Ch 8 - Hazards Of Aviation & Personal Health And Hygiene Flashcards
Acceleration and the 3 variants
Change in velocity (speed and direction)/ Time
Linear - Constant direction, changing velocity
Radial/Centripetal - Change in direction and speed
- An axis external to the pilot
- Most disorientating
Angular/Transverse - Aircraft is in balance
- Axis is through pilot’s body
G - Forces and the 3 axis
1G = What we feel supporting our own weight
Can be +/-
Gx - Fwd and Back +/-
Gz - Up and Down +/-
Gy- Lateral Right+/Left -
Effect of +Gz
The body is far more tolerant of Positive G
Gz >/= 1G - Pooling of blood in our lower limbs
- Increased hydrostatic variation
- Blood Pressure decreasing
Gz>= 2G - Feeling slightly heavier (2x More body weight)
- Mobility Impaired
Gz~3G - Facial features and internal organs pulled down
Gz~3.5G - Starve rods of O2, vision comes in from peripheral
- Lack of O2 to brain = Grey Out = Tunnel vision
Gz~4-5G - Organs and diaphragm going even more down, breathing and respiratory problems
Gz>=5G - Full black out G-LOC
Effects of -Gz
Can only withstand -2/-3G
- Blood and organs forced up
- Blood rushes to the brain
- Hydrostatic variation decreases
- Blood pressure increases causing pain in the head, headaches and sore head muscles
- Lower eyelids pushed up
- HR will start to drop
- Will eventually red out - Just see red - blood in the brain and pass out
Long Term Duration
Considered anything equal to or over 1s
+3.5Gz relaxed
+7-8Gz in anti-G suits or compression suits
- Clench muscles (legs and abdominals)
- Scream, cough, bent fwd or supine
Short Term Duration
Considered anything less than 1s
+25G Vertical which cockpit seats are built to withstand
+45G fwd/back
-2/-3G
Factors that reduce tolerance
Smoking Obesity Heat Stress Alcohol Fatigue Hypoxia Hyper/hypotension Hypoglycaemia
The Physiological affects depend on:
4 Things:
Magnitude of Acceleration
Direction
Duration
Onset Rate
Somatogravic Illusion
Caused by linear acceleration (the Otoliths(utricle and saccule)
- Hairs in the otoliths go back which makes the head think it is climbing
Accelerate = Think climbing Decelerate = Think descending
Very very powerful - Overriding the instruments and hard to change perception
Trust your instruments
Somatogyral Illusion (the leans)
Caused by angular acceleration (the semi circular canals )
- Hairs and liquids which turn with the turn
- If prolonged, will go back to normal position so when you return to S&L, your body thinks you have over corrected so you return the aircraft to the original turn §
Graveyard Spin
Caused by radial acceleration
Aircraft spinning in no visibility is very disorientating
- Similar to somatogyral in that the hairs go with the turn, then return to neutral, then as you return the aircraft to S&L, you think you have over corrected so turn back into the original spin, pitch up to reduce the decent, tightening up the turn, moving you faster towards the ground
Trust your Instruments
Corioless Illusion
Caused by simultaneous stimulation of several of the semi circular canals
Which your vision then corrects as 70% of your perceptive information comes from your vision
Oculogravic
Sort of backs up the somatogravic illusion
When you accelerate, you vision gives you the illusion of climbing
Deceleration does the opposite
Oculogyral
Caused by lateral acceleration.
Backs up the somatogyral illusion in that your vision tricks you into thinking you have overcorrected after a prolonged turn
Vertigo
The feeling of tumbling, dizziness or turning sensation caused by more than one sense stimulated
Pilots Vertigo - Corioless illusion, stimulates more than 1 sense, ear infection makes it worse along with a turning or climbing manoeuvre
Flicker Vertigo (Epilepsy) - Most disorientating with flickers ranging from 5-20+ flickers per second
Turn off strobes when in cloud at night or change heading when facing sun in clear day
