Aeromedical Factors
Nov 09, 2017Aeromedical Factors
Aeromedical factors is a big part of your pilot training and should continue to be a big part in you everyday piloting.
We need to be aware of these for the written test, check ride, and most importantly..... SAFETY
From the Helicopter Online Ground School archives of live interactive training.
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The "IM SAFE" checklist
Illness, Medication, Stress, Alcohol, Fatigue, Eating
Aeromedical conditions
1. Hypoxia and carbon monoxide poisoning
Symptoms (may be hard to recognize before reactions are affected): euphoria, impaired judgment and reaction time, headache, drowsiness, dizziness, tingling fingers and toes, numbness, cyanosis (blue fingernails and lips), limp muscles.
Time of useful consciousness:
20,000 MSL 30 minutes
22,000 MSL 5 to 10 minutes
30,000 MSL 1 to 2 minutes
40,000 MSL 15 to 20 seconds
a. Hypoxic: inadequate oxygen supply, as in our breathe-out scenario.
b. Hypemic: Inability of blood to carry oxygen, mostly as a result of inhalation of carbon monoxide (including from cigarette smoke).
c. Stagnant: Poor blood circulation. In aircraft this can happen through G forces or cold.
d. Histotoxic: Inability of cells to use oxygen, mostly from alcohol or drug use.
Carbon monoxide can come in through the heating system. If you ever smell exhaust, or suspect that carbon monoxide is coming in the cabin, turn off the heater, open windows and vents, use supplemental oxygen if available, and land as soon as possible. CO can stay in the body for 48 hours.
2. Hyperventilation
Too little CO2 in the body results in distruption of normal breathing, resulting in symptoms like that of hypoxia: drowsiness, dizziness, shortness of breath, cyanosis, plus feelings of suffocation, paleness, clammy skin, muscle spasms. It's usually triggered by stress (fear, anxiety), and passengers are susceptible. Corrective actions to slow breathing and increase CO2: talk aloud or breathe into a paper bag.
Aeromedical Factors
3. Middle ear, sinus, toothache conditions
The difference between atmospheric pressure and pressure in the ear can cause discomfort. Normally the Eustachian tube will open to equalize the pressure. This can be assisted by chewing, yawning, swallowing, or using the Valsalva maneuver. A cold, infection, or sore throat can make equalization more difficult, which can be painful or even dangerous to the eardrums. Minor congestion can be combated with medications or drops or sprays, but check with your physician. (Falling asleep at the yoke is bad.)
4. Disorientation
Kinesthetic sense is unreliable, because the body can't tell the difference between gravity and G-loads. Visual illusions (e.g. at night) can make it worse. You'll find out all about this when we do hood work.
Vestibular disorientation comes from forces on the hair cells of the three semicircular canals in your inner ear. (Show picture)
Illusions:
a. Coriolis illusion: moving the head quickly creates an illusion of rotating or turning
b. Graveyard spiral: prolonged constant-rate turn may be interpreted as wings-level descent.
c. Leans: recovery to a bank is interpreted by inner ear as a roll in the opposite direction
d. Somatogravic illusion: acceleration feels like nose-high, deceleration like a dive
e. Inversion illusion: change from climb to level feels like tumbling backward
f. Others: autokinesis, haze, false horizons, empty field myopia, runway slope/width
5. Motion sickness
You probably know these symptoms. It's just like being car sick, and the source is the same: the brain is receiving conflicting signals from the eyes, body, and inner ear. (This is why reading in the car makes it worse.) You can become inured to this over time, but your passengers may not. It's probably best not to mention this to them before you get in the plane, but do carry sickness bags with you. Corrective measures: open fresh air vents, take deep breaths, put the head back and close eyes, focus on things outside the helicopter.
6. Alcohol and drugs
MM-Kay, drugs are bad, mm-kay. You shouldn't do drugs. Alcohol is bad; you shouldn't drink alcohol, mm-kay…
No, but seriously: what are the FARs concerning alcohol? Eight hours bottle to throttle, and not have a blood alcohol above .04. (If you have a blood alcohol level of .04 after not drinking for eight hours, you were in sorry shape indeed, and the hangover, as well as your better judgment, should keep you from flying.)
The FARs also indicate that if you're taking any medications that you believe make you unsafe to fly, then it's ILLEGAL for you to fly.
7. Scuba Diving
Nitrogen buildup is unavoidable and can cause the bends (decompression sickness).Before going to 8,000 MSL, wait 8 hours after a dive that has not required a decompression stop, and 24 hours after a dive that has required a controlled ascent (decompression stop). To go higher, wait 24 hours after any dive.
Aeromedical Factors
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