Black Box

About Black Boxes

In aviation, black boxes refer to the aircraft’s Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR). Both collect and store data from a variety of airplane sensors in a memory unit that is designed to survive a crash. The FDR records selected flight parameters, both mandatory and non mandatory continuously for 25 hours. The CVR captures all sounds in the cockpit such as conversations, engine noise, landing gear noise, warning sounds and radio transmission continuously for 30 minutes.

CVRs and FDRs are important tools in investigation of aircraft accidents as the information retained by them can be used to generate computer animated videos, which enable investigators to visualize the last moments of a flight prior to the accident.

black-box-cutaway.gif
(Embedded from http://static.howstuffworks.com)
:
american587-animation.jpg
Example of animation image created using FDR data from American Airlines 587 that crashed in 2001.
(Embedded from http://www.aerospaceweb.org)

Parameters black boxes record

Black boxes record 88 mandatory parameters in 11 groups and they generally relate to:

  • Time (GMT or Elapsed)
  • Altitude
  • Airspeed
  • Vertical Acceleration
  • Magnetic Heading
  • Pitch Attitude
  • Roll Attitude
  • Flap Position
  • Power of each Engine
  • Time of each radio transmission
  • Control column position or control surface position

Here are some of the most common questions asked about Black box.

Q: What is its color?
A: Unlike the name of it, the colour of it is actually orange. The orange color makes it easier to locate on a crash site.

T790603A-707335.jpg (giantrobot.com)

Q: Is black box really indestructible?
A: This is still arguable. Although the box may have been damaged due to the crash, most of the times, the data inside it are still intact.
sarrrb.jpg (aviatingindia.wordpress)

Q: How safe are the data in the black box, is it fire proof?
A: Yes it is fireproof and waterproof as well, as the data are saved in crash survivable memory unit (CSMU). CSMU has power fail protection, Underwater locator replaceable battery, and is made of fireproof and waterproof material.

Q: What is it made of?
A: Titanium. It is one of the strongest materials on the earth.

Q: Why aren't aircraft made of black box material so that people would be safe inside even in a crash?
A: Black boxes are made of titanium. It would be extremely expensive, as well as heavy, to make a plane using this material. Besides, even if an aircraft was fuly made of titanium, when it crashes, the plane might be still intact, but the people inside it are still vulnerable, as the impact of a crash would be tremendous. The resulting G-forces would cause death due to internal injuries.

Q: Who invented it?
A: Dr Warren. He was a scientist at the Aeronautical Research Laboratory in Melbourne, Australia (Thomas, & Sydenham, 2007).

Q: Does every plane have it?
A: Most commercial aircraft do.

** Q: Is it a must to have black box on commercial plane?""
A: Yes it is, as investigators try to find the root causes of an accident so that similar accident will not happen again in the future.

Q: What information does it provide?
A: Pilot's conversation (up to thirty minutes of sound), Flight memory recorder, Flight memory electronics unit data, presure altitude, fuel flow, and so forth.
The picture below shows an example of data embedded from black box.
FOIA44.GIF (www.democraticunderground.com)

**Q: Can anyone read / understand the black box?
A: No. Only trained personnel who are able to do it.

Q: Where is it located?
A: At the rear of planes (normally in the tail). This position is believed to minimise the impact of crash.
we-are-marshall-2.jpg (howstuffworks.com)

Q: If a plane crashed on the ocean, is it still possible to find the black box?
A: Yes. All FDRs and CVRs are equipped with an underwater acoustical locator beacon. These beacons are cylindrical cases designed to withstand high impact shocks and deep water immersion up to 20,000ft. Essentially a beacon consists of a battery, an electronic module, a transducer and a water sensitive switch which actuates when immersed in water. The beacon radiates 37.5 kHz pulsed ultrasonic signals at a rate of once per second continuously. These signals can be tracked by vessels or divers equipped with directional receivers.
locate_flight_recorder.jpg
(Image embedded from www.marinebuzz.com)

_45871308_air_france_466.gif
(Image embedded from newsimg.bbc.co.uk)

Q: How long will the signal last?
A: About 30 days.

Q: Will it get tested before being placed on an aircraft?
A: Yes it will go through crash impact test, pin drop test, static crash test, fire test, deep-sea and salt water test, fluid immersion test (.howstuffworks)

See the video below for an example of pilots' conversation revealed by the black box

The video below shows how a black box is being opened.

What do CVRs reveal about communication in the cockpit?

In addition to possible technical problems, CVRs reveal how the pilots communicate with one another and others such as cabin crew and controllers. The ability to communicate with one another is paramount in flight safety. Communication enables information to be exchanged, mistakes to be pointed out and help solve problems. Unfortunately in numerous accidents, CVR recordings revealed a frightening inability of flight crew members to communicate. Situational awareness deteriorates when communication breaks down. This means that all pilots will be less aware of what is happening around them. The turning point came only after a KLM 747 collided with a Pan Am 747, where changes were made to so that the cockpit is less hierarchical. More emphasis was placed on teamwork, joint decision making and encouraging co-pilots to respectively question their captains. This concept is known as Crew Resource Management (CRM).

References

Thomas, R. & Sydenham, S. The Black Box Flight Recorder . [Online] www.kidcyber.com.au/topics/blackbox.html (2007) howstuffworks.com (1998)
National Transportation and Safety Board. Cockpit Voice Recorders (CVR) and Flight Data Recorders (FDR). Retrieved from http:// www.ntsb.gov/aviation/CVR_FDR.htm

Want to know more?

http://en.wikipedia.org/wiki/Flight_data_recorder
http://www.l-3ar.com/html/history.html

Technical Manual Underwater Acoustic Beacon : http://www.aviquipo.com/docs/61122%20TECH%20MANUAL%20DK100%20T&M%20140%20rev14.pdf.


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