Aerospace Physiology JP101-JP112 Flashcards
Human factors - JP101
study of the physiological, physical, psychological, and pathological limitations and capabilities of people as they interact with their environment
atmosphere
the gaseous envelope surrounding the Earth
Atmospheric Functions
It contains oxygen, essential for animal life and carbon dioxide, essential for plant life. It is a shield that attenuates cosmic and ultraviolet radiation.
Precipitation occurs in the atmosphere, helping maintain the temperature and climate.
Atmospheric Composition
The gaseous envelope surrounding the Earth contains nitrogen, oxygen and argon with traces of carbon dioxide and inert gases (such as helium and neon).
Atmospheric Gas Percentages
The approximate percentages of gases in the atmosphere are 78 percent nitrogen, 21 percent oxygen and 1 percent other gases (including 0.03 percent carbon dioxide).
Pressure
Force/Area
Units of measurement for pressure
psi, mmHg, inHg
Atmospheric or barometric pressure
the combined weight of all the atmospheric gases acting to create a force upon the surface of the Earth.
standard temperature lapse rate
altitudes up to about 35,000 feet reflect a constant decrease in temperature of about 2 deg C (3.6 deg F) per 1,000 feet
physiological zone
extends from sea level to approximately 10,000 feet and is the zone the human body is adapted to
altitude when the use of supplemental oxygen is required
When flying unpressurized above 10,000 feet MSL
Physiological Deficient Zone
This zone extends from approximately 10,000 feet to approximately 50,000 feet. Because of reduced atmospheric pressure, inadequate oxygen is available to sustain normal physiologic functions. Also, decompression sickness (caused by evolved gas) can occur in the body tissues and joints.
Altitude required for pressure suits
FL500
Space Equivalent Zone
exists above 50,000 feet. The physiological problems of flight above 50,000 feet are essentially the same as those for space. The need for protection in a sealed cabin or pressure suit, the problem of ebullism (tissue water vaporization) above 63,000 feet
mmHg in each zone
760 at 0 MSL, 523 at 10,000 MSL, 87 at 50,000 MSL
Partial Pressure
the amount of pressure that a single gas out of a mixture of gases contributes to the sum or total pressure of that mixture, designated with a P in front of the element/compound symbol
Dalton’s Law
explains how exposure to a high ambient altitude can reduce the available oxygen. As ambient altitude increases, the partial pressure of oxygen (PO2) decreases even though the percentage of oxygen remains the same.
Boyle’s Law
When the temperature remains constant, as in the human body, a volume of gas is inversely proportional to the pressure surrounding it.
Henry’s Law
the amount of gas in a solution varies directly with the partial pressure of that gas over the solution.
The Law of Gaseous Diffusion
A gas will diffuse from an area of higher concentration or pressure to an area of lower concentration or pressure until equilibrium is reached.
Charles’ Law
When volume is constant, the pressure of a gas increases or decreases proportionally to an increase or decrease in its temperature.
Respiration - JP102
the process our body uses to exchange gases with our environment. The primary purpose of respiration is to provide oxygen to, and remove excess carbon dioxide from, the body. The respiratory process also helps maintain the acid-base balance (pH) of the blood.
Metabolism
the sum of all the physical and chemical processes used by cells to produce energy and building materials needed to sustain life.
Phases of Respiration
ventilation, diffusion, transportation and utilization
Ventilation
The volume of gas exchanged between the lungs and the ambient environment per unit time.
Diffusion
Oxygen and carbon dioxide pass through the alveolar membrane and capillary walls.
Transportation
Links the transfer of gases from the lungs to their site of production or use in the cells of the body.
Utilization
Cellular metabolism. This phase involves the use of oxygen in energy production and the production of carbon dioxide and water
The Oral-Nasal Cavities (mouth, pharynx, etc.)
Lined with a mucous membrane. Hair like structures (cilia) in the nasal cavity mucous membrane filter inspired air. The oral cavity plays a lesser role in filtering the air, but regardless of the pathway, air is humidified and heated to body temperature before entering the lungs.
Trachea (or windpipe)
Divides into two branches, one each to the left and right lung. These branches (bronchi) form part of the root structures of the lungs’ air passages.
Lungs
Occupy the greatest part of the chest or thoracic cavity and connect to the bronchi. The lungs’ prime function is to allow oxygen to move from the air to the microscopic blood vessels (capillaries) and carbon dioxide to move from the capillaries into the lungs.
Alveoli
Tiny air sacs in the lungs. Their walls have an excellent blood supply provided by capillaries. In the lung, gas exchange between the respiratory and circulatory systems occurs at the alveolar-capillary interface.
Composition of Inspired Air
Excluding trace amounts of other gases, air is composed of nitrogen and oxygen.
The Dynamic Nature of the Lungs
In adults, the tidal volume (the amount of gas inspired or expired with each normal breath) is about 500 milliliters. This air is normally exchanged an average of 12 to 16 times per minute.
Active/Passive component of respiration
inspiration/exhalation
PCO2, PO2, and pH
Normal ventilation is controlled subconsciously and adapts to changes in ________.
Response to PCO2
The most important factor in the control of ventilation under normal conditions is the PCO2 of the arterial blood.
Response to PO2
Arterial PO2 can normally be reduced from the normal 100 mm Hg to 50–60 mm Hg without evoking a ventilatory response, showing that the role of this hypoxic (low oxygen) stimulus in the day by day control of ventilation is small.
