Chapter 8

CHAPTER 8
AEROMEDICAL FACTORS

A. Fitness for Flight

1. What regulations apply to medical certification?

Part 67 – Medical Standards and Certification.

2. As a flight crewmember, you discover you have high blood pressure. You are in possession of a current medical certificate. Can you continue to exercise the privileges of your certificate? (AIM 8-1-1)

No, the regulations prohibit a pilot who possesses a current medical certificate from performing crew member duties while the pilot has a known medical condition or an increase of a known medical condition that would make the pilot unable to meet the standards for the medical certificate.

3. Are flight crewmembers allowed the use of any medications while performing required duties? (AIM 8-1-1)

The regulations prohibit from performing crewmember duties while using any medication that affects the faculties in any way contrary to safety. The safest rule is not to fly as a crewmember while taking any medication, unless approved to do so by the FAA.

4. Are there any over-the-counter medications that could be considered safe to use while flying? (AIM 8-1-1)

No; pilot performance can be seriously degraded by both prescribed and over-the-counter medications, as well as by the medical conditions for which they are taken. Many medications have primary effects that may impair judgment, memory, alertness, coordination, vision, and the ability to make calculations. Also, any medication that depresses the central nervous system can make a pilot more susceptible to hypoxia.

5. What are several factors which may contribute to impairment of a pilot’s performance? (AIM 8-1-1)

Illness
Medication
Stress
Alcohol
Fatigue
Emotion

B. Flight Physiology

1. What is hypoxia? (AIM 8-1-2)

Hypoxia is a state of oxygen deficiency in the body sufficient to impair functions of the brain and other organs.

2. Where does hypoxia usually occur, and what symptoms should one expect? (AIM 8-1-2)

Although a determination in night vision occurs at a cabin pressure altitude as low as 5,000 feet, other significant effects of altitude hypoxia usually do not occur in the normal healthy pilot below 12,000 feet. From 12,000 feet to 15,000 feet of altitude, judgment, memory, alertness, coordination, and ability to make calculations are impaired, and headache, drowsiness, dizziness and either a sense of well-being or belligerence occur.

3. What factors can make a pilot more susceptible to hypoxia? (AIM 8-1-2)

a. Carbon monoxide inhaled in smoking or from exhaust fumes.
b. Anemia (lowered hemoglobin)
a. Certain medications
b. Small amounts of alcohol
c. Low doses of certain drugs (antihistamines, tranquilizers, sedatives, analgesics, etc.)
Also, extreme heat or cold, fever, and anxiety increase the body’s demand for oxygen, and hence its susceptibility to hypoxia.

4. How can hypoxia be avoided? (AIM 8-1-2)

Hypoxia is prevented by heading factors that reduce tolerance to altitude; by enriching the inspired air with oxygen from an appropriate oxygen system; and by maintaining a comfortable, safe cabin pressure altitude. For optimum protection, pilots are encouraged to use supplemental oxygen above 10,000 feet during the day and above 5,000 feet at night.

5. What is hyperventilation? (AIM 8-1-3)

Hyperventilation, or