Black Box :- Starting Point For Flight Investigations

INTRODUCTION:

In science, computing, and engineering, a black box is a device, system or object which can be viewed in terms of its inputs and outputs (or transfer characteristics), without any knowledge of its internal workings. Its implementation is "opaque" (black). Almost anything might be referred to as a black box:

To analyze something, as an open system, with a typical "black box approach", only the behavior of the stimulus/response will be accounted for, to infer the (unknown) box. The usual representation of this black box system is a data flow diagram centered in the box.

The opposite of a black box is a system where the inner components or logic are available for inspection, which is most commonly referred to as a white box (sometimes also known as a "clear box" or a "glass box").

What is a black box?

It's a device that helps air-crash investigators determine what went wrong, by providing a detailed record of a plane's final hours. Passenger jets normally carry two of these shoebox-size containers —

1) holding a voice recorder, which captures pilots' conversations

2) cockpit noise

3) another housing a data recorder, which logs the plane's speed, altitude, direction, fuel flow, hydraulic pressure, and hundreds of other metrics.

These steel-and-titanium black boxes — which, despite their name, are actually painted orange to make them easier to spot — are fire resistant, waterproof, and engineered to survive being smashed into the ground at over 300 mph. Most flight recorders are stored in the tail section of the aircraft, which is usually the last point of impact in a crash.

What is the black box made out of?

The "black box" is made up of two separate pieces of equipment:

the flight data recorder (FDR)
a cockpit voice recorder (CVR)

They are compulsory on any commercial flight or corporate jet and are usually kept in the tail of an aircraft, where they are more likely to survive a crash.

What color is the black box?

The term "black box" is almost never used within the flight safety industry or aviation, which prefers the term "flight recorder". The recorders are not permitted to be black in color and must be bright orange, as they are intended to be spotted and recovered after incidents.

History:(AIR FRANCE FLIGHT 447)

After the crash, they didn't find a single body for five days. Even with military and civilian personnel frantically scouring the seas, it was as if Air France Flight 447 had simply vanished over a remote area of ocean 600 miles from Brazil -- with 228 people onboard. It didn't happen in the early days of the airline industry; it occurred in 2009, on a fancy modern aircraft controlled by a competent company.

Airplane accidents are statistical rarities. But when they happen, they're often fatal, and people want answers as to why their loved ones died.

There are usually many unanswered questions as to what brought the plane down. Investigators turn to the airplane's flight data recorder (FDR) and cockpit voice recorder (CVR), also known as "black boxes," for answers. Following any airplane accident in the U.S., safety investigators from the National Transportation Safety Board (NTSB) immediately begin searching for the aircraft's black boxes.

It took investigators nearly two years to find the FDR from Flight 447. The box had not only survived an impact but also being submerged under nearly 13,000 feet of salty, corrosive seawater. In the end, the data proved that pilot error had contributed to a stall that eventually caused the crash.

These recording devices, which cost between $10,000 and $15,000 each, reveal details of the events immediately preceding the accident. In this article, we will look at the two types of black boxes, how they survive crashes, and how they are retrieved and analyzed.

How is it made??

1960’s

OLDER BLACK BOXES- Magnetic tape works like any tape recorder. The Mylar tape is pulled across an electromagnetic head, which leaves a bit of data on the tape.

1990’s

SOLID-STATE RECORDERS-

Much more reliable than the magnetic tape counterparts.
It uses stacked arrays, of memory chips with no moving parts.
Thus, it has fewer maintenance issues and decreased the chance of something breaking during a crash.are considered much more reliable than their magnetic-tape counterparts.
Data from both the CVR and FDR is stored on stacked memory boards inside the crash-survivable memory unit (CSMU). The memory boards have enough digital storage space to accommodate two hours of audio data for CVRs and 25 hours of flight data for FDRs.
Airplanes are equipped with sensors that gather data such as acceleration, airspeed, and altitude, flap settings, outside temperature, engine performance, and cabin temperature and pressure.
Magnetic tape recorders can track about 100 parameters, while solid-state recorders can track a lot more.

For instance, in the Boeing 787, the units can log a whopping 146,000 parameters, resulting in several terabytes of data for every single flight. That incredible load of data is a double-edged sword; it's great for monitoring the aircraft, but it can overwhelm engineers and maintenance personnel. To manage all of that data, they need sophisticated data management software.

Whether the system is an older version or fully modern, all of the data collected by the airplane's sensors is sent to the flight-data acquisition unit (FDAU) at the front of the aircraft. This device often is found in the electronic equipment bay under the cockpit.

