43

You can't, because it is in fact forbidden to release CVR audio under US law. From the NTSB: The CVR recordings are treated differently than the other factual information obtained in an accident investigation. Due to the highly sensitive nature of the verbal communications inside the cockpit, Congress has required that the Safety Board not release any ...


40

This is actually a fairly standard thing to do with electronics that have been submerged: They are placed in water (ideally fresh, clean water) to both delay the onset of corrosion and dilute any salts or other chemicals that they came in contact with while submerged. When you remove electronics from water and let them dry out they begin to form corrosion ...


38

There are two recorders that are mandatory on board commercial aircraft: CVR for voice, and FDR for data. They are designed to survive an accident and include an ultrasonic beacon to facilitate locating them underwater. (Source) It's worth mentioning that CVR and FDR are not connected to any external data port for data export/copy/extraction, and ...


26

One of the channels of the Cockpit Voice Recorder is the microphone on each pilot's headset. This is much closer to the source of the breathing noise than your own ears. The microphone may also not have a wind filter so breathing on it will generate a lot of noise.


23

The CVR (and FDR) are continuously recording while the aircraft is in operation. In the days of magnetic tape, this was done with a continuous loop. In digital systems, the same is emulated by automatically returning to the start of the storage area whenever the end is reached. In both cases, the new data always overwrites the oldest data, so the last N ...


22

There's seldom a reason for manufacturers to design and build their own black boxes. It's expensive to run a production line to design, build a test a few. It's just cheaper to get an agreement with a company to make them for you. The second photo below shows a popular recurring model from Honeywell, which appears to have been used on the A330, B737 and B777....


22

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 ...


22

The image of the recovered "black box" is showing the Cockpit Voice Recorder (CVR). The data is stored in the cylindrical housing that was relatively undamaged in the crash. The housing consists of a stainless steel outer shell to withstand impact forces. Beneath it is a layers of high temperature insulation to protect the data storage from post crash fire....


20

You probably wouldn't believe the effort needed to certify anything that flies on an aircraft. This is a multi-year process, especially if it is so much security-related as the CVR and FDR. And it needs to be done with all national authorities of your intended customers. This is a case of good-enough. The advantage from combining both is real, but so small, ...


20

Addressing just your first item, the purpose of the cockpit voice recorder is to provide a record of all sounds in the cockpit from the time the recording stops back to however long the recording loop goes for. It should be used for accident or incident investigation only. You don't want pilots modifying what they say (or passing notes or using hand signals) ...


17

The Wikipedia article on Flight recorder offers a possible explanation for the origin of the term: ... they were essentially photograph-based flight recorders since the record was made on a scrolling photographic film. The latent image was made by a thin ray of light deviated by a mirror tilted according to the magnitude of the data to record (altitude, ...


17

The CVR and FDR have impact switches to stop recording when they experience high acceleration. In incidents and accidents that don't involve high enough acceleration, the plane remains intact enough for the boxes to be immediately found and switched off manually. In more serious crashes, the boxes stop recording because of the physical destruction of ...


15

A black box (generally speaking) is a device or box whose internal working are not of as much interest or value but rather the input and output. Flight data recorders are orange so that they can be located easily in case of a crash. If they were black, they can be camouflaged by their surroundings. Bright orange color make them stand out easily, because ...


14

This excellent explanation is taken from Avionics News in 2006: FDRs are equipped with an Underwater Locator Beacon (ULB). If you look at a picture of an FDR, you will almost always see a small, cylindrical object attached to one end of the device. If a plane crashes into the water, this beacon sends out an ultrasonic pulse that cannot be heard by human ...


14

The headsets worn by the pilots have a microphone arm. These audio channels are split and routed to the black box. Additionally, there is at least one microphone embedded in the cockpit, usually overhead. The black box can support recording of up to 4 audio channels, so each channel can be examined separately. Since the headsets and overhead microphone ...


