scrambler
15th Dec 2007, 21:57
From todays age
http://www.theage.com.au/news/national/oops-and-downs-air-of-unreality-can-be-plane-scary/2007/12/15/1197568332270.html?page=fullpage#contentSwap1
Is this article designed to educate or scare the average punter. Perhaps they should have pointed out that by jettisoning the wings the problem is removed?
William Birnbauer
December 16, 2007
AS YOU prepare to fly off somewhere for Christmas, consider this: there is a chance your pilot once thought he was perched on the wing of his plane watching himself fly it.
Or, as happens more commonly, he may have believed the plane was pitching up or down when it was level or thought it was going straight when it was turning. He may have experienced what aviation doctors call the "knife edge" and "giant hand" illusions.
In the first, pilots sense that their aircraft is positioned precariously in space and extremely sensitive to the controls. The giant hand illusion is the opposite: pilots feel the plane is immovable in the air and unresponsive to controls — that a giant hand is holding it aloft.
These are some of the more bizarre manifestations of a potentially dangerous phenomenon known as spatial disorientation, which the United States Federal Aviation Administration says is the inability to tell which way is up.
In 1999 spatial disorientation (SD) was blamed for the plane crash in which John F. Kennedy jnr and his wife died in a night flight over water near Martha's Vineyard, in Massachusetts.
Almost every career pilot will experience some form of the phenomenon, says an aviation medicine expert, David Newman, who recently completed a study of SD and its role in accidents for the Australian Transport Safety Bureau.
"If a pilot flies long enough as a career, or even a hobby, there is almost no chance that he or she will escape experiencing at least one episode of SD," he says. "Looked at another way, pilots can be considered to be in one of two groups: those who have been disorientated, and those who will be."
International studies show that spatial disorientation was responsible for between 6% and 32% of major aviation accidents, and between 15% and 26% of fatal accidents.
A report by the former Australian Bureau of Air Safety Investigation, which examined night take-off accidents between 1979 and 1993, found that of the 35 accidents recorded, 15 involved spatial disorientation as a primary factor.
Ray Cronin, one of Australia's most experienced pilots and instructors, is only too aware of the risks. He estimates he has experienced SD half a dozen times over more than three decades in the industry. He says that when visual references disappear, such as occurs in cloud or at night, inexperienced pilots have only 20 seconds before losing control.
Mr Cronin, who owns Kestrel Aviation, said that without visual references pilots may not believe they were flying on their sides or were in a spiral dive — despite what their instruments showed.
"That's when you have this mental conflict and you break out into a sweat," he said. "It's the ultimate discipline. You've got to pull yourself together, and say the information in front of me is reliable."
Dr Newman told The Sunday Age that although less likely than with pilots, passengers could also experience SD, but they were usually preoccupied with meals or entertainment. Passengers may feel they are going straight when they are actually turning.
So why does SD occur? Dr Newman explains that humans normally can accurately determine which way is up thanks to three sensory systems most of us take for granted: sight, the balance organs of the inner ear (vestibular system) and what are colloquially known as "seat-of-the-pants" sensors.
These combine to feed information to the brain. With these we determine our position within fixed horizontal (the Earth's surface), and vertical (the force of gravity) co-ordinates. The visual system provides about 80% of the raw orientation data so that when it is dark, or the weather is bad, pilots rely on the remaining 20%, split evenly between vestibular and "seat-of-the-pants" sensors. The latter is a pressure sensor in our joints, tendons, ligaments, muscles and skin that tells the brain that we are upright.
The problem, says Dr Newman, is that these two complex systems are prone to illusions and misinterpretation. And none was designed to work in the air. Dr Newman's report describes numerous illusions that the industry has given descriptive terms, such as the graveyard spin, the leans, and the dark-night take-off or pitch-up.
Rare illusions such as the pilot watching himself flying from the wing-tip were associated with feelings of unreality and detachment.
"While seemingly bizarre, these illusions are generally associated with high-altitude flight, where the pilot has a relatively low-level workload. Under such fish-bowl conditions, the brain can wander and generate these strange illusions." While well recognised in aviation, most people were not aware of the condition, and that's not a bad thing, according to Dr Newman.
"Do we want passengers worrying that the pilots are going to get an illusion? I mean, people wouldn't fly if they thought it was going to happen," he said. "It's really the same style of problem as hypoxia, a lack of oxygen, which is just a function of going flying. We know how to deal with it."
Dr Newman said the prevalence of SD was underestimated. Pilots often were reluctant to report it in case they lose their licence. When pilots died in plane crashes, it was difficult to positively blame SD.
Lost in space
■Spatial disorientation happens when a pilot loses a sense of up and down, or is unable to correctly interpret aircraft attitude, altitude or airspeed.
■It usually happens when flying into bad weather. Low or no visibility may block out external visual horizon.
■When the pilot cannot see a horizon there is a "drift in the inner ear", which, if left uncorrected, can lead to the pilot turning the plane without realising it.
■Mistakes in the turn about any axis can build at a rate of 0.2 to 0.3 degrees per second.
■If the pilot is not trained to use gyroscopic flight instruments, these errors build to a point where the plane enters a steep diving turn known as a graveyard spiral.