Response to pH
A reduction in arterial blood pH increases ventilation. It is difficult to separate the ventilatory response caused by a fall in pH from that caused by an accompanying increase in PCO2
circulatory system
transports and distributes nutrients and oxygen to the tissues and removes waste products of metabolism
The Heart
Consists of four chambers, but functions as two pumps in series — one to propel blood through the lungs, exchanging O2 and CO2 (the pulmonary circulation) and one to drive blood to all other tissues of the body (systemic circulation)
The Blood
Circulating through the cardiovascular system is a mixture of cells within a liquid called plasma. The cells of the blood serve multiple functions essential for metabolism and defense of the body.
Red Blood Cells
The primary purpose of the red blood cell (RBC) is to transport O2 and CO2
Hemoglobin
Main function is to transport oxygen
hypoxia
A lack of oxygen in body tissues that is sufficient to cause an impairment of function
hypoxic hypoxia
An increase in altitude will reduce the PO2 of inspired air causing ________.
stagnant hypoxia
Blood pooling in the lower extremities during increased-g maneuvering can cause _______, another factor that can reduce oxygen delivery to tissues.
hypemic hypoxia
Various types of toxic gases can cause the blood to carry less oxygen
histotoxic hypoxia
Various types of toxic gases can cause the tissues to be unable to take up or use oxygen
Hypoxia JP103
is an oxygen (O2) deficiency sufficient to cause impairment of function. It occurs most frequently when protection against the fall in O2 partial pressure at altitude fails.
altitude hypoxia
Threshold usually around 10,000 ft MSL, Hypoxic hypoxia is usually caused by exposure to low barometric pressure and is frequently referred to as _____.
Stagnant Hypoxia
Occurs when reduction in cardiac output, pooling of the blood, or restriction of blood flow reduces O2 delivery frequently caused by either hyperventilation or acceleration (G forces)
Histotoxic Hypoxia (2)
Results when the O2 delivered to the cells cannot be used for energy production. Adequate O2 is available to the lungs and the blood is capable of carrying it to the tissues. However, the tissues and cells are unable to use the available O2. Caused by presence of cyanide.
Factors Influencing Hypoxia
Altitude, rate of pressure change, duration of exposure, individual tolerance, physical activity, self-imposed stress,
Signs of hypoxia
increase in rate and or depth of breathing, cyanosis (blueness of the skin, because of insufficient oxygenation of the blood), mental confusion, poor judgment, loss of muscle coordination, and unconsciousness. Behavioral changes, such as euphoria (an exceptional feeling of well-being) or belligerence
Symptoms of hypoxia
dizziness, fatigue, hot and cold flashes, blurred vision, tunnel vision, tingling and numbness. Euphoria and belligerence may also be experienced. headache, nausea, a feeling of apprehension and air hunger
Time of Useful Consciousness (TUC)
The period of time from the interruption of the oxygen supply or exposure to an oxygen poor environment, to the time when useful function is lost. You are no longer capable of taking proper corrective and protective action, but are still conscious. It is not the time to total unconsciousness.
Ways to treat Hypoxia
- Maximum Oxygen Under Pressure (all 3 switches in on position for O2), 2. Connections - Check Security, 3. Breathe at a Rate and Depth Slightly Less Than Normal Until Symptoms Disappear, 4. Descend Below 10,000 Feet and Land as Soon as Possible,
Pressure Breathing
Delivers oxygen, under pressure, through the crewmember’s oxygen mask. It is a method of maintaining adequate PO2 in the lungs at cabin altitudes above 40,000 ft.
Hyperventilation
a condition in which the rate and or depth of breathing is abnormally increased. This increase causes an excessive loss of carbon dioxide (CO2) from the blood. The excessive loss of CO2 changes the acid-base balance of the blood making it more alkaline.
Causes of Hyperventilation - Voluntary
can be voluntarily induced or corrected by consciously increasing or decreasing the rate and depth of breathing.
Causes of Hyperventilation - Involuntary
Fear, apprehension, tension or stress will sometimes cause an individual to subconsciously increase their rate and or depth of breathing. These stress factors are the most frequent causes of hyperventilation. However, positive pressure breathing can also contribute to hyperventilation.
Recognition of Hyperventilation - Signs
Most often observed in hyperventilation are increased rate and depth of breathing, muscle tightness and twitching, paleness, cold clammy skin, muscle spasms, rigidity and unconsciousness.
Recognition of Hyperventilation - Symptoms
Most often noted are dizziness, faintness, slight nausea, numbness, tingling or coolness and muscle tremors.
Prevention of Hyperventilation
control your rate and depth of breathing
Treatment of Hyperventilation
voluntary reduction in your rate and depth of breathing
Treatment of Hyperventilation (steps)
- Maximum oxygen under pressure, 2. Connections-Check Security, 3. Breathe at a Rate and Depth Slightly Less Than Normal Until Symptoms Disappear, 4. Descend Below 10,000 Feet MSL and Land as Soon as Possible
Trapped Gas disorder
When expanding gas cannot escape places such as the teeth, sinuses, middle ear, gastrointestinal (GI) tract
Ear Anatomy
external ear canal, ear drum, middle ear, inner ear, eustacian tubes, opening to thoat
Valsalva Manuever
Yawning, swallowing, tensing throat muscles, to relieve air pressure in the throat
Ear Block
if the pressure differential of the atmosphere over the middle ear exceeds 80 mmHg, it may be impossible to open the Eustachian tube with equalization pressure methods.