13

Pilot's breath is not recorded on a flight data recorder, as it is not one of the data parameters. However, if a pilot is breathing abnormally, the cockpit voice recorder may easily detect that as the breathing sound is captured by the CVR. A reference to this can be found in the press conference summary for Germanwings flight 4U9525, which states: ... ...


12

If the fuse was pulled between the previous flight and the crash then yes, the CVR can only record when it has power Pulling the fuse or going behind the panel and cutting the wire will prevent it from recording.


12

No. Federal law prohibits the NTSB from releasing any CVR recordings, and the NTSB notes that they are exempt from FOIA requests. The same law requires them to release a transcript, like the ones seen in accident reports, if the transcript is relevant to the accident or incident. See 49 U.S.C. § 1114(c): (1) The Board may not disclose publicly any part ...


12

Aviation manufacturers generally design the equipment to comply with legal requirements. Under FAA two hours is what is required by law. 14 CFR 121.359–Operating Requirements: Domestic, Flag, and Supplemental Operations–Cockpit Voice Recorders (i) By April 7, 2012, all turbine engine-powered airplanes subject to this section that are ...


11

CVRs are normally active as soon as one of the basic electrical buses, like the battery bus, or emergency bus, is energized. So if the airplane has a BATTERY MASTER switch or similar, it is recording audio as you as you switch it on, so pretty much as soon as you climb in and start getting things ready. CVRs will include a G switch to stop recording in a ...


10

The correct answer seems to be, "Nobody knows for sure" but here's some data. The earliest citation in the Oxford English Dictionary for the phrase "black box" referring specifically to a flight data recorder isn't until 1964, from the UK Daily Telegraph: "The flight recorder is an indestructible 'black box' which automatically records the key functions in ...


10

As ratchetfreak noted, the recorders don't transmit data, attached to them is a location beacon that operates for up to 30 days. This location beacon isn't always successful in enabling searchers to find the recorders. In the case of AF447, it took two years before a search located the aircraft debris field on the sea floor and recovered it's recorders. As ...


10

You can't listen to it due to the regulation mentioned in Sanchises' answer, but you can find the transcripts. There is one here, for example.


9

FDR and CVR don't transmit anything they just record data onto a magnetic tape or in a solid state drive, when the plane crashes/explodes they become just part of the debris and wait until they get found. The boxes are rated to survive nearly any feasible aircraft crash. The special case is if they get submerged, then the attached locator beacon will ...


9

You are very correct that this can happen- If i'm not wrong, what happened during the last 6 minutes of Swissair Flight 111 will never be known for this reason. In general however, by the time the fire would spread to this extent the CVR and/or FDR would probably have picked up some hint of fire and the reason. To increase survivability, the FDR and CVR ...


9

Many new aircraft, starting with the Boeing 787, are equipped with enhanced airborne flight recorders (EAFR). EAFRs are designed to the ARINC 767 architecture (described here). They combine the functions of the legacy FDRs and CVRs. The EAFR is designed to be compatible with aircraft using the ARINC 664 network for their avionics. As a result they are ...


9

It depends a bit. One of the microphones for the cockpit voice recorder is an "area microphone," which is designed to record whatever someone standing in the cockpit would hear (the others record from crew headsets and possibly the PA system). This area mic is continuously recording; it does not just turn on when there's more than some threshold of noise. If ...


9

In the United States, CVRs and FDRs have a 10 minute (+/- 1 minute) battery requirement to allow any available post-crash voice and data to be recorded, with power removed once a timer limit is reached. While I'm not familiar with the internals of the FDR, simple circuitry could trigger the timer to start based on current flow from the battery, if not for ...


8

Each of the three crew gets its own array of mics including the hand mic, boom mic, mask mic, his speaker and headphones (the microphone he uses for radio communication and what he hears from the radio). The third crew member's channel may be connected to the PA. The fourth required channel is for the cockpit area mic which records general sounds and alerts....


8

After being sunk in water, especially salt water, the devices are more susceptible to corrosion when removed from the water. In order to better ensure a successful recovery of the data contained within, the investigators keep them immersed in water until they can be properly cleaned and dried in a laboratory. If they were to be simply removed into the air, ...


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