesn't matter that much whether it does or not. Modern data storage is so cheap that we could stick in 8 of them in addition to the super-touch CVR at very little extra cost, and odds are that one of the cheapie units would survive. The hardened CVR system is great, but it should be a last resort sort of thing. We can have cheap, redundant, and high-capacity systems in addition to the CVR for peanuts, so why don't we?
- Symmetry 13y ago
  Actually a small device with no internal moving parts will take 50Gs no problem, 1000s of Gs if you have some decent potting. It's keeping some sort of power source active through a high G crash that's the challenge.
- chaz 13y ago
  SwissAir 111 impacted at an estimated 350g.
  - vacri 13y ago
    The sudden stop at the end of a fall is routinely that high. If you look at warranties for spinning disc hard drives, they'll be rated for several hundred G during transit. Sounds silly, but it's the difference between landing on a surface with give, like carpet, or landing on an unforgiving surface like concrete.