If you are suffering from upper respiratory infections or apparent allergic reactions…
you should not fly or participate in an altitude chamber flight
Delayed Ear Block (Post-Flight ear block)
Can occur up to 2 to 6 hours after landing. It results from breathing high percent oxygen for an extended period of time.
Sinuses
Sinuses are cavities in the bone of the skull and are lined with moist mucous membranes, consists of frontal sinuses, located above and behind each eye, and the maxillary sinuses, located in the bones of the cheeks beneath the eyes.
Sinus Block
When pressure changes occur during ascent or descent, the gases in the sinuses increase or decrease in volume, if the sinus ducts are swollen because of an upper respiratory infection, there may be a blockage of the ducts.
Expansion of Trapped GI Gas
A problem that may be experienced with a decrease in atmospheric pressure is discomfort from expansion of gases in the GI tract
decompression sickness
the disorder produced by the evolution of gas from tissues and fluids of the body (nitrogen bubble formation)
DCS - The Bends
The evolution of nitrogen bubbles into the joints of the body, causing pain. Once bends have developed, breathing 100 percent oxygen while at altitude will not normally resolve the pain. Descent is the only cure and is mandatory for any DCS.
DCS - Neurological Manifestations
In rare incidents of high altitude exposure, the brain and or spinal cord may be affected by nitrogen bubbles, common symptoms are very similar to those of a stroke: disturbances in vision, varying from blind spots in the visual field to flashing and or flickering lights. Other symptoms include severe persistent headache, partial paralysis, loss of speech or hearing, vertigo, distinct sudden personality changes or loss of orientation. Immediate descent is necessary after any evidence of Central Nervous System involvement.
DCS - Chokes
symptoms are very similar to those of a heart attack, and may be misdiagnosed if they are presented to a civilian physician. Immediate decent is necessary
DCS - Skin Manifestations
a mottled, reddish or purplish rash develops on the skin. The rash may be localized in a small area or may be diffused over the body. A slight swelling of the skin may be noted and a slight increase of temperature may exist.
Delayed Reactions (DCS)
Occasionally, the onset of DCS symptoms may appear after the flight. This condition is known as a delayed DCS and may occur within 12 hours.
Factors Affecting DCS Incidence and Severity
increased altitude, rate of ascent, Physical Activity, Previous Injury, age, body composition, repeated exposure, dehydration, diving prior to flying,
USAF and USN regulations forbid flight within _____ after SCUBA diving
24 hours of a compressed air exposure
Prevention of DCS
Aircraft Pressurization, denitrogenation
Treatment of DCS
- 100 percent oxygen 2. descend ASAP 3. consult flight surgeon or aeromedical examiner
Pressurization (JP104)
mechanical means of maintaining greater than ambient pressure within an aircraft cabin.
isobaric system
constant cabin pressure
isobaric-differential system
the aircraft is unpressurized until a preset cabin pressure is reached. Once reached, the isobaric function of the system maintains a constant pressure within the cabin until a selected pressure differential (cabin pressure versus ambient pressure) is attained.
Advantages of Pressurization Systems
- Reduced probability of DCS, 2. Reduced possibility of hypoxia (primary purpose of aircraft pressurization is 1 and 2), 3. Reduced need for supplemental oxygen equipment below 10,000 feet cabin altitude. 4. Reduced expansion of gastrointestinal trapped gas, 5. Controls cabin temperature, humidity, and ventilation within a desired comfort range, 6. Allows the crew and passengers to move freely within large cabins unencumbered by oxygen equipment, 7. Minimizes fatigue and discomfort of crew and passengers during long flights (air evacuation, troop transport, etc.), 8. Protects the sinuses and middle ears from sudden pressure increases during descents by slowly scheduling the
cabin descent
Disadvantages of Pressurization Systems
- Decompression. The primary, and most critical, disadvantage of aircraft pressurization is the potential for decompression. 2. Increased aircraft weight because of the additional fuselage strength required. 3. Requires additional design engineering, mechanical systems, and engine power. 4. Decreased performance and payload. 5. Increased maintenance requirements and costs. 6. Requires control of cabin air contamination from smoke, fumes, carbon monoxide, carbon dioxide, water vapor
and odors
Types of Decompression
- Slow Decompression—Can occur when a leak develops from a failing pressure seal. 2. Rapid Decompression — Easily recognized and you must consider its physiological effects. 3.
Factors Affecting Decompression
speed - size of cabin or size of opening, initial difference determines rate and severity. Larger pressure differential leads to a more severe decompression. The pressure ratio, defined as the ratio between cabin pressure and ambient pressure, determines the time required for decompression.
Physical Indications of a Rapid Decompression
Explosive Noise, Windblast/Flying Debris, Fogging, Temperature, rapid pressure drop
Anatomy of the Eye (JP105)
Cornea, pupil, Lense, rods, Cones, Retina, optic disk, Fovea, optic nerve (anatomy from front to back)
The Retina
The retina is the innermost layer of tissue of the eye, containing millions of photoreceptors (rods and cones) allowing you to “see” an image.
Optic Disk
Since there are no photoreceptors at this site, it is effectively an anatomical blind spot. However, the optic disks are located in different locations in each eye
The Fovea
Next to each optic disk is the fovea, another area of the retina with a specialized function. It is a tiny pit containing only cones and the natural point on the retina where the lens focuses an image. This physiological blind spot will be discussed during night vision.
