Human Factors 1 Flashcards
1
Q
Atmospheric Pressure
A
- 29.92 at seavel
- half at 18000 ft
- quarter at 34,000 ft
- 10th at 54,000 ft
2
Q
Decreased Atmospheric Pressure
A
- Causes fall in pressure gradient at which oxygen is delivered to the lungs, results in hypoxia
- Causes an expansion of the body gases, results in dysbarisms and decompression sickness
3
Q
Atmosphere - Decrease of Partial Pressure
A
Causes Hypoxia
4
Q
Atmosphere - Decrease of Total Pressure (Trapped Gas)
A
Causes Dysbarisms and Abdominal Pain
5
Q
Atmosphere - Decrease in Total Pressure (Evolved Gas)
A
Causes Decompression Sickness
6
Q
Hypoxic Hypoxia
A
- Lack of oxygen in the air
- Normal Effect of altitude
- Insidious, first symptom is Euphoria
7
Q
Anaemic Hypoxia
A
- Too few blood cells or too few haemoglobin to carry the oxygen
- Usual cause is poor diet or loss of blood
- Also caused by carbon monoxide blocking haemoglobin, exhaust fumes,
- Smokers have 5-8% of haemoglobin blocked by CO2
8
Q
Stagnant Hypoxia
A
- Caused by reduced bloody supply to the tissues
- Most common cause is high G-loads
9
Q
Histoxic Hypoxia
A
- Caused by interference from enzymes that require oxygen to produce energy
- Type of chemical poisoning
- Certain drugs or medicine can cause it
- Can be caused by high blood alcohol levels
10
Q
Night Vision
A
- Retina of eye is very sensitive to hypoxia
- Night vision marginally reduced at 5000’
- Night vision reduced by 25% by 8000’
11
Q
Hyperventilation
A
- Breathing more rapidly than necessary
- May be obvious or barely noticeable
- common to over breathe while under stress
- can be exaggerated by anxiety and panic
- Body reduces oxygen pressure at the brain, resulting in brain hypoxia
- Warning signs are dizziness and pins and needles
- Continued hyperventilation leads to Muscular spasms and unconsciousness
12
Q
Treatment of Hypoxia and Hyperventilation
A
- If below 8000 ft, hypoxia unlikely, slow breathing rate to 12/min
- If above 8000 ft, take 3-4 breaths of oxygen/descend below 10,000 ft, if problems persist, treat as hyperventilation
13
Q
Gas Expansion Effects - Ear
A
- If Eustachian tube becomes blocked or plugged, eardrum will not vent and could rupture
- Most likely on descent when pressure increases, since valve flaps OUT of ear
- If experiencing ear pain on descent, climb back to original altitude, and descend slowly, clearing ears every few hundred feet with the valsalva technique
14
Q
Gas Expansion Effects - Sinuses
A
- Air pockets above the eyes, behind the nose, and in each cheek
- Drainage tubes can become blocked due to a cold or hay fever
- If experiencing ear pain on descent, climb back to original altitude, and descend slowly
15
Q
Gas Expansion Effects - Teeth
A
- Dental cavity may have trapped air beneath loose filling
- Can cause severe pain due to air expanding as you climb
- Trapped air in a dental abssess can also cause pain
- Return to lower altitude
16
Q
Gas Expansion Effects - Bowels
A
- Gas always present in bowels
- Trapped gas will expand during a climb
- usually passed as flatulence
- If air gets trapped in bowels, can cause severe discomfort
- Pilots should avoid food that causes gas production
17
Q
Decompression Sickness
A
- Caused by release of nitrogen in form of gas bubbles from tissues as pressure decreases
- Normally accumulates around joints and can form arthritis
- Symptoms do not occur below 20,000 ft under normal circumstances
- Creeps, Cramps, Chokes, Collapse
18
Q
Decompression Sickness - Creeps
A
- Itchy sensation caused by tiny gas bubbles under the skin
- Not a serious issue by itself, could be early warning to more serious effects
19
Q
Decompression Sickness - Cramps
A
- Pains in joints due to air bubbles interfering with blood flow
- Known as the “classic bends”
- Pain is dull and may become severe
- Exercise only make it worse
- Symptoms can be relieved by descending to a lower altitude
20
Q
Decompression Sickness - Chokes
A
- Feeling of difficulty breathing and pain behind the breastbone
