Threats To Aviation Flashcards
Hypoxia
Insidious Hypoxia = major threat to flight crew
Ensure supply of oxygen above 10,000ft
Passengers bring
Stop smoking
Only fly when fit
Decompression Sickness Cause
Ambient temp reduces at altitude
Bubbles merge to become larger bubble (Air embolism)
Become trapped in joints and block normal passage of blood
Tissue downstream of blockage deprive of o2 and dies
When is decompression sickness likely
18,000-25,000ft unlikely below 14,000ft
Factors of DCS
High alt
Duration of exposure
Age
Excess body weight
Scuba diving
Symptoms of DCS
Bends - Bubbles in joints NO1 symptom
Creeps - bubbles under skin
Chokes - Bubbles in capillaries and lungs
Staggers - bubbles in brain
DCS Treatment
Descend (Nitrogen to dissolve back into solution)
100% oxygen
Urgent medical assistance on landing
Scuba Diving on DCS
Compressed air - descent increases partial pressure of nitrogen so saturation of nitrogen increases in tissue
Takes time to excrete excess nitrogen
Risk of flying even at cabin alt of 6000ft
(PREVENTED BY BREATHING 100% OXYGEN)
Scuba Diving rules and flying
Do not fly 12 hours after diving or use of compressed air
Avoid flying 24 hours if depth of 30ft exceeded
Acceleration durations
Long = 1+ sec (+3.5G relaxed/7 to 8g using anti straining techniques)
(-3G but only short periods)
Short = less than 1 sec
(+25G in vertical axis)
(+45G in fore/aft axis
Gx
Linear (fore and aft)
Forward acceleration
Gz
Vertical acceleration
Heavier
More blood to feet than brain
Hydrostatic variation increases
Gx
Linear - sensory illusion in pitch axis
Somaticgravic illusion
Large forward acceleration makes you feel as though pitching up
Large rearward acceleration makes you feel as though pitching down
Vertical Gz effect on body
Increase in body weight so harder to move (2g above mobility impaired)
Increase in hydrostatic variation of the blood pressure
+G force stages
Grey OUT (3/4G) - Rod and cones need disproportionate amount of oxygen causing tunnel vision
Black out - (5G above) lose consciousness
Negative -G effects
Organs force upwards/blood forced to head (decreased hydrostatic variation)
Respiration difficulties/facial pain/red out/lower eyelid pushed up/slower hear rate
Barotrauma
Injury caused by pressure differential
Otic Barotrauma
Ear
Worse in descent when air attempting to return to middle ear
Eustachian tube one way valve
Sinus Barotrauma
Sinus — inside facial bones around nose blocked by mucus and infection
If you experience this stop descent return to previous altitude and slowly descend again
In climb stop climb and land asap
Aerodontalgia Barotrauma
Gas pockets in old or poor fillings
Commons in the ascent as gas expands
Not occur in descent
Gastro-Intestinal Barotrauma
Gas expanding in small intestine
Humidity in cabin
5-10% (Prevent corrosion to airframe and electrics)
Incapacitation
Gastro main cause
UNCLEAN FOOD OR WATER
High Altitude flying millisieverts limits
Max 20 mSv a year
Alcohol Effect
1 unit per hour (15mgs/100ml per hour)
Rate of elimination slows down during sleep
Bends
Bubbles in joins
Descending can reduce symptoms
Most common symptom of DCS
Creeps
Nitrogen bubbles under the skin
Chokes
Nitrogen bubbles in capillaries of the lungs
Staggers
Nitrogen bubbles in blood supply to brain and nervous system
Uphill terrain
Uphill slope = appearance of being too high
Downhill Slope
Illusion of being too low
Alcoholism symptoms
Higher tolerance to alcohol
Withdrawal symptoms
Conflict with the law
Alcohol Consumption
No alcohol should be consumed less than 8 hours prior to reporting time for flight duty
Blood levels should not exceed 0.02% at start of flight duty and duty period
Average amount of cosmic radiation flight crew receive per year
Equal to amount of background radiation
Average around 4.0 mSv per year
MAX IS 20mSv
Which combination of factors associated with alcoholism
Genetics
Access to cheap alcohol
Social cultural background
Reversion
Usually in emergency under pressure - automatically doing what you used to as under pressure
What is a fume event
Abnormal odours, smoke, haze or fumes in the cabin
Toxic environment created by contaminated bleed air
Can include:
- fire extinguisher discharge in cockpit
- eye irritation
- carry on baggage
- cleaning products
- food items