Photoreceptors - Cones
The photoreceptors allowing you to see the details of the world in color under bright light conditions. They are densest in the center of the retina and decrease in number toward the periphery.
Photoreceptors - Rods
Photoreceptors most dense at the periphery of the retina and decreasing in number as the center of the retina is approached. They allow you to see in gray tones under conditions of dim light and provide for our peripheral vision.
The Visual Field
The total visual field is about 160 to 170 deg, depending on the individual. Of this total, the central 3 deg is used for focal vision. The remaining visual field is used for peripheral vision.
Focal vision
Concentrated on the fovea, constituting 3° of the total visual field. Its primary function is to recognize and identify objects, generally to answer the “what is it” question.
Peripheral vision
Is used primarily to orient oneself relative to the environment and constitutes the remainder of the visual field. Unlike focal vision, it does not require active attention on your part to process information and serves to orient you to your environment. The majority of the photoreceptors used in peripheral vision are rods.
Physiological limitations
involve visual contrast of objects against their backgrounds, shapes of targets, movement of targets and environmental conditions.
Visual Contrast
helps the eye acquire the target. Objects are sensed by the differences between light and dark. Therefore, the greater the contrast of a target against its background, the easier it is to detect.
Shapes of Targets
Also affect the eyes’ ability to acquire them. The larger, more angular the shape of the target, the easier it is to see and is sometimes referred to as its “visual cross section.”
Movement of a Target
Against a background aids acquisition by the eye. A moving target is easier to detect than a stationary target. The degree of movement required also depends upon the background.
Environmental Conditions
Can enhance or hamper your vision. Obviously, cloudy conditions restrict visibility but clear conditions can also cause problems. Glare is a significant problem, especially at high altitudes.
Empty-Field Myopia
Caused by the tendency of the eyes to focus at approximately 3 meters in front of the face. This phenomena occurs if the eyes have nothing to focus on at infinity.
Midair Collision Avoidance
“see and avoid” principle is founded on the crewmembers’ ability to maintain visual separation from other aircraft.
Perception/Reaction Time
Determined by specific physiological and perceptual limitations of what you can see and react to in a given time
Visual Acquisition
Of another aircraft in a MAC situation also has physiological limitations. First, because of the geometry of a MAC, you lose motion as a cue to acquire the other aircraft with your peripheral vision. When a collision occurs, the other aircraft has little or no apparent motion on the windshield.
Scanning Technique
Maximum scanning effectiveness is achieved by a series of short, regularly-spaced eye fixations. A common scanning technique is to take an area of sky and divide it into sectors.
Visual illusions
a form of spatial disorientation; you mentally perceive an image different than the image seen by the eye.
Illusions - Physical Factors
The horizon is used by the peripheral visual field as a cue for orientation and balance. However, when a perceived horizon is not parallel to the earth’s surface, you may still believe it is the correct horizon. False horizons - hazy fog layer, slanted cloud level. Rising/sloping terrain at the front of a runway coming in on glideslope
Illusions - Perceptual Factors
The processing and perception of visual information by the brain is affected by a variety of variables. These variables include experience and expectancy, fatigue and other self-imposed stresses. Another example, different runway that is wider, you may flare earlier
Laser Awareness
Lasers can be very dangerous to aircrew members, typically at low altitudes. High Energy lasers are capable of destroying material, but low energy lasers can blind eyes and sensors.
Laser Basics
The word “Laser” is an acronym for Light Amplification by the Stimulated Emission of Radiation. Just as there unique terms in the kinetic weapons environment, there are unique terms in the laser world.
Lasers - Coherency and Collimation
Because the laser beam stays together, it passes through space very efficiently in a collimated beam. Collimation or directionality refers to how straight the beam propagates without spreading.
Lasers - Monochromatic
Generally, lasers are a single color; one wavelength or a very narrow band. The wavelength that a laser emits is a key factor in analyzing the hazards and physical properties of the laser.
Lasers - Hazards
Lasers can be hundreds of times “brighter” than the sun, and high intensity can be projected over long distances. Also, light can be sharply focused by the eye.
Lasers - Procedures after Exposure
Location of the source, Appearance, Scanning or tracking, Effects, Regularity
Physiology of Night Vision (JP106)
Relies heavily on the rods to see in low light. The rods’ ability to function in low-light environments is high but their adaptability to low-light levels is fairly slow. Rods are very sensitive to oxygen in the blood.
The Night Blind Spot
is a second blind spot in the eyes, since the cones in the fovea require high light levels to function.
Perceptual Errors (night) - False Horizons
At night can be caused by any series of lights in a linear formation. The best preventive measure to decrease or eliminate the problem of false horizons is to ensure a good instrument cross-check.
Perceptual Errors (night) - Lack of Horizon
If you are flying at night over featureless unpopulated terrain or the ocean, you may not see a visible horizon. This environment can cause you to use a false horizon (if one becomes available) or rely on your vestibular system
Perceptual Errors (night) - The Black Hole Effect
Caused by a lack of a visual horizon for the peripheral visual field to key on and use to orient the aircrew. It occurs most often during night visual approaches to airfields without surrounding city lights, or with a fairly small concentration of lights behind the runway.
Perceptual Errors (night) - Autokinesis
Means “self-motion.” This illusion occurs by staring at a single light source against a dark background. Autokinesis can occur by fixating on a star, stationary ground lights at night, or lights from other aircraft. After staring at the light for a few moments, it appears to move randomly.
