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2674.

2467) Eiffel Tower

Gist

The Eiffel Tower is famous for being an engineering marvel, the former tallest structure in the world, and a powerful, romantic symbol of Paris and France, initially built for the 1889 World's Fair but becoming a beloved icon through its unique design, stunning lights, and representation of French ingenuity and culture. 

The most famous tourist attraction in France (and one of the best known in the world), the Eiffel Tower is 135 years old and is still considered a symbol of modernity and avant-garde in Paris.

Summary

On March 31, 1889, the Eiffel Tower is dedicated in Paris in a ceremony presided over by Gustave Eiffel, the tower’s designer, and attended by French Prime Minister Pierre Tirard, a handful of other dignitaries and 200 construction workers.

In 1889, to honor of the centenary of the French Revolution, the French government planned an international exposition and announced a design competition for a monument to be built on the Champ-de-Mars in central Paris. Out of more than 100 designs submitted, the Centennial Committee chose Eiffel’s plan of an open-lattice wrought-iron tower that would reach almost 1,000 feet above Paris and be the world’s tallest man-made structure. Eiffel, a noted bridge builder, was a master of metal construction and designed the framework of the Statue of Liberty that had recently been erected in New York Harbor.

Eiffel’s tower was greeted with skepticism from critics who argued that it would be structurally unsound, and indignation from others who thought it would be an eyesore in the heart of Paris. Unperturbed, Eiffel completed his great tower under budget in just two years. Only one worker lost his life during construction, which at the time was a remarkably low casualty number for a project of that magnitude. The light, airy structure was by all accounts a technological wonder and within a few decades came to be regarded as an architectural masterpiece.

The Eiffel Tower is 984 feet tall and consists of an iron framework supported on four masonry piers, from which rise four columns that unite to form a single vertical tower. Platforms, each with an observation deck, are at three levels. Elevators ascend the piers on a curve, and Eiffel contracted the Otis Elevator Company of the United States to design the tower’s famous glass-cage elevators.

The elevators were not completed by March 31, 1889, however, so Gustave Eiffel ascended the tower’s stairs with a few hardy companions and raised an enormous French tricolor on the structure’s flagpole. Fireworks were then set off from the second platform. Eiffel and his party descended, and the architect addressed the guests and about 200 workers. In early May, the Paris International Exposition opened, and the tower served as the entrance gateway to the giant fair.

The Eiffel Tower remained the world’s tallest man-made structure until the completion of the Chrysler Building in New York in 1930. Incredibly, the Eiffel Tower was almost demolished when the International Exposition’s 20-year lease on the land expired in 1909, but its value as an antenna for radio transmission saved it. It remains largely unchanged today and is one of the world’s premier tourist attractions.

Details

The Eiffel Tower is a wrought-iron lattice tower on the Champ de Mars in Paris, France. It is named after the engineer Gustave Eiffel, whose company designed and built the tower from 1887 to 1889.

Locally nicknamed "La dame de fer" (French for "Iron Lady"), it was constructed as the centrepiece of the 1889 World's Fair, and to crown the centennial anniversary of the French Revolution. Although initially criticised by some of France's leading artists and intellectuals for its design, it has since become a global cultural icon of France and one of the most recognisable structures in the world. The tower received 5,889,000 visitors in 2022. The Eiffel Tower is the most visited monument with an entrance fee in the world: 6.91 million people ascended it in 2015. It was designated a monument historique in 1964, and was named part of a UNESCO World Heritage Site ("Paris, Banks of the Seine") in 1991.

The tower is 330 metres (1,083 ft) tall, about the same height as an 81-storey building, and the tallest structure in Paris. Its base is square, measuring 125 metres (410 ft) on each side. During its construction, the Eiffel Tower surpassed the Washington Monument to become by far the tallest human-made structure in the world, a title it held for 41 years until the Chrysler Building in New York City was finished in 1930. It was the first structure in the world to surpass both the 200-metre and 300-metre mark in height. Due to the addition of a broadcasting aerial at the top of the tower in 1957, it is now taller than the Chrysler Building by 5.2 metres (17 ft). Excluding transmitters, the Eiffel Tower is the second tallest free-standing structure in France after the Millau Viaduct.

