AEROMEDICAL FACTORS

Medical Certification

All airplane pilots must be in possession of a valid Medical Certificate whenever exercising the responsibility of Pilot in Command, or when acting as a required crew member. A THIRD CLASS certificate is required for the Private Pilot not flying for hire.

The FAR’s prohibit a pilot from performing crew member duties when you have a known medical condition which would normally disqualify you for the certificate. This includes a relapse of a former condition, of an aggravation of a medical condition which would not qualify for the certificate during such aggravation.

Personal Checklist

Pilot impairment is a greater contributor to accidents than is aircraft failure. Such accidents may be due to medical conditions, exceeding your personal experience level, flying into weather conditions for which you are unqualified to handle, alcohol or drug use, stress, or an “attitude of get there at all cost”.

A good personal checklist is “IM SAFE”.

Illness

Medication

Many medications such as antihistamines, blood pressure medication, tranquilizers, pain relievers, and cough suppressants may have narcotic effects affecting mental and physical faculties. The safest rule is not to fly while taking any medication. If in question about any medication, consult with an FAA-designated Medical Examiner.

Stress

Stress, anger, and worry can affect a person's rational thinking process. The stress and worries detract from the ability to remain mentally alert. Such mental interference can blur judgment, memory recall, and impede attention to the flight environment. It is best to wait until the stressful situation has passed, and to fly safely another day.

Alcohol

The FAR’s prohibit pilots from flying or acting as a crew member within 8 hours of consuming any alcohol. This is the MINIMUM. A much better rule is 24 hours from bottle to throttle. Alcohol can significantly contribute to altitude oxygen deficiency as alcohol inhibits adequate oxygen absorption by the brain.

Fatigue

Fatigue may not be apparent until you have made a serious mistake. It may be a short term condition such as too little sleep the night before. All you need to recover is a good night's rest. It may also be a long term condition to which you have become accustom, but which prevents you from your peak performance. Such a condition requires a prolonged period of rest.

Fatigue leads to lethargy in the cockpit, impaired reasoning and judgment. It can lead to “getting behind the situation” if sudden unexpected situations occur.

Emotion

Emotion applies to your state of mind. You may be angry, irritated, or just mildly “out of sorts”. Obviously flying under these conditions is unwise. Emotion can also apply to your attitude about flying. Do you feel bold and invincible? Are you on the fence as whether the weather is go or no-go? Do you have a “must get there at all cost” mentality? Have you assessed your personal experience and capabilities for the given flight conditions? Have you set your “own go and no-go rules? Are you being bugged by a passenger “who has just got to get there NOW?

A good strategy is to evaluate your own experience, capability, and personal flight rules before you plan any flight. If the situation does not fit your pre-determined rules, THEN DON’T. When you feel uneasy about the flight conditions, the safest rule is wait for a better day or time. There is no cowardice in setting down and setting out the weather.

Scuba Diving

If you or a passenger have been scuba diving, you should allow sufficient time before flight to allow your body to rid itself of excess nitrogen in the blood. If this is not done, decompression sickness (the bends) can occur at altitude, creating a serious in-flight emergency.

For a dive which has not required controlled ascent, you should wait at least 12 hours before flying above 8,000 feet cabin altitude. For a dive that has required controlled ascent (decompression), the time allowed should be 24 hours for flight above 8,000 feet cabin altitude.

In-Flight Medical Conditions

The pilot should remain aware of several In-Flight conditions which can occur which will impair your ability to function adequately.

• Hypoxia
• Hyperventilation
• Carbon Monoxide
• Motion Sickness
• Sinus and Ear Block
• Spatial Disorientation
• Fear

Hypoxia

Hypoxia results from an oxygen deficiency. The lack of adequate oxygen affects the functioning of the brain and other organs. A sense of “well being”, belligerence, drowsiness, dizziness and headache can result. It has the same effect as early stages of inebriation.

Pilot performance can deteriorate significantly if operating at 15,000 feet for even a short time without supplemental oxygen. Visual acuity becomes impaired. Pheriperal vision turns gray, with only the central vision functioning (tunnel vision). Blue color (cyanosis) occurs at the extremities such as fingernails, and in the lip color.

At 15,000 feet you loose the ability to function correctly within 20 to 30 minutes. At 20,000 feet, these effects occur within 5 to 12 minutes.

Significant effects of hypoxia can occur at lower altitudes as a result of:

• Inhalation of carbon monoxide while smoking
• Small amounts of alcohol or certain drugs (antihistamines, tranquilizers, analgesics, sedatives).
• Extreme heat or cold
• Fever
• Anxiety or fear

Use of supplemental oxygen above 10,000 feet in day and 5,000 feet at night will inhibit the onset of hypoxia.

