Aeromedical Factors

Aeromedical Factors Notes:

Pilot Personal Checklist - 

I - Illness

M - Medications

S - Stress

A - Alcohol

F - Fatigue

E - Emotion

Obtaining a Medical Certificate - 

Medicals acquired by Aviation Medical Examiner (AME).  There is a directory of these examiners kept at FSDOs and other FAA offices.  A student pilot receives a combined student pilot certificate and medical.  3 Classes of medical - each with different privileges and requirements (14 CFR Part 67/61).

•3rd Class - valid for Private/Recreational pilots.  If under 40, valid for 3 years.  Over 40, valid for 2.

•2nd Class - for commercial pilots.  Valid for 1 year.

•1st Class - for ATP pilots, valid for 6 mos.

Physical Limitations / Conditions & Solutions

Depending on situation, certain equipment may need to be installed on aircraft to aid in pilots with disabilities.  Others may require limitations upon the certificate itself.  If pilot can demonstrate that they can safely operate an aircraft, a Statement of Demonstrated Ability may be issued (SODA).  Details at http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/general/appeals/soda/.

Health / Physiological Factors

•Hypoxia - lack of oxygen in either blood, brain, or lungs.

Symptoms - Cyanosis, headache, drowsiness, dizziness, euphoria, tunnel vision.

Remedy - Descend promptly, use supplemental oxygen, turn off Cabin Heat

There are 4 Types of Hypoxia - Hypoxic, Hypemic, Stagnant, and Histotoxic

Hypoxic - Insufficient oxygen in body as a whole.  Flying at high altitudes is common culprit.  While percentage of oxygen at altitude remains the same, its pressure is reduced (fewer molecules to breathe).

Hypemic - Blood is unable to transport oxygen.  Common culprit is CO2 poisoning.  Could also be result of anemia or donating blood.

Stagnant - Blood has oxygen, but isn't moving.  Can result from G-forces or cold temperatures.

Histotoxic - Cells have received the oxygen, but unable to use it.  This impairment is caused by alcohol and other drugs.

•Hyperventilation - Excessive rate and depth of respiration leading to abnormal loss of CO2 from the blood.  Often caused by stressful situation.  

Symptoms - Rapid breathing, unconsciousness, visual impairment, tingling, muscle spasms

Remedy - Breathe into paper bag and consciously concentrate on slowing breathing.

•Middle Ear/Sinus Problems - During climbs and descents, free gas expands due to difference in pressure within body and outside.  If gas cannot escape readily, pressure builds up and causes pain.

In middle ear, Eustacian Tube allows pressures inside middle ear and outside to equalize.  In climb, tube expands.  In descent, in constricts causing discomfort.  This is hampered more by sinusitis or a cold.  Decongestants may help, but should be verified safe by an AME.

•Spatial Disorientation / Illusions - Pilot's lack of orientation regarding movement of airplane, position, and attitude.  Body uses 3 systems to sense its position in space.
1) Vestibular - organs in inner ear - sense of balance
2) Somatosensory - nerves in skin, muscles, and joints - sense position based on gravity and feeling
3) Visual - eyes which sense position based on what they see

In Visual flight conditions, pilots typically depend on visual cues, which are often able to correct for false senses from the other physical sources.  Difficulties are often encountered when flying on instruments.

Vestibular system is easily tricked.  The inner ear contains canals with fluid and tiny hairs.  These sense motion.  For example, a climb causes these hairs to move back, but so does acceleration.  These two sensations could be confused if unable to see outside the plane.  Furthermore, a maneuver that is well coordinated and slow may not cause any sensation in the inner ear.  This could result in a pilot entering a graveyard spiral when they attempt to climb (they are actually tightening spiral).  The best remedy is to rely on instruments.

Visual illusions - pertain mostly to false horizons or obscured horizons.  This can occur if there is sloping terrain or a haze that obscures the actual horizon.  These are especially acute at night when there is less to see.  Autokinesis is another night-flying concern as staring at a stationary light will cause it to move about.

Furthermore, runways themselves can be illusions.  Upsloping or narrow runways, for example, give pilots the illusion that they are too high - resulting in a lower than normal approach.  Rely on VASI and PAPI indicators if available and become familiar with runway lengths and widths prior to landing.

•Motion Sickness stems from the brain receiving conflicting messages about the body.  The inner ear is being over-stimulated  Anxiety/stress can contribute.
Symptoms include nausea, dizziness, paleness, dry mouth, and sweating.
Remedies include landing promptly, opening air vents, loosening clothing, instructing sufferer to focus on the horizon.

•Carbon Monoxide Poisoning is essentially a form of hypoxia (hypemic).  This is mostly triggered by aircraft cabin heating systems which redirect heat from the manifold exhaust shroud to the cabin.  If there is a crack in the manifold, poisonous exhaust gases may enter the cabin.
Symptoms include drowsiness, blurred vision, headache, dizziness.
Remedies include turning off cabin heat, opening air vents, descending rapidly.

•Stress is often difficult to diagnose and treat because it can be heavily internalized.  However, each pilot should be able to recognize the stress factors in their life and how they could jeopardize the safety of the flight.  Ultimately, the pilot does not want to be distracted.  A pilot experiencing a recent bad breakup with a significant other or death in the family should not fly.

•Fatigue like stress may seem benign, particularly because pilots often face demanding schedules.  A fatigued pilot has slower reaction times and has less concentration.  Again, if the pilot is so fatigued, that they become distracted from their primary duties, they should not be flying.  Only more rest can correct fatigue.  Red Bull and coffee are not solutions.

•Dehydration is a lack of water in the body.  This can occur on hot days, or consumption of caffeinated drinks.  The body experiences fatigue and headache.  Bring water on board - even on short flights.

Alcohol/Limitations
Alcohol impairs the body at sea level.  With an increase an altitude, these effects are magnified.  Even a small amount can reduce reaction time, impair vision, and impair judgement.  Pilots must not drink within 8 hours before a flight and cannot have more than .04% alcohol in their system.  (14 CFR Part 91).  Common sense should step in.  Even if your flight is more than 8 hours away the following morning, drinking the night before is not wise.  A hangover is just as damaging to pilot judgement and makes flying an unpleasant experience for all involved.

Drugs

While we often think of illegal narcotics as being hazardous, even over-the-counter medications can pose a risk.  Almost all drugs have side effects, which could become more pronounced at altitude.  Something like Tylenol is not of great concern, stronger pain killers could cause mental confusion and nausea.  This is obviously not safe for flying.  If you are unsure of the safe use of medication and flying, consult an AME.

SCUBA / Decompression concerns
When SCUBA diving, an excess nitrogen remains in the system.  If the body enters a state of low pressure too soon, this gas forms bubbles, which is not only extremely painful, but can be fatal.  The best remedy for this is time to allow the gas to dissolve completely prior to flying.  In most cases, wait 24 hours.  If there was not a controlled ascent and you are flying less than 8,000 ft, 12 hours is deemed sufficient.  Although airlines are pressurized for 6-8,000 ft, you cannot rely on them being pressurized the entire time.  A sudden decompression would be extremely hazardous to someone who did not allow enough time after SCUBA.

Vision
Particularly in Visual flight conditions, eyes are extremely important.  Its main light-sensitive components are Rods and Cones.

Cones - are responsible for all color vision and are located near the center of the field of vision.

Rods- are better for detecting motion and are better suited for low light.  Therefore, during the day, cones are better suited for looking for traffic, and at night Rods are more effective.  Rods do, however, take longer to adjust because they are so sensitive to light.  This is why pilots must wait at least 30 mins. for their eyes to adjust to the darkness after looking at a bright light.