The tower has three levels for visitors, with restaurants on the first and second levels. The top level's upper platform is 276 m (906 ft) above the ground—the highest public observation deck in the European Union. Tickets can be purchased to ascend by stairs or lift to the first and second levels. The climb from ground level to the first level is over 300 steps, as is the climb from the first level to the second, making the entire ascent a 600-step climb. Although there is a staircase to the top level, it is usually accessible only by lift. On this top, third level, is a private apartment built for Gustave Eiffel, who decorated it with furniture made by Jean Lachaise and invited friends such as Thomas Edison.

Additional Information

Eiffel Tower, wrought-iron structure in Paris that is among the most famous landmarks in the world. It is also a technological masterpiece in building-construction history. It was designed and built (1887–89) by Gustave Eiffel and named in his honor.

Background and construction

When the French government was organizing the International Exposition of 1889 to celebrate the centenary of the French Revolution, a competition was held for designs for a suitable monument. More than 100 plans were submitted, and the Centennial Committee accepted that of the noted bridge engineer Gustave Eiffel. Eiffel’s concept of a 300-meter (984-foot) tower built almost entirely of open-lattice wrought iron aroused amazement, skepticism, and no little opposition on aesthetic grounds. When completed, the tower served as the entrance gateway to the exposition.

Nothing remotely like the Eiffel Tower had ever been built; it was twice as high as the dome of St. Peter’s in Rome or the Great Pyramid of Giza. In contrast to such older monuments, the tower was erected in only about two years (1887–89), with a small labor force, at slight cost. Making use of his advanced knowledge of the behavior of metal arch and metal truss forms under loading, Eiffel designed a light, airy, but strong structure that presaged a revolution in civil engineering and architectural design. And, after it opened to the public on May 15, 1889, it ultimately vindicated itself aesthetically.

Description and dimensions

The Eiffel Tower stands on four lattice-girder piers that taper inward and join to form a single large vertical tower. As they curve inward, the piers are connected to each other by networks of girders at two levels that afford viewing platforms for tourists. By contrast, the four semicircular arches at the tower’s base are purely aesthetic elements that serve no structural function. Because of their unique shape, which was dictated partly by engineering considerations but also partly by Eiffel’s artistic sense, the piers required elevators to ascend on a curve; the glass-cage machines designed by the Otis Elevator Company of the United States became one of the principal features of the building.

After the 1889 fair closed, Eiffel realized that the only way to save his monument would be to find new and profitable uses for it. He supervised changes to accommodate a meteorological station in 1890, a military telegraph station in 1903, and a laboratory for studying aerodynamics in 1909. Further modifications were made for the expositions of 1900, 1925, and 1937. Additions made for television transmission added about 20 meters (66 feet) to the height.

The tower stands 300 meters (984 feet) high. It rests on a base that is 5 meters (17 feet) tall, and the TV antenna atop the tower gives it a total elevation of 330 meters (1,083 feet). The Eiffel Tower was the tallest structure in the world until the topping off of the Chrysler Building in New York City in 1929.

Tourist attraction

The Eiffel Tower is arguably the most popular paid attraction in world. Some seven million people visit it each year. The tower features a museum, several restaurants, and the Gustave Eiffel Reception Room, which provides space for business conferences, expositions, cultural events, and social gatherings. In addition, several eateries and various shops are housed in the tower. An observation deck is located just under the antenna, at a height of 276 meters (906 feet).

2466) Blood falls

Gist

Blood Falls is truly one of the most exciting spots to visit in Antarctica, which is best visited by boat. It gets its name because it's a waterfall that happens to be a shockingly-bright red color, similar to blood. However, the red color is thought to come from iron.

Blood Falls is a unique landform, as it did not originate from glacial melted water typically found in other continental glaciers. Instead a cascade of iron rich hypersaline water, originally trapped underground for millions of years, escaped to the Earth's surface via fissures under Taylor Glacier in East Antarctica.

Summary:

Where is Blood Falls located?

• Blood Falls, is located in Taylor Valley.
• Taylor Valley is one of the McMurdo Dry Valleys (MDV) in the Transantarctic Mountains. It is located between Asgard Range in the north and Kukri Hills in the south, containing numerous glaciers, lakes and rivers.
• Approximately 29 kilometres long, Taylor Valley extends from the retreating Taylor Glacier in the west to McMurdo Sound in the east.
• Subglacial water flows to Earth’s surface from the terminus of Taylor Glacier onto ice covered Lake Bonney in Taylor Valley.