Perceptual Errors (night) - Weather Factors
Nighttime visual illusions can be caused by the same types of weather that cause daytime visual illusions.
Perceptual Errors (night) - Haze and Ground Fog
Tend to decrease your forward and slant range visibility just as they do during the daytime.
Perceptual Errors (night) - Rain and Snow
Can cause light from aircraft landing lights to be reflected back into the cockpit. As a result, you may sense an overwhelming visual sensation of the aircraft pitching up or down.
Situational awareness (JP107)
a continuous perception of self and aircraft in relation to the dynamic environment of flight, threats, and mission, and the ability to forecast, then execute, tasks based on that perception.
Levels of Awareness
conscious part of our minds is considered a serial processor. This is the level at which we actively process information and we are at our best when we do one thing at a time. subconscious part of our minds is considered a parallel processor. This level is capable of doing more than one thing at a time and doing it very quickly.
Causes of LSA - Attention Threats
LSA - Loss of situational awareness, Attention threats hamper or prevent proper situational awareness. They can occur when the conscious level of awareness is distracted, has too many tasks to manage, or fails to monitor the environment.
Temporal Distortion (LSA)
This is a misperception of how much time has passed. This is a natural characteristic of the human brain, especially in response to high workload or stressful situations.
Channelized Attention (LSA)
Channelized attention is the focusing of conscious attention on a limited number of environmental cues to the exclusion of others of higher or more immediate priority. Channelized attention as the number one human performance factor causing a loss of situational awareness.
Task Saturation (LSA)
Task saturation occurs when there is too much to attend to at one time. You can end up missing important cues.
Distraction (LSA)
The interruption of conscious attention to a task by a non-task-related cue is called a distraction.
Habituation (LSA)
the adaption and subsequent inattention to a cue. Habituation can occur when there’s a high workload, poor aircraft design, or lack of recent experience resulting in misprioritization of cues.
Negative transfer (LSA)
due to something learned so well that it’s performed at a subconscious level.
Inattention
Inattention occurs when you are under challenged.
Inappropriate Motivation
occurs when your personal motivation is not consistent with the goals of your mission and can be exhibited in several ways.
Pressing
Placing unnecessary demands on yourself to complete a mission, or pushing equipment beyond known limitations
Misdirected Peer Pressure
Attempting prohibited maneuvers because of a dare or disregarding regulations to impress your friends are all deadly examples of misdirected peer pressure.
Supervisory Pressure
However, situations will arise where you may feel intimidated by a supervisor, resulting in an unsafe situation.
Get-Home-Itis
the personal motivation to reach your destination that conflicts with safe completion of the mission.
Tools for Preventing LSA
IMSAFE - Illness, medication, sleep, alcohol, fatigue, eating. Also pre/post flight briefings asking “what if” questions
Cues for Recognizing LSA
Fixation, ambiguity, complacency, feel good, gut feeling/confusion, poor communication or slow to respond, failure to meet targets, improper procedures, unresolved discrepancies, no on flying the aircraft
Techniques for Recovering from LSA
Prioritize Tasks (1. Terrain Clearance tasks, 2. mission critical tasks, 3. Noncritical tasks), Communicate, Declare emergency
Spatial disorientation - JP108
the inability to accurately orient yourself with respect to the earth’s horizon.
Classifications of Spacial Disorientation
Unrecognized Spatial Disorientation (Type I)—Is the most dangerous type of SDO you can experience. Recognized Spatial Disorientation (Type II) — Is the least dangerous type of SDO. Incapacitating Spatial Disorientation (Type III) — Occurs when you are so disoriented that you are incapable of recovering even if it is recognized.
Orientation Sensory Systems - Visual
The eyes provide the strongest and, usually, the most reliable orientation information during flight. Recall from the Vision lesson, peripheral vision is the primary means the visual system uses to collect orientation cues. The orientation cues provided by the eyes are strong enough to overpower all other orientation system inputs
Orientation Sensory Systems - Vestibular system
The vestibular system is located in the inner ear and consists of two subsystems — the semicircular canals and the otolith organs. If flight instruments are not used when visual horizon inputs are lost due to flying in clouds, at night or in haze, the brain reverts to the vestibular system for orientation information.
The Semicircular Canals
Located in each inner ear. There are three canals in each ear, oriented at right angles to one another in the pitch (vertical), roll (lateral), and yaw (horizontal) axes. They measure angular acceleration caused when the head is turned or tilted.
Endolymph
Fluid that is stimulated into motion when the head accelerates in the axis of the canal. When the head is accelerated, the fluid in the canal lags behind because of inertia. This motion causes a concentration of specialized nerve cells called the cupula to bend in the direction of the fluid motion.
The Otolith Organs
Located near the base of the semicircular canals in the vestibular apparatus and sense linear acceleration. They consist of a base of nerve cells with hair like appendages that are embedded in a gelatinous substance containing calcium carbonate crystals.
Orientation Sensory Systems - The Somatosensory System
The somatosensory system consists of tactile pressure receptors in the skin, muscles, tendons and joints. The pressure receptors are used to help maintain posture and balance. The somatosensory system is often called the “seat-of-the- pants” sense.
Orientation Sensory Systems - The Auditory System
The auditory system can help maintain situational awareness and spatial orientation through feedback. This feedback is related to aircraft speed and its relationship to the noise produced by the aerodynamic forces acting upon the aircraft.