■During the time leading up to and well into the manoeuvre, the pilot is not aware that he is turning, convinced all along that he is flying straight.
http://www.theage.com.au/news/national/oops-and-downs-air-of-unreality-can-be-plane-scary/2007/12/15/1197568332270.html?page=fullpage#contentSwap1
Is this article designed to educate or scare the average punter. Perhaps they should have pointed out that by jettisoning the wings the problem is removed?
William Birnbauer
December 16, 2007
AS YOU prepare to fly off somewhere for Christmas, consider this: there is a chance your pilot once thought he was perched on the wing of his plane watching himself fly it.
Or, as happens more commonly, he may have believed the plane was pitching up or down when it was level or thought it was going straight when it was turning. He may have experienced what aviation doctors call the "knife edge" and "giant hand" illusions.
In the first, pilots sense that their aircraft is positioned precariously in space and extremely sensitive to the controls. The giant hand illusion is the opposite: pilots feel the plane is immovable in the air and unresponsive to controls — that a giant hand is holding it aloft.
These are some of the more bizarre manifestations of a potentially dangerous phenomenon known as spatial disorientation, which the United States Federal Aviation Administration says is the inability to tell which way is up.
In 1999 spatial disorientation (SD) was blamed for the plane crash in which John F. Kennedy jnr and his wife died in a night flight over water near Martha's Vineyard, in Massachusetts.
Almost every career pilot will experience some form of the phenomenon, says an aviation medicine expert, David Newman, who recently completed a study of SD and its role in accidents for the Australian Transport Safety Bureau.
"If a pilot flies long enough as a career, or even a hobby, there is almost no chance that he or she will escape experiencing at least one episode of SD," he says. "Looked at another way, pilots can be considered to be in one of two groups: those who have been disorientated, and those who will be."
International studies show that spatial disorientation was responsible for between 6% and 32% of major aviation accidents, and between 15% and 26% of fatal accidents.
A report by the former Australian Bureau of Air Safety Investigation, which examined night take-off accidents between 1979 and 1993, found that of the 35 accidents recorded, 15 involved spatial disorientation as a primary factor.
Ray Cronin, one of Australia's most experienced pilots and instructors, is only too aware of the risks. He estimates he has experienced SD half a dozen times over more than three decades in the industry. He says that when visual references disappear, such as occurs in cloud or at night, inexperienced pilots have only 20 seconds before losing control.
Mr Cronin, who owns Kestrel Aviation, said that without visual references pilots may not believe they were flying on their sides or were in a spiral dive — despite what their instruments showed.
"That's when you have this mental conflict and you break out into a sweat," he said. "It's the ultimate discipline. You've got to pull yourself together, and say the information in front of me is reliable."
Dr Newman told The Sunday Age that although less likely than with pilots, passengers could also experience SD, but they were usually preoccupied with meals or entertainment. Passengers may feel they are going straight when they are actually turning.
So why does SD occur? Dr Newman explains that humans normally can accurately determine which way is up thanks to three sensory systems most of us take for granted: sight, the balance organs of the inner ear (vestibular system) and what are colloquially known as "seat-of-the-pants" sensors.
These combine to feed information to the brain. With these we determine our position within fixed horizontal (the Earth's surface), and vertical (the force of gravity) co-ordinates. The visual system provides about 80% of the raw orientation data so that when it is dark, or the weather is bad, pilots rely on the remaining 20%, split evenly between vestibular and "seat-of-the-pants" sensors. The latter is a pressure sensor in our joints, tendons, ligaments, muscles and skin that tells the brain that we are upright.
The problem, says Dr Newman, is that these two complex systems are prone to illusions and misinterpretation. And none was designed to work in the air. Dr Newman's report describes numerous illusions that the industry has given descriptive terms, such as the graveyard spin, the leans, and the dark-night take-off or pitch-up.
Rare illusions such as the pilot watching himself flying from the wing-tip were associated with feelings of unreality and detachment.
"While seemingly bizarre, these illusions are generally associated with high-altitude flight, where the pilot has a relatively low-level workload. Under such fish-bowl conditions, the brain can wander and generate these strange illusions." While well recognised in aviation, most people were not aware of the condition, and that's not a bad thing, according to Dr Newman.
"Do we want passengers worrying that the pilots are going to get an illusion? I mean, people wouldn't fly if they thought it was going to happen," he said. "It's really the same style of problem as hypoxia, a lack of oxygen, which is just a function of going flying. We know how to deal with it."
Dr Newman said the prevalence of SD was underestimated. Pilots often were reluctant to report it in case they lose their licence. When pilots died in plane crashes, it was difficult to positively blame SD.
Lost in space
■Spatial disorientation happens when a pilot loses a sense of up and down, or is unable to correctly interpret aircraft attitude, altitude or airspeed.
■It usually happens when flying into bad weather. Low or no visibility may block out external visual horizon.
■When the pilot cannot see a horizon there is a "drift in the inner ear", which, if left uncorrected, can lead to the pilot turning the plane without realising it.
■Mistakes in the turn about any axis can build at a rate of 0.2 to 0.3 degrees per second.
■If the pilot is not trained to use gyroscopic flight instruments, these errors build to a point where the plane enters a steep diving turn known as a graveyard spiral.
■During the time leading up to and well into the manoeuvre, the pilot is not aware that he is turning, convinced all along that he is flying straight.