What is the environment surrounding Blood Falls?:

Climate

Taylor Valley, one of the McMurdo Dry Valleys (MDV), encounters a freezing desert environment.  Located in a rain shadow area behind mountains, the valleys experience low precipitation, mean annual temperature -19.8°C, and strong katabatic winds that reach 320 kilometres per hour. The winds evaporate all moisture, hence hindering the formation of ice and snow that covers most of Antarctica.

Taylor Valley and the other MDV encompass the largest ice-free region in Antarctica, with a combined area of Sq km 4500. The average moisture is less than 6mmpa, generally falling in the form of snow and summer glacial melt.

How was Blood Falls formed?

During a geological period called the Pliocene Epoch, about five million years ago, global warming caused East Antarctica’s ice sheets to melt and sea levels to rise about 20 metres. Taylor Valley was flooded and developed into a deep fiord.

• Around 5 million years ago sea levels rose, flooding East Antarctica. This created a salty inland lake
• Around 3 million years later, glaciers formed over the saline lake
• Around 2 million years ago a sub-glacial lake of saltwater became trapped and isolated. The frozen glacier surrounding the lake acted as a ‘time capsule’, preserving microbial species.

Research from University of Alaska, calculates that salt water took approximately 1.5 million years to finally reach Blood Falls as it made its way through fissures and channels in the glacier.

What caused the red colour in Blood Falls?

• Earliest explorers noticed the stain at the terminus of the glacier and speculated that red algae was responsible for the bright colour. Investigations later found the water was unsuitable for the growth and survival of algae.
• In 2009, scientists discovered the red colour was due to high levels of iron oxide in saltwater from a network of subglacial rivers and a subglacial lake.

Details

Blood Falls is an outflow of an iron(III) oxide–tainted plume of saltwater, flowing from the tongue of Taylor Glacier onto the ice-covered surface of West Lake Bonney in the Taylor Valley of the McMurdo Dry Valleys in Victoria Land, East Antarctica.

Iron-rich hypersaline water sporadically emerges from small fissures in the ice cascades. The saltwater source is a subglacial pool of unknown size overlain by about 400 metres (1,300 ft) of ice, several kilometers from its tiny outlet at Blood Falls.

The reddish deposit was found in 1911 by the Australian geologist Thomas Griffith Taylor, who first explored the valley that bears his name. The Antarctica pioneers first attributed the red color to red algae, but later it was proven to be due to iron oxides.

Geochemistry

Poorly soluble hydrous ferric oxides are deposited at the surface of ice after the ferrous ions present in the unfrozen saltwater are oxidized in contact with atmospheric oxygen. The more soluble ferrous ions initially are dissolved in old seawater trapped in an ancient pocket remaining from the Antarctic Ocean when a fjord was isolated by the glacier in its progression during the Miocene period, some 5 million years ago, when the sea level was higher than today.

Unlike most Antarctic glaciers, the Taylor Glacier is not frozen to the bedrock, probably because of the presence of salts concentrated by the crystallization of the ancient seawater imprisoned below it. Salt cryo-concentration occurred in the deep relict seawater when pure ice crystallized and expelled its dissolved salts as it cooled down because of the heat exchange of the captive liquid seawater with the enormous ice mass of the glacier. As a consequence, the trapped seawater was concentrated in brines with a salinity two to three times that of the mean ocean water. A second mechanism sometimes also explaining the formation of hypersaline brines is the water evaporation of surface lakes directly exposed to the very dry polar atmosphere in the McMurdo Dry Valleys. The analyses of stable isotopes of water allow, in principle, to distinguish between both processes as long as there is no mixing between differently formed brines.

Hypersaline fluid, sampled fortuitously through a crack in the ice, was oxygen-free and rich in sulfate and ferrous ion. Sulfate is a remnant geochemical signature of marine conditions, while soluble divalent iron was likely liberated under reducing conditions from the subglacial bedrock minerals weathered by microbial activity.

Microbial ecosystem

Chemical and microbial analyses both indicate that a rare subglacial ecosystem of autotrophic bacteria developed that metabolizes sulfate and ferric ions. According to geomicrobiologist Jill Mikucki at the University of Tennessee, water samples from Blood Falls contained at least 17 different types of microbes, and almost no oxygen. An explanation may be that the microbes use sulfate to respire with ferric ions and metabolize the trace levels of organic matter trapped with them. Such a metabolic process had never before been observed in nature.

A puzzling observation is the coexistence of ferrous and sulfate ions under anoxic conditions. No sulfide anions are found in the system. This suggests an intricate and poorly understood interaction between the sulfur and the iron biochemical cycles.

