INSIDE THE BLACK BOX

INSIDE THE BLACK BOX There were 111 aircraft accidents in 2014, the lowest in at least eight decades, according to the Bureau of Aircraft Accidents Archives. However, the year also saw the most deaths in aircraft accidents in almost 10 years- 1320. In March, Malaysia Airlines Flight MH370 mysteriously disappeared while flying over the South China Sea. In late December, Air Asia Flight QZ8501 crashed into the sea killing everyone on board, most likely due to bad weather. Every time there is an accident, talk eventually moves to the so-called black box carried by every plane. The black box records all key flight information, and can provide leads on what caused the accident. For instance, almost two years after it went missing over the Atlantic Ocean carrying 228 passengers, Air France Flight 447's black box was located using unmanned submarines in May 2011. Investigators found out the reasons for its crash-thunderstorms, speed systems icing over and the autopilot disengaging, confusing the pilots who lost control. Even with the recovery of the black box, it can take investigators months to piece together data and find out the cause of the accident. Without it, most flight mishaps will forever remain a mystery. HOW DO SEARCH PARTIES FIND THE BLACK BOX IF IT IS UNDERWATER? ALL YOU WANTED TO KNOW ABOUT THE BLACK BOX Why is it called a black box? The black box is not black at all, but bright orange, to aid investigators locate it easily. The origin of the name black box is perhaps due to the fact that initially flight recorders were photograph based- and the insides of those recorders were pitch dark. Also, flight recorders were often found in a charred state at crash sites, and journalists began calling them 'black boxes' 1 Crash: Airplane crashes into water What is it made of? The black box consists of two separate units- the cockpit voice recorder (CVR) and the flight data recorder (FDR). The recorded information is stored inside solid state memory boards housed inside crash survivable memory units (CMSU). The memory boards can store up to 25 hours of flight time data and up to 2 hours of cockpit sound, with new data replacing the old data continuously. 2 Pinger. A wet button in the underwater locator beacon (ULB) is activated as soon as the black box touches water, enabling the lithium battery to get activated. COCKPIT VOICE RECORDER (CVR) FLIGHT DATA RECORDER (FDR) 6 Signal detectors: This signal can be detected by hand-held, towed, or ship-mounted ULB receivers. POWER SUPPLY STEEL HOUSING 32cm 49.7cm What information is stored in these units? CVR records the conversation of the crew and any sounds within the cockpit that may provide vital clues on what went wrong minutes before the flight malfunctioned or crashed. • STACK OF MEMORY BOARDS FDR records nearly 300 operating parameters of a plane at every point of time including altitude, speed, direction of flight, movement of wings, autopilot, fuel supplies and even the status of on-board smoke alarms. Skilled investigators use information recorded in these units to zero in on the cause of the crash. 6 Underwater microphone: A hydrophone in pinger locators works as an underwater mic as it is made of materials capable of converting sound signals into an electrical signal. AIRCRAFT INTERFACE CIRCUIT BOARDS Can black boxes withstand the impact of a crash? The most indestructible part of the black box is CSMU, which has a heavy stainless steel or titanium shell that is wrapped with insulating material. The memory unit can withstand up to 3,400 times the force of gravity and exposure to temperatures over 1,100 degrees Celsius for an hour, and pressure at 20,000 feet underwater. Flight recorders are generally kept in the aircraft's tail, which suffers the least impact in the event of a crash. 4 Amplified signal: Printed circuit board assembly helps produce a pulse with the desired characteristics. INSULATION THERMAL BLOCK 3 Acoustic Signal: The ULB sends one acoustic signal at 37.5 kilohertz (kHz) once every second for 30 days, which can be detectable from up to 5km from the surface. UNDERWATER LOCATER BEACON FLIGHT RECORDER OCEAN-BED WHY ARE THEY DIFFICULT TO FIND? (Drawings are not to scale.) • Pinger has a battery life of only 30 days ORange of acoustic signal is between 1km and 5km OAs big as a shoe box HOW THE BLACK BOX CAME ABOUT Black boxes or data recorders have existed since the beginning of manned flights, and have evolved over the years to withstand tougher conditions and absorb more data. Here is a look at the history of the black box 1903: In the world's first manned aircraft, the Wright Brothers installed a device to record 1963: Edmund A. Boniface got the US patent for a cockpit recorder which could record the voices of the persons in the cockpit and any other sounds in the front of the aircraft. Using microphones in the cockpit for magnetic recording, the recorder was kept in a shockproof, waterproof and fireproof container. 1960s: Crash- 1953: David Warren, an Australian chemist from Aeronautical Research Laboratories (ARL) was part of the accident investigations into the crash of the world's first jet-powered commercial aircraft, the Comet. Using a miniphone wire recorder as basis, he and his colleagues found a way to put flight data as well as voice recording on the wire, thus inventing the first CVR, called the ARL Flight Memory Recorder. protected FDRS and CVRS became mandatory on airliners around the world. parameters like propeller rotation and airspeed. 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 1927: In his historical trans-Atlantic flight called the Spirit of St. Louis, Charles Lindbergh used a more evolved version that had a barograph (pressure monitor) which marked ink on paper wrapped around a rotating drum This instrument was kept in a small wooden box. 6 1953: JJ. Ryan was credited with the US patent for the flight recorder described as a device for continu- ously recording velocity, vertical acceleration and altitude through the flight. The measurements were slowly inscribed on a moving strip of aluminium foil. 1990s: For many years, FDRS and CVRS would use metal tape and then eventually magnetic tape with high survivability to record digital data. By the early 1990s, CVRS and FDRS had started storing data in computer memory using solid-state memory boards. Advantages are more memory storage, and no moving parts to get damaged. They are used in all modern aircraft. Graphic by Yatish Asthana/Mint Compiled by Sayantan Bera and Nikita Mehta