Somatogyral Illusions
Somatogyral illusions are caused by the stimulation of the semicircular canals due to angular acceleration. In this illusion, after you return to straight-and-level flight, you sense the aircraft is turning or banking in the opposite direction.
Somatogyral Illusions - The Leans
The most common vestibular illusion experienced in-flight. It is caused when the semicircular canal responsible for sensing acceleration in the roll axis is stimulated.
Somatogyral Illusions - The Graveyard Spin/Spiral
When the fluid is stabalized and the aircraft is in a spin and you do not perceive you are in a spin. Once you do come out of it, you perceive that you are spinning the opposite direction and then attempt to remove yourself from an opposite direction spin that actually isn’t happening.
Somatogyral Illusions - The Coriolis Illusion
Moving your head abruptly in a turn and you perceive a change in aircraft attitude
Somatogyral Illusions - The Giant-Hand Phenomenon
occurs when the vestibular stimulus is so strong that you cannot physically overcome the sensation of an opposite bank or roll. As a result, you reflexively roll the aircraft back to the original bank angle to defeat the sensation of opposite bank and cannot maintain a wings-level attitude.
Somatogravic Illusions
illusions that are caused by linear accelerations. The otolith organs respond to linear acceleration forces and the illusions usually involve the sensation of pitching up or down.
Somatogravic Illusions - Pitch Up/Down
The illusion or sensation of pitching up or down when exposed to a linear acceleration.
Somatogravic Illusions - The G-Excess Effect
Occurs when the aircraft is in a turn and you are looking outside the aircraft with your head up, towards the inside of the turn, or head-down looking towards the outside of the turn. The otolith organs respond to both the tilt of the head and the G force caused by the turn.
Vestibulo-Ocular Illusions
Vestibulo-ocular (ocular — the eye) illusions are the result of the eye’s reaction to either semicircular canal stimulation (oculogyral illusion) or otolith organ stimulation (oculogravic or elevator illusion). For example, when you turn your head, your eyes lag behind the motion and then make a quick compensatory motion to catch up (nystagmus).
The Oculogyral Illusion
Occurs when the semicircular canal in the yaw plane is stimulated. When the acceleration stops, the eyes continue to “flick” back and forth because of nystagmus. As a result of the nystagmus, objects far away appear to move.
Environmental Factors Affecting Spatial Disorientation
Weather, type of mission (night, formation, low level, refueling etc), time of mission/mission duration,
Physiological Factors Affecting SDO
Alcohol, self medication, dehydration, fatigue,
Other Factors Affecting SDO
Experience in IMC, mission preparation, recency of experience
Preventing SDO (5 ways)
Understand Limitations, remedy correctable factors, use capabilities properly, recognize high risk situations, stay alert
Overcoming SDO (7 Steps)
Transition to Instruments, believe the instruments, Back-Up the Pilot Flying on Instruments, Minimize Head Movements, Fly Straight and Level, Be Prepared to Transfer/ Assume Control, Egress
Motion Sickness Symptoms
The symptoms of motion sickness are nausea, sweating, belching, cold and clammy feeling, and headache. In some cases, active vomiting occurs and sometimes prostration (inability to remain standing).
Motion Sickness Prevention
Motion sickness decreases if good outside visual references exist. However, these references are not always available, but there are other tools you can use to help prevent motion sickness. One of the most important tools available to prevent motion sickness is your ability to eliminate or minimize self- imposed stress. You should be well hydrated before flight and continue to drink water during the flight.
Treatment
Acquiring a good outside visual reference will usually remove the symptoms. Sometimes, cool air blowing across the body decreases the symptoms and breathing 100 percent oxygen also helps. If the symptoms persist, you can employ a technique known as diaphragmatic breathing to help the symptoms subside. Inhale deeply through your nose, pause, exhale out your mouth, pause, and repeat the cycle until the symptoms subside.
Noise - JP 110
Noise is unwanted sound. The characteristics of noise of concern to you are frequency and intensity of the noise, duration of exposure to the noise, and distance from the noise source.
Frequency (pitch)
Sound waves are created by the alternate compression and rarification of air, above and below atmospheric pressure respectively. The number of times each second that these oscillations occur is referred to as the frequency.
Broad vs Narrow Band
Variety of noises vs monotone/single frequency noise
Intensity (noise)
Or loudness is the magnitude of an acoustic event and is a measure of pressure of sound waves in the ear canal.
Sound units of measure
frequency measured by one oscillation per second is termed one Hertz (Hz), intensity measured by the decibel (dB), is used to measure these pressures. The decibel is a logarithmic expression of the ratio of the sound pressure being measured to the lowest sound pressure detectable by the normal human ear at 1,000 Hz. Duration - both time and intensity in DB
Human hearing limitations
The intensity threshold at which humans are susceptible to permanent hearing loss is 85 dB. The threshold for pain is 130 dB and physical damage occurs at noise levels of 150 dB and above.
Duration (noise)
The length of exposure to noise plays a fundamental role in determining how much irreversible damage is inflicted on your hearing.
Conductive Hearing Loss
Occurs when one of the parts of the ear that is designed to transmit mechanical energy fails. For instance, a ruptured eardrum cannot transmit the sound energy to the ossicles of the middle ear.
Sensorineural Hearing Loss
Occurs when the hair cells of the cochlea are damaged, destroyed, or degenerated due to overexposure to noise.