In December 2014, scientists and engineers led by Mikucki returned to Taylor Glacier and used a probe called IceMole, designed by a German collaboration, to melt into the glacier and directly sample the salty water (brine) that feeds Blood Falls.

Samples were analyzed, and revealed a cold (−7 °C (19 °F)), iron-rich (3.4 mM) subglacial brine (8% sodium chloride). From these samples, scientists isolated and characterized a type of bacteria capable of growing in salty water (halophilic), that thrives in the cold (psychrophile), and is heterotrophic, which they assigned to the genus Marinobacter. DNA bioinformatic analysis indicated the presence of at least four gene clusters involved in secondary metabolism. Two gene clusters are related to the production of aryl polyenes, which function as antioxidants that protect the bacteria from reactive oxygen species. Another gene cluster seems to be involved in terpene biosynthesis, most likely to produce pigments. Other bacteria identified are Thiomicrospira sp., and Desulfocapsa sp.

Implications for the Snowball Earth hypothesis

According to Mikucki et al. (2009), the now-inaccessible subglacial pool was sealed off 1.5 to 2 million years ago and transformed into a kind of "time capsule", isolating the ancient microbial population for a sufficiently long time to evolve independently of other similar marine organisms. It explains how other microorganisms could have survived when the Earth (according to the Snowball Earth hypothesis) was entirely frozen over.

Ice-covered oceans might have been the only refugium for microbial ecosystems when the Earth apparently was covered by glaciers at tropical latitudes during the Proterozoic eon about 650 to 750 million years ago.

Implications for astrobiology

This unusual place offers scientists a unique opportunity to study deep subsurface microbial life in extreme conditions without the need to drill deep boreholes in the polar ice cap, with the associated contamination risk of a fragile and still-intact environment.

The study of harsh environments on Earth is useful to understand the range of conditions to which life can adapt and to advance assessment of the possibility of life elsewhere in the Solar System, in places such as Mars or Europa, an ice-covered moon of Jupiter. Scientists of the NASA Astrobiology Institute speculate that these worlds could contain subglacial liquid water environments favorable to hosting elementary forms of life, which would be better protected at depth from ultraviolet and cosmic radiation than on the surface.

Additional Information

Amid Antarctica’s vast stretches of glittering white snow and ethereal blue glacier ice is the famous Blood Falls. It’s situated at the terminus of Taylor Glacier in the McMurdo Dry Valleys. Blood Falls is an iron-rich, hypersaline discharge phenomenon. And it spews bold streaks of bright-red brine from within the glacier onto the ice-covered surface of Lake Bonney.

Australian geologist Griffith Taylor was the first explorer to happen upon Blood Falls in 1911. It was during one of the earliest Antarctic expeditions. At the time, Taylor (incorrectly) attributed the color to the presence of red algae. The cause of this color was a mystery for nearly a century. But now we know that the iron-rich liquid turns red when it breaches the surface and oxidizes. In fact, this is the same process that gives iron a reddish hue when it rusts.

Blood Falls, named for its ruddy color, is not in fact a gush of blood from some unseen wound.

The color was initially chalked up to red algae, but a study in the Journal of Glaciology has uncovered its true origin using radar to scan the layers of ice from which the river pours.

The discovery came at the hands of a team of scientists, including National Geographic emerging explorer Erin C Pettit.

Located in Antarctica’s McMurdo Dry Valleys, the falls pour forth from Taylor Glacier, and the liquid bubbles up from fissures in the glacier’s surface. The flow was previously a mystery, as the mean temperature is 1.4 degrees Fahrenheit (-17 degrees Celsius) and little glacial melting can be seen at the surface.

Imaging from underneath the glacier helped solve the mystery, revealing a complex network of subglacial rivers and a subglacial lake—all filled with brine high in iron, giving the falls its reddish tint.

According to the study, the makeup of the brine explains the fact that it flows instead of freezes.

“The brine remains liquid within the subglacial and englacial environments through latent heat of freezing coupled with elevated salt content,” the study explains.

Iron-Filled, Salty Water

The lake under the glacier has an unusually salty consistency, and because saltwater has a lower freezing point than pure water and releases heat as it freezes, it melts the ice, enabling the rivers to flow.

This means that the glacier can support flowing water and also that this is the coldest glacier on Earth with constantly flowing water—though this water is so filled with iron that it looks like something else entirely.