Hyperventilation

This is the abnormal increase in the volume of air breathed in and out. It can occur subconsciously when under stress or fear. The rapid breathing and excess oxygen flushes too much of the natural carbon dioxide from your system. The symptoms are dizziness, tingling of the extremities, hot and cold sensations, drowsiness, nausea and feelings of suffocation.

Recognition of these symptoms often lead to more apprehension and fear resulting in increased hyperventilation. Disorientation, muscle spasms, and unconsciousness if corrective action is not taken.

Corrective action can be breathing slowly into a paper bag held over your nose and mouth. Also, talking, singing, and counting out loud can assist in taking your mind off the apprehension causing the rapid breathing.

It should be noted that many of the symptoms are common to both hypoxia and hyperventilation. If you are using an oxygen system when symptoms occur, turn the oxygen regulator to 100%.

Carbon Monoxide

Carbon monoxide results from the incomplete burning of materials. It is usually found in engine exhaust and cigarette smoke. Carbon monoxide is tasteless, odorless, and invisible. It is however usually present in fumes which are detectable. In an aircraft, cabin air is heated by intake air flowing across the exhaust manifold. Lleakage of fumes from the exhaust system into the heated airflow can be dangerous. You should be particularly cautions when operating in cold weather.

Exposure of even a small amount of carbon monoxide over a long period of time can significantly impair pilot performance. Symptoms are feeling of sluggishness, headache, tightness across the forehead. These may be followed by increasing symptoms of throbbing in the temples, or ringing in the ears. Large accumulations can lead to vomiting, convulsions and death.

Motion Sickness

Motion sickness from the stimulation of the inner ear which controls your sense of balance. The symptoms are progressive. They are loss of desire for food, excessive saliva, perspiration, nausea, and tendency to vomit.

If you or a passenger are suffering from airsickness, you should:

• Open air vents
• Loosen clothing
• Use supplemental oxygen if available
• Keep eyes on a point outside the aircraft
• Avoid rapid or unnecessary head movements
• Land as soon as possible

Pilots susceptible to motion sickness should NOT take motion sickness drugs. Research has shown these drugs may cause temporary disorientation, loss of navigational skills, or other functions which demand keen judgment.

Sinus and Ear Block

During ascent and decent the pressure inside the sinuses normally adjust to the cabin pressure. Conditions such as colds and nasal infections can significantly close the passages which permit this pressure equalization. This causes sinus block. It can cause significant pain in the affected sinus region, tooth ache, and mucus discharge from the nasal passages.

During decent, the Eustachian tube of the middle ear opens to allow pressure relief into the nasal passages. During decent the pilot should periodically reopen the Eustachian tubes by swallowing, yawning, tensing muscles in the throat or chewing. If this fails, blowing with the nose with the mouth closed and the nose pinched off can usually equalize the pressure.

A cold or ear infection can produce enough mucus in the Eustation tube to prevent pressure equalization. This results in ear block.

If either sinus block or ear block persists for some period after landing , consult a physician. Rupture of the ear drum or infection in the ear can result from failure to relieve the condition after some period of time.

Spatial Disorientation

Spatial disorientation (formerly referred to as vertigo) results from loss of visual contact with terrain or other visual reference points. It is the result of confusing sensations sent to the brain by the muscles and inner ear when visual reference is lost. One cannot tell whether they are ascending, descending or turning.

It is a REAL threat to the VFR pilot who has had insufficient training in flying solely by reference to instruments. Much of the training of instrument pilots is devoted to the reliance and interpretation of the instruments instead of their sensations.

Situations which can quickly lead to spatial disorientation are:

• Flight into cloud
• Flight at night over unlighted terrain (loss of horizon reference)
• Facing the sun in haze condition
• Flying above a cloud layer with sloping top

If inadvertently caught in such condition, DON’T PANIC. If you have been trimmed out for straight and level, do not make any drastic or sudden moves in the attitude of the aircraft. LOOK AT YOUR COMPASS HEADING.

Get On The Gauges. Concentrate on flying by the instruments. Learn how to use them and to trust them. Keep a level attitude. Your worst enemy is getting into a steep bank. If need be, turn the aircraft with light rudder pressure only, with hands off the wheel or stick. Even though this is an un-coordinated turn, you will not get the aircraft into a dangerous unusual attitude. Try to get out of the condition by slowly doing a 180° turn, or a turn away from the conditions causing the disorientation. Keep your angle of bank 15° or less. A 15° bank will take you 1 minute to complete a 180° turn.

Fear

We all at times experience fear. The question is how do we respond to fearsome situations. Flying is not without it’s anxious moments. It is easy to say “DON’T PANIC”; but that is exactly what is required of the pilot in command.