- Occurs when bubbles get into lung circulation
- Sufferer will look ill, and may appear to be having a heart attack
- Immediate descent must be made
21
Q
Decompression Sickness - Collapse
A
- Final symptom, occurs when large bubbles interfere with blood supply to the brain
- Fairly uncommon
- Pilots more common to get bubbles in the brain, divers in the spinal cord
- If experiencing, see doctor immediately
22
Q
Decompression Sickness - Scuba Diving and Flying
A
- After non-decompression dives, don’t fly for 12 hours if flying below 8000 ASL
- For compression dives, don’t fly for 24 hours if flying below 8000 ASL
- If flying above 8000 ASL, must wait 24 hours for all dives
23
Q
How The Eye Sees
A
- Cornea resolves image
- Lens focuses image to centre of retina at back of eye
- Retina connected to nerve cells, cell fibers meet to become optic nerve
- Optic nerve runs to visual area of brain
24
Q
Sector Scan
A
- Divide sky in 30º segments, slowly focusing on each
- Scan 10º above and below the horizon
- Use peripheral vision to detect movement
- Use central vision to lock-on and recognize
25
Empty Field Myopia
- Occurs when field of vision is empty
- At high altitude or at night
- Focus of eye drifts in to a distance of 2 meters
- Pilot must constantly focus the eye to infinity to maintain a good lookout (Look at distant object such as cloud, ground feature, or wingtip)
26
Design Eye Reference Point (DERP)
- Position of pilot's eyes for best view of instruments and outside the cockpit
- Not in POH of most light aircraft
- Should be able to see ground 40 feet in front of where the aircraft is parked
27
Kinaesthetic Illusions
- Flying by the seat of your pants
- Subconscious orientation sense we use in flight
- Can be dangerously unreliable when peripheral vision is limited
28
Visual Illusions - White out and Black Holes
- Lack of Contrast
- Makes depth perception practically impossible
29
Visual Illusions - False Horizons
- Haze layers
- Cloud tops
- Ground lights and stars may be confused
30
Visual Illusions - Vectional Illusions
- Illusions of false movement
- Car beside you creeping forward at a stop light
31
Visual Illusions - Autokinesis
- Small fixed light viewed steadily at night appears to move
- Caused by the eyes losing fixation
- Can be overcome by looking away and then back again
32
Vestibular Illusions
- Most complex and dangerous illusion
- Otoliths respond to linear acceleration
- Semi-circular canals respond to pitch, roll, and yaw
- Work similar to swishing a glass of water
- Accurate on the ground, but can be inaccurate in flight
33
Vestibular Illusions - Linear Accelerations
- Information provided by Otoliths
- Aircraft acceleration is a pitch up illusion, tendency to pitch nose down on takeoff
- Aircraft deceleration is a pitch down illusion, tendency to pitch up on transition to approach
34
Vestibular Illusions - Angular Accelerations
- Information provided by circuler canals
- Can cause opposite turning illusion after pilot rolls out of a turn
35
Coreolis Effect
- Caused by inappropriate head movements
- Can create a violent sensation of tumbling
- Turning the head sharply is extremely hazardous, expecially turning against the turn
36
The Leans
Pilot feels banked attitude when straight and level
37
Fatigue
After 17 hours awake, a person performs as well as a person with a BAC of 0.05, and 1.0 after 24 hours
38
Sleep Stages
- Transitional, sleep-awake, slow wave, deep sleep
- Slow wave is where REM occurs, must have REM to properly rest
- Deep sleep associated with physical restoration, growth, and the body's immune system
39
Pilot Fatigue Considerations
- Try to get 10 hours of sleep the night before a shift change
- If tired and circumstances allow, take a 30-45 min or 90 min nap, NASA nap
- If fatigued in flight, try to do something that requires thinking
40
Jet Lag
One day's recovery time per time zone of difference
41
Pregnancy
- Grounded at latest by week 30 for as little as 4-6 weeks