The study also measured the amount of iron-rich brine in the river water and found the brine content increased as the measurements drew closer to the falls.

Water temperature and brine content were also found to be related: Cracks of various sizes in the glacier let brine into the glacier. Then the brine (pictured here in red to represent the amount of iron present in the water) begins to freeze, and the latent heat warms the ice around it, upping the brine concentration in the center of the cracks.

2465) Brainstem

Gist

The brainstem is the structure that connects the cerebrum of the brain to the spinal cord and cerebellum. It is composed of three sections in descending order: the midbrain, pons, and medulla oblongata.

The brainstem is the vital stalk-like structure connecting the cerebrum and cerebellum to the spinal cord, controlling essential life functions like breathing, heart rate, blood pressure, and consciousness, while also relaying sensory/motor signals and housing nuclei for most cranial nerves (III-XII). It's made of three parts—the midbrain, pons, and medulla oblongata—and is crucial for sleep, balance, swallowing, vision, hearing, and facial movement. 

Summary

The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain, the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is continuous with the thalamus of the diencephalon through the tentorial notch, and sometimes the diencephalon is included in the brainstem.

The brainstem is very small, making up around only 2.6 percent of the brain's total weight. It has the critical roles of regulating heart and respiratory function, helping to control heart rate and breathing rate. It also provides the main motor and sensory nerve supply to the face and neck via the cranial nerves. Ten pairs of cranial nerves come from the brainstem. Other roles include the regulation of the central nervous system and the body's sleep cycle. It is also of prime importance in the conveyance of motor and sensory pathways from the rest of the brain to the body, and from the body back to the brain. These pathways include the corticospinal tract (motor function), the dorsal column-medial lemniscus pathway (fine touch, vibration sensation, and proprioception), and the spinothalamic tract (pain, temperature, itch, and crude touch).

Clinical significance

Diseases of the brainstem can result in abnormalities in the function of cranial nerves that may lead to visual disturbances, pupil abnormalities, changes in sensation, muscle weakness, hearing problems, vertigo, swallowing and speech difficulty, voice change, and co-ordination problems. Localizing neurological lesions in the brainstem may be very precise, although it relies on a clear understanding on the functions of brainstem anatomical structures and how to test them.

Brainstem stroke syndrome can cause a range of impairments including locked-in syndrome.

Duret haemorrhages are areas of bleeding in the midbrain and upper pons due to a downward traumatic displacement of the brainstem.

Cysts known as syrinxes can affect the brainstem, in a condition, called syringobulbia. These fluid-filled cavities can be congenital, acquired or the result of a tumor.

Criteria for claiming brainstem death in the UK have developed in order to make the decision of when to stop ventilation of somebody who could not otherwise sustain life. These determining factors are that the patient is irreversibly unconscious and incapable of breathing unaided. All other possible causes must be ruled out that might otherwise indicate a temporary condition. The state of irreversible brain damage has to be unequivocal. There are brainstem reflexes that are checked for by two senior doctors so that imaging technology is unnecessary. The absence of the cough and gag reflexes, of the corneal reflex and the vestibulo-ocular reflex need to be established; the pupils of the eyes must be fixed and dilated; there must be an absence of motor response to stimulation and an absence of breathing marked by concentrations of carbon dioxide in the arterial blood. All of these tests must be repeated after a certain time before death can be declared.

Details

Your brainstem connects your brain to your spinal cord. It sits at the bottom of your brain and includes the midbrain, pons and medulla oblongata. Your brainstem sends messages to the rest of your body to regulate balance, breathing, heart rate and more.

What is the brainstem?

Your brainstem connects your brain to your spinal cord. It sits near the bottom of your brain. It helps regulate vital body functions that you don’t have to think about, like breathing and your heart rate. Your brainstem also helps with your balance, coordination and reflexes.

It’s part of your central nervous system and has three parts that work together. Each part does a specific job to help you adapt to your environment, move and function.

Function:

What is the function of the brainstem?

Your brainstem sends messages back and forth between your brain and other parts of your body. It regulates many involuntary actions — functions your body performs automatically, like:

* Balance.
* Blood pressure.
* Breathing.
* Eye movements.
* Facial movements and sensations.
* Hearing.
* Heart rate.
* Sleep and wakefulness.
* Swallowing.
* Taste.

What are brainstem reflexes?