The best defense against fear is TRAINING. This is why your instructor will put you into situations which will test your perception and judgment skills. Even after you obtain your private license, continue to train and learn. Flying is a lifetime learning experience. After you have achieved some experience, consider obtaining an instrument rating. Weather situations will be the prime cause for anxious moments. The more confidence you can gain in handling instrument conditions, the safer you will be.

This does NOT mean pushing yourself beyond your training; rather it means getting the training and experience to handle whatever situation that may arise. There is a trite but true saying that “there are bold pilots, and there are old pilots; but there are no old bold pilots”. There are however many old experienced pilots around who have flown thousands of hours safely and with confidence. Ability and confidence is the key to handling fear.

Vision

Good vision is important to safe flying. The eye contains two different light sensitive nerve endings called the RODS and the CONES. They are located in the back of the eye in the area called the retina.

The CONES are concentrated around the center of the retina, and decrease in number as the distance from the center of the retina increases. They are the nerves which predominately detect color, details and distant objects. They function in daylight and moonlight.

The RODS are concentrated around the area of the cones, and increase in number as the distance from the center of the retina increases. Their function is to detect objects in motion out of the corner of the eye (peripheral vision). They function in daylight, moonlight and darkness.

This is an important concept to understand with regard conflict avoidance with other aircraft. During the day, objects can best be seen by looking directly at them. Your scan for other aircraft and objects should be in deliberate scan increments of about 10 degrees. Look at this area for several seconds, then look at the next 10 degree increment in your scan. Pausing to concentrate on a given area of vision is important since the eye cannot detect distant objects when in a continuous scan movement.

At night, vision is more dependent on the RODS. “Off-center viewing” is best. The eye is more adept to seeing objects through the use of peripheral vision. With some practice, you can see objects better by using “off center” viewing rather than looking directly at them.

When entering darkness, the pupils of the eye enlarge to receive as much of the light as possible. It will take 5 to 10 minutes for the adjustment to increase your “dark” vision by a factor of 100. After 30 minutes, the rods will be fully adjusted, and the rod’s sensitivity to light will become approximately 100,000 times more sensitive to light than in bright light.

For night flight, you should allow your eyes to adapt to the darkness for some time to achieve best night vision acuity. Once your vision has adjusted, guard against exposing your eyes to bright light, as temporary blindness and illusion can result.

Night vision can be adversely by low oxygen levels at altitude. It is best to keep cabin altitude to 5,000 feet or less at night. In higher altitude is necessary, use of oxygen is advised. Smoking can reduce night vision by as much as 20%.

Personal Evaluation

Often pilots are tempted to demonstrate their skill to others, and to prove they are made of the right stuff. This leads many pilots into serious pitfalls. Every pilot should continuously and HONESTLY evaluate their medical fitness for flight, and their skills and competency.

Pitfalls

All experienced pilots have at one time or another had to face some dangerous attitude situations and pressures. Some of these are:

• Peer Pressure - This is based on an emotional response to equal or exceed the skills of your peers which push you beyond realistic evaluation of your situation
• Mind Set - may make you fail to realistically recognize and cope with the situation.
• Get There At All Costs- this can result in business schedules or friends who are relying on you “to get there”. This is probably the greatest single cause of weather related accidents. It causes one to “press on” to the initial objective, rather than select safer alternative actions when things do not go as planned. There is no shame in “setting out the weather”.
• Duck Under - the tendency for pilots to go below “minimums” on an instrument approach to “sneak a peek” hoping to avoid a “missed approach”.
• Scud Running - is trying to fly below the scud (clouds) without hitting the ground. It’s trying to make it there in poor MVFR ( or less) conditions by dodging the clouds at low altitudes and visibility.
• Continuing VFR into IFR Conditions - Continuing flight into weather conditions adverse to VFR flight.
• Getting Behind the Aircraft - this occurs when events are controlling you instead of you controlling the events.
• Loss of Positional Awareness - its the situation where your instructor says “Enough for today, take me back to the airport”; and you have no idea which way it is. You have been so occupied with other matters that you do not know where you are.
• Operating with Inadequate Fuel Reserves - This occurs when the pilot fails to properly plan the trip, fails to observe flight progress, and becomes non-responsive to the VFR and IFR fuel reserve regulations. It also occurs to pilots who are lost, and delay getting help from ATC.
• Inadequate Planning - Failure to plan the course and alternative actions. Negligent pre-flight inspection. Failure to use check lists. Failure to maintain positional awareness in flight.

Hazardous Attitudes

• Authority (Don’t tell me what to do)
• Impulsivity - (Do Something NOW!)
• Invulnerability - (It won’t happen to me)
• Macho - (I can do anything)
• Resignation - (What’s the use)