Temporary vs Permanent Threshold Loss
A nonpermanent loss of hearing in a frequency or range of frequencies after exposure to loud noise (temporary). Permanent - Occurs when the cochlea’s ability to convert a certain frequency or frequencies to electrical signals is lost because of hair cell damage.
Non-Auditory Effects of Noise
On crewmembers can pose problems in the flying environment. Excessive noise masks sound entering the ear and can make speech unintelligible. Masking of other crewmember’s speech can lead to misinterpretation of communication and cause the crew to make a mistake. Noise can increase stress, fatigue, sleep loss, irritablility, distraction, and uncooperativeness.
Devices to Protect from Hazardous Noise
Earplugs, Ear Defenders, Headsets and Flight Helmets, Combination of Protective Devices (protect up to 28-32 dB), Limiting Exposure (stay away from loud noise especially if you have an inherently loud aircraft)
Vibration
Vibration is defined as the rapid movement of an object in a back and forth motion. Vibration is described with the same parameters as sound — frequency, intensity and duration.
Vibration Frequency ranges
Vibrations occur throughout the frequency spectrum; however, vibration of very low frequency and high intensity are of most concern.
Vibration - Effects on Performance
Low altitude, high speed flight in weather causes the most severe vibration exposures. Vibration can affect your ability to perform at peak levels.
Vibration - Tracking
Horizontal tracking is generally not affected by vibration. However, vertical tracking is significantly impaired with vibration.
Vibration - Reaction Time
udies indicate that vibration does not typically influence crewmember reaction time to tasks executed at the conscious level. Deterioriates at the subconcious level.
Vibration - Visual Impairment
Vibration can cause blurred vision and therefore reduce your visual efficiency.
Vibration - Fatigue
Vibration contributes to fatigue, a prime factor in decreased crewmember performance.
Symptoms of Exposure to Vibration
Symptoms which may result from exposure to harmful vibration frequencies are loss of appetite, complacency, perspiration, salivation, nausea, headache and vomiting. Severe vibration can also result in fatigue, discomfort, and actual pain.
Physical principles of G Forces JP111
Speed, Velocity, Acceleration
3 types of G forces
transverse G, negative G, and positive G.
Transverse G Force
The force applied to the front (+Gx) or back (-Gx) of the body. +Gx and -Gx forces are normally encountered during takeoffs, acceleration in level flight, and landing.
Negative G Force
Defined as the force being applied from the feet towards the head and is expressed as -Gz. Negative G force is not tolerated well by humans and is seldom experienced in high levels during normal flight. The physical symptoms of -Gz are a sense of weightlessness, congestion in the head and face, headache and visual blurring, redout.
Positive G Force
A force applied from the head towards the feet. It is expressed as +Gz. It occurs during turns and dive recoveries and is the G force most often experienced by crewmembers. Feeling of extreme increased weight and difficulty breathing
Factors Determining the Effects of G Forces
Magnitude of the G Force, Duration of Exposure to the G Force, Rate of Application (G onset), Direction of Force, Previous G Exposure
Physiological Effects and Symptoms of G Forces
Restricted Mobility, Cardiovascular Reflex (Each +Gz drops blood pressure 22 mm Hg), Vestibular (stimuli from fluid in ear is disrupted), Visual (retina starts to lose blood supply hence blackouts)
Blackout
As the G force increases, the blood pressure drops to where it cannot overcome the intraocular pressure and all vision is lost. It is important to note that blackout does not mean you are unconscious. However, you are in imminent danger of G-LOC.
G-LOC
The brain has a 4 to 5 second oxygen reserve. Once blood flow ceases and the oxygen reserve is used, unconsciousness ______ results. Two types: absolute and relative.
Absolute Incapacitation - G-LOC
In absolute incapacitation you are actually unconscious for roughly 9 to 21 seconds, with an average time of 15 seconds.
Relative Incapacitation - G-LOC
Unfortunately, when you regain consciousness, you do not instantly return to an alert and functional state. You may experience mental confusion, disorientation, stupor, apathy, or memory loss. During this time, you are incapable of consciously flying the aircraft, making decisions, taking action against a threat, or communicating effectively. The time of relative incapacitation usually mirrors that of the absolute incapacitation.
Protection methods against G-LOC
Anti G suit, Anti G Straining maneuver
How to AGSM
muscle tensing (prevents blood pooling) and cyclic breathing (fights the closed glottis)
Common Errors of Performance (AGSM)
Most common cause of G-LOC is improper AGSM. Timing - The primary timing error is starting the AGSM after the onset of the G force. Loss of SA. Allowing air to leak from the throat, holding the breath in the mouth instead of catching it in the back of the throat, and insufficient muscle strain are additional errors in performing the AGSM. Allowing air to leak past the glottis causes the pressure in the chest to drop. Also insufficient muscle strain
Tolerance of Positive G forces
Physiological Factors (Physical, anerobic, and aerobic conditioning), Self imposed stress (Dehydration, Fatigue and sleep, drugs and self-medication, alcohol/hangover, hypoglycemia and missed meals)
Use of Over-The-Counter (OTC) Drugs JP112
In the civilian world, a person who catches a cold, comes down with the flu or physically feels bad, can take one of the many OTC drugs available. Crewmembers, however, are prohibited from self-medicating.