Brainstem reflexes are your body’s immediate and involuntary motor responses that help you survive and adapt to changes in your environment. You aren’t consciously thinking about performing these actions. Instead, your brainstem automatically tells your body to do them.

Brainstem reflexes include:

* Cardiovascular reflexes: A group of reflexes that regulate your heartbeat and blood pressure.
* Gag reflex: This reflex protects your airways.
* Swallowing reflex: This reflex moves food and liquids from your mouth to your stomach.
* Pupillary light reflex: This adjusts the size of your pupil (the black center of your eye) to adapt to lighting changes.
* Vestibulo-ocular reflex: This reflex steadies your eyes when you move your head or the rest of your body.
* Respiratory reflexes: A group of reflexes that regulate breathing, coughing and sneezing.

Anatomy:

Where is the brainstem located?

Your brainstem is located near the bottom of your brain, at the back of your skull. It connects your brain to your spinal cord.

What are the three parts of the brainstem?

Your brainstem is made up of three parts:

* Midbrain: The top part of your brainstem. The midbrain is involved in several functions, including motor control, particularly eye movements and processing of vision and hearing.
* Pons: The middle portion of your brainstem that coordinates face and eye movements, facial sensations, hearing and balance.
* Medulla oblongata: The bottom part of your brainstem that regulates your breathing, heartbeat, blood pressure and swallowing.

Your brainstem also contains your reticular activating system (RAS). The RAS is a network of neurons (nerve cells that carry electrical signals and chemicals through your brain). It works with your thalamus to manage your:

* Wakefulness (alertness).
* Awareness of your surroundings.
* Sleep and wake cycles.

Brainstem cranial nerves

Your brainstem contains 10 of the 12 cranial nerves (nerves that start in your brain) including cranial nerves 3 through 12. They help with your movements, sensations, taste and hearing.

What does the brainstem look like?

Your brainstem looks like a flower stalk or a stem of a plant. It’s a tube-like structure made of neural (or nervous system) tissue. It’s about 2 to 3 inches (5 to 7 centimeters) long.

Additional Information

Brainstem is area at the base of the brain that lies between the deep structures of the cerebral hemispheres and the cervical spinal cord and that serves a critical role in regulating certain involuntary actions of the body, including heartbeat and breathing. The brainstem is divided into three sections in humans: the midbrain (mesencephalon), the pons (metencephalon), and the medulla oblongata (myelencephalon).

The brainstem houses many of the control centres for vital body functions, such as swallowing, breathing, and vasomotor control. All of the cranial nerve nuclei, except those associated with olfaction and vision, are located in the brainstem, providing motor and sensory function to structures of the cranium, including the facial muscles, tongue, pharynx, and larynx, as well as supplying the senses of taste, equilibrium, and hearing. The brainstem also has nuclei important for sympathetic and parasympathetic autonomic functions. All efferent and afferent pathways between the cerebrum and cerebellum course through the brainstem, and many of them decussate, or cross, within this structure.

Because of the important neural structures concentrated in this small portion of the nervous system, even very small lesions of the brainstem may have profound effects. Speech disorders, vestibular disturbance, abnormal consciousness, dysphagia, and respiratory disturbance are a few examples of possible outcomes of brainstem disorders. Such disorders can be caused by trauma, tumours, strokes, infections, and demyelination (multiple sclerosis). Complete loss of brainstem function is regarded by some experts as equivalent to brain death.

2463) Flight Data Recorder

Gist

A flight data recorder (FDR), part of the "black box," is a rugged device that records crucial aircraft operational data (altitude, speed, heading, etc.) and audio (CVR) for accident investigation, designed to survive extreme impacts, heat, and water to help determine crash causes and improve aviation safety, with modern units capturing 25+ hours of info in bright orange, crash-survivable casings with locator beacons. 

A flight data recorder (FDR; also ADR, for accident data recorder) is an electronic device employed to record instructions sent to any electronic systems on an aircraft. The data recorded by the FDR are used for accident and incident investigation.

Summary

A flight recorder is an electronic recording device placed in an aircraft for the purpose of facilitating the investigation of aviation accidents and incidents. The device may be referred to colloquially as a "black box", an outdated name which has become a misnomer because they are required to be painted bright orange, to aid in their recovery after accidents.

There are two types of flight recording devices: the flight data recorder (FDR) preserves the recent history of the flight by recording of dozens of parameters collected several times per second; the voice recorder (CVR) preserves the recent history of the sounds in the math, including the conversation of the pilots. The two devices may be combined into a single unit. Together, the FDR and CVR document the aircraft's flight history, which may assist in any later investigation.