The flight-data acquisition unit is the middle manager of the entire data-recording process. It takes the information from the sensors and sends it on to the black boxes.

Both black boxes are powered by one of two power generators that draw their power from the plane's engines. One generator is a 28-volt DC power source, and the other is an 115-volt, 400-hertz (Hz) AC power source.

COCKPIT VOICE RECORDERS

In almost every commercial aircraft, there are several microphones built into the cockpit that listens to flight crew conversation.

These microphones also track any ambient noise in the cockpit, such as switches being thrown or any knocks or thuds. There may be up to four microphones in the plane's cockpit, each connected to the cockpit voice recorder (CVR).

Microphones send audio to the CVR, which digitizes and stores the signals. In the cockpit, there is also a device called the associated control unit, which provides pre-amplification for audio going to the CVR. The four microphones are placed in the pilot's headset, co-pilot's headset, a headset of a third crew member (if there is a third crew member) and near the center of the cockpit, to pick up audio alerts and other sounds.

Most magnetic-tape CVRs store the last 30 minutes of sound. They use a continuous loop of tape that completes a cycle every 30 minutes. As new material is recorded, the oldest material is replaced. CVRs that use solid-state storage can record two hours of audio. Similar to the magnetic-tape recorders, solid-state recorders also record over old material.

FLIGHT DATA RECORDERS

The flight data recorder (FDR) is designed to record the operating data from the plane's systems. There are sensors wired from various areas on the plane to the flight-data acquisition unit, which is wired to the FDR. So whenever the pilot flips a switch or twiddles a knob, the FDR records each action.

In the U.S., the Federal Aviation Administration (FAA) requires that commercial airlines record a minimum of 11 to 29 parameters, depending on the size of the aircraft. Magnetic tape recorders have the potential to record up to 100 parameters. Solid-state FDRs can record hundreds or even thousands more.

On July 17, 1997, the FAA issued a Code of Federal Regulations that requires the recording of at least 88 parameters on aircraft manufactured after August 19, 2002. Here are a few of the parameters recorded by most FDRs:

Time
Pressure altitude
Airspeed
Vertical acceleration
Magnetic heading
Control-column position
Rudder-pedal position
Control-wheel position
Horizontal stabilizer
Fuel flow

Solid-state recorders can track more parameters than magnetic tape because they allow for a faster data flow. Solid-state FDRs can store up to 25 hours of flight data. Each additional parameter recorded by the FDR gives investigators one more clue about the cause of an accident.

BUILT TO SURVIVE

Airplane crashes are violent affairs. In many such accidents, the only devices that survive are the crash-survivable memory units (CSMUs) of the flight data recorders and cockpit voice recorders. Typically, the rest of the recorders' chassis and inner components are mangled. The CSMU is a large cylinder that bolts onto the flat portion of the recorder. This device is engineered to withstand extreme heat, jarring, crashes and tons of pressure. In older magnetic tape recorders, the CSMU is inside a rectangular box.

Using three layers of materials, the CSMU in a solid-state black box insulates and protects the stack of memory boards that store the digitized data.

Here's a closer look at the materials that provide a barrier for the memory boards, starting at the innermost barrier and working our way outward:

Aluminum housing -- There's a thin layer of aluminum around the stack of memory cards.
High-temperature insulation -- This dry-silica material is 1 inch (2.54 centimeters) thick and provides high-temperature thermal protection. This is what keeps the memory boards safe during post-accident fires.
Stainless-steel shell -- The high-temperature insulation material is contained within a stainless-steel cast shell that is about 0.25 inches (0.64 centimeters) thick. Titanium can be used to create this outer armor as well.

These hardened housings are incredibly important. Without adequate protection, all of the flight data would be destroyed. So to make sure that data stays safe, engineers attack their black boxes with full fury to see if their products can withstand extreme abuse.

THE FUTURE OF BLACK BOX

As technology continues to develop it is likely that Black Boxes, or flight data recorders, will become more and more sophisticated and more reliable, giving Air Crash Investigators more to go on when painstakingly trying to piece together what caused a plane crash.

Potentially, the humble MP3 player – adored by music fans the world over - could become part of the flight data recording software. In 2007, US light aircraft manufacturer LoPresti Speed Merchants announced that it planned to fully integrate the device as flight data recorder on all of its Fury piston aircraft. The company believes that if suitable software was used then MP3s would be capable of recording over 500 hours of flight time data.