Effects of OTC Drugs
Primary Effect — Of each type of drug is the desired (intended) effect of the drug on the individual. Side Effects — Those effects known to accompany a drug but are additional to its desired effect. Synergistic Effects — Occur when the primary or side effect of a drug is modified in function or intensity when taken in combination with another drug. Idiosyncratic Effects — Those effects on an individual that are unusual and unexpected.
Types of OTC Drugs
Decongestants, Antihistamines, Vasoconstrictors, Pain Killers (Analgesics), Diet Pills
Adverse Effects - Decongestants
Shakiness, increased heart rate, blurred vision, increased dehydration, dizziness, nausea, headaches
Adverse Effects - Antihistamines
Drowsiness, diminished alertness, increased reaction times
Adverse Effects - Vasoconstrictors
Dizziness, blurred vision, tremors, headaches
Adverse Effects - Pain killers
Stomach irritation, dizziness, skin rashes, heartburn, blurred vision
Adverse Effects - Diet pills
Nervousness, tremors, increased blood pressure and heart rate, dehydration due to increased sweating, sleep disturbances
Alcohol
Perhaps the oldest drug known to man, alcohol is a legal drug having toxic effects on the body. It is a central nervous system depressant. Alcohol is absorbed through the stomach and upper tract of the small intestine and distributed throughout the body by the circulatory system. Can cause histotic hypoxia.
Effects - Alcohol
Psychological
: Impairment of Judgment and Performance
, Reduced Inhibitions, Abnormal Behavior Shifts, Pain Killers, Bolstered Sense of Immortality. Physiological
: Anesthesia,
Degraded Sensory and Motor Skills
, Decreased Visual Acuity
, Degraded Communication Ability
, Loss of Balance
Rate of metabolization of pure alcohol
The body metabolizes pure alcohol at a constant rate of one ounce in 3 hours.
AF policy with Alcohol
AFI 11-202 Volume 3, “A person must not act as a crewmember of an aircraft while under the influence of alcohol or its after effects.” and “Aircrew shall not consume alcoholic beverages within 12 hours of take-off.”
Carcinogens associated with tobacco
dipping, chewing, smoking, or inhaling tobacco
Effects of Smoking and Smokeless Tobacco
Increased blood pressure, heart rate, hand tremors, nausea, salivation, vomiting, cold sweat, headache, dizziness, disturbed vision and hearing, mental confusion, and marked weakness. Chewing or dipping tobacco increases the incidence of mouth, gum, tongue and cheek cancers.
Effects of CO
Increases physological altitude, decreases red blood cell carrying capacity of the oxygen, decreased oxygen transport to the eye, decreased resistance to hypoxia. Long term: lung damage, increased blood clots, cancer, cardiovascular disease
Hypoglycemia
Hypoglycemia results when the glycogen stores in the liver are depleted and there is not enough glucose in the blood stream. Hypoglycemia means “low blood sugar” and has a variety of causes.
How to prevent Hypoclycemia
The bottom line on nutrition and flying is to eat sensible meals containing complex carbohydrates low in fat (bagels, pretzels, fig/fruit bars, granola, milk, yogurt, fresh fruit), at regular intervals.
Dehydration
Is a major contributor to fatigue. When dehydration is combined with the flying environment, you fatigue quickly and are at a higher risk of experiencing decompression sickness, spatial disorientation, visual illusions, airsickness, and loss of situational awareness.
Dehydration - symptoms
Sensation of thirst, experience sleepiness, nausea, mental impairment, and mental and physical fatigue.
Fatigue
a state of diminished mental and physical efficiency
Causes and cures for acute and chronic fatigue
Acute fatigue is short-term fatigue caused by the normal daily activities of the crewmember. It’s remedied with a good night’s sleep and rest. Chronic fatigue is long-term fatigue and is caused by a variety of factors. For instance, when you fail to get adequate rest and sleep for several days. Also interrupted or poor sleep patterns, circadian rhythm shifts, illness, successive long missions with minimal recuperation time, and succumbing to self- imposed stresses.
Circadian Rhythm
Your body clock, 23-26 hour cycle for bodily functions
Circadian Rhythm Desynchronization
Fancy word for jet lag
Variables Affecting Circadian Rhythm
Direction of travel, magnitude of timezone change, interval between arrival and departure of next flight, relative difficulty of next flight, availability of DFAC, direction of destination, adapting to new time zone
Ways to reduce effects of fatigue
Get proper rest, naps before night flights <2 hrs, hydrated, no tobacco use, avoid high fat, high carbohydrate meals to reduce drowsiness. Bring “combat snacks.” During flight - turn down lights prior to landing to improve night vision, legal in flight naps
Caffine
Has ability to elevate mood, mask feelings of fatigue and increase the capacity for work. Effects: Dehydration, Restlessness, Nervousness, Faulty Thinking, Disturbed Sleep
Caffine - Withdrawl Symptoms
Headaches, Restlessness, Sense of Disquiet, Anguish, Aching Joints & Muscles
Caffine - Common Forms
Food/beverage, OTC drugs
Overload - Stress
In overload the demands are such as to exceed the individual’s ability to meet them. This can be viewed as a situation in which a person finds, in essence, opposed demand being made on him.
Common Stressors
Financial, family, professional and social responsibilities are a few of the stresses which may confront you
Methods to combat stressors
Place Demands into Perspective, Maintain a Healthy Diversity in Your Life, Eliminate Self-Imposed Stress, Aerobic and anerobic excercise