The two flight recorders are required by the International Civil Aviation Organization to be capable of surviving conditions likely to be encountered in a severe aircraft accident. They are specified to withstand an impact of 3400 g and temperatures of over 1,000 °C (1,830 °F) by EUROCAE ED-112. They have been a mandatory requirement in commercial aircraft in the United States since 1967. After the unexplained disappearance of Malaysia Airlines Flight 370 in 2014, commentators have called for live streaming of data to the ground, as well as extending the battery life of the underwater locator beacons.

Details

Flight Data Recorder (FDR) - device used to record specific aircraft performance parameters. The purpose of an FDR is to collect and record data from a variety of aircraft sensors onto a medium designed to survive an accident.

An FDR has historically been one of two types of "flight recorder" carried on aircraft, the other being a math voice recorder (CVR). Where both types of recorder are fitted, they are now sometimes combined into a single unit (ICAO Definition: Combination recorders). Combination recorders need to meet the flight recorder equipage requirements as specifically detailed in ICAO Annex 6 - Operation of Aircraft.

These combination recorders are sometimes referred to as Digital Voice and Data Recorders (DVDR). Some models originally recorded 25 hours of flight data and two hours of audio. However, rules adopted by the International Civil Aviation Organisation (ICAO) and the European Union Aviation Safety Agency (EASA) require 25 hours of audio for commercial aircraft with a maximum takeoff weight of 27,000 kg (60,000 lbs) or more, manufactured after January 1, 2021.

Some regulators require a minimum of two DVDRs. For example, U.S. Federal Aviation Administration (FAA) regulations state: "Two separate recorders are required for airplanes. Therefore, a single combination CVR/DFDR may not serve as both the required DFDR and the required CVR." However, the FAA allows one combination unit on rotorcraft, as long as no single electrical failure can disable both the CVR and DFDR functions. The FAA also plans a 25-hour CVR requirement.

Other ICAO Requirements

According to the provisions in ICAO Annex 6 - Operation of Aircraft, Vol 1 and Vol. III, a Type I FDR shall shall record the parameters required to determine accurately the aeroplane flight path, speed, attitude, engine power, configuration and operation. Types II and IIA FDRs shall record the parameters required to determine accurately the aeroplane flight path, speed, attitude, engine power and configuration of lift and drag devices.

The detailed list of parameters to be recorded by FDRs is provided in section 6.3 “Flight recorders” and at Attachement D to Annex 6, Vol. I. Furthermore, provisions in section 6.3 specify the aircraft equipage requirements depending on the maximum certificated takeoff mass and the date of first issue of the individual certificate of airworthiness. For example, provision 6.3.6 of Annex 6, Vol. I states that, all aeroplanes of a maximum certificated takeoff mass of over 5,700 kg for which the individual certificate of airworthiness is first issued after 1 January 2005 shall be equipped with a Type IA FDR.

According to ICAO SARPS, combination recorders (FDR/CVR) can only be used to meet the flight recorder equipage requirements as specifically indicated in ICAO Annex 6 (Vol I and Vol III, Attachment D).

Annex 6 amendments that took effect in 2019 state that FDR and CVR data may be used only for safety-related purposes with appropriate safeguards, and for criminal proceedings.

Other FAA Requirements

U.S. Federal Aviation Administration (FAA) requirements regarding FDRs for transport category aircraft include the following provisions:

* The FDR receives electrical power from a bus that provides maximum reliability without jeopardising service to essential or emergency loads.
* The FDR remains powered for as long as possible without jeopardising emergency operation of the airplane.
* There is an aural or visual means for preflight checking of the recorder for proper recording of data in the storage medium.
* Any single electrical failure does not disable both the FDR and the CVR.
* Each recorder must be bright orange or bright yellow, must have reflective tape attached, and have an underwater locating device.
* The FDR is supplied with flight data that meets specified accuracy requirements.

Objective

The recorder is installed in the most crash survivable part of the aircraft, usually the tail section. The data collected in the FDR system can help investigators determine whether an accident was caused by pilot error, by an external event (such as windshear), or by an airplane system problem. Furthermore, these data have contributed to airplane system design improvements and the ability to predict potential difficulties as airplanes age. An example of the latter is using FDR data to monitor the condition of a high-hours engine. Evaluating the data could be useful in making a decision to replace the engine before a failure occurs.

Additional Information

A flight recorder is an instrument that records the performance and condition of an aircraft in flight. Governmental regulatory agencies require these devices on commercial aircraft to make possible the analysis of crashes or other unusual occurrences. Flight recorders actually consist of two functional devices, the flight data recorder (FDR) and the voice recorder (CVR), though sometimes these two devices are packaged together in one combined unit. The FDR records many variables, not only basic aircraft conditions such as airspeed, altitude, heading, vertical acceleration, and pitch but also hundreds of individual instrument readings and internal environmental conditions. The CVR records verbal communication between crew members within the aircraft’s math as well as voice transmissions by radio. Aircraft sounds audible in the math are also caught on the recorder. Flight recorders are commonly carried in the tail of the aircraft, which is usually the structure that is subject to the least impact in the event of a crash. In spite of the popular name black box, flight recorders are painted a highly visible vermilion colour known as “international orange.”

The voice and instrument data processed by the flight recorder are stored in digital format on solid-state memory boards. At least 2 hours of math sound and up to 25 hours of flight data are stored, new data continuously replacing the old. The memory boards are housed within a box or cylinder called the crash-survivable memory unit. This is the only truly survivable component of the flight recorder; the other components, such as the data processor, are not necessary for retrieval of data. Consisting of a heavy stainless steel shell wrapped within layers of insulating material and covered by an aluminum housing, a memory unit is expected to survive impacts of 3,400 g (units of gravitational acceleration), flame temperatures as high as 1,100 °C (2,000 °F), and pressures encountered at 6,000 metres (20,000 feet) underwater. In the event of a crash at sea, flight recorders are equipped with a sonar device that is designed to emit an ultrasonic locator signal for at least 30 days.

In 1939 French engineers François Hussenot and Paul Beaudouin invented a flight recorder, the “type HB” (later called the “hussenograph”), that recorded altitude and speed information on a piece of photographic film. During World War II, analyzing crashes of military aircraft became important. In the United Kingdom, engineers Len Harrison and Vic Husband developed a system that recorded aircraft data on copper foil and could survive a crash. In Finland, engineer Veijo Hietala in 1942 developed a unit nicknamed the “Mata-Hari” that recorded test-flight data on photosensitive paper, which sometimes survived a crash. The U.S. Army Air Forces experimented with recording math voice data on a magnetic wire.

As civil aviation developed in the years after World War II, “crash-survivable” flight recorders came to be seen as a valuable tool in analyzing aviation disasters and contributing to the design of safer aircraft. However, truly serviceable flight recorders that had any chance of surviving plane crashes were not produced until several years after the war. A series of disastrous crashes of De Havilland Comet jetliners in 1953–54 spurred David Warren, a scientist at Australia’s Aeronautical Research Laboratory (ARL), to design the first combined FDR and CVR. The recording medium for Warren’s ARL Flight Memory Unit was steel wire of the type then being used in magnetic audio recorders. Warren’s invention became the basis for subsequent flight recorders. Although Warren’s recorder, as produced commercially by S. Davall & Son beginning in 1960, was housed in an egg-shaped casing that was painted red, the term black box, which arose during World War II as slang for sensitive aircraft components that were encased in black metal boxes, was applied to the device.

Parallel developments occurred elsewhere in the world. In the United States, James J. Ryan, an engineer employed by General Mills, in 1953 developed the VGA Flight Recorder, which sensed changes in velocity (V), gravitational forces (G), and altitude (A) and inscribed the measurements on a slowly moving strip of aluminum foil. As released in 1953 and sold by General Mills to the Lockheed Aircraft Company, the entire apparatus was enclosed in a yellow-painted spherical shell. Numerous other devices were produced employing various recording media, from metal strips to, eventually, magnetic tape.

During the 1960s, crash-protected FDRs and CVRs became mandatory on airliners around the world. Most flight recorders employed magnetic tape, but during the 1990s a great advancement came with the advent of solid-state memory devices. Memory boards are more survivable than recording tape, and the data stored on them can be retrieved quickly by a computer carrying the proper software. A complete picture can be created of conditions on the aircraft during the recorded period, including a computer-animated diagram of the aircraft’s positions and movements. Verbal exchanges and math sounds retrieved from CVR data are transcribed into documents that are made available to investigators along with the actual recordings. The release of these materials to the public is strictly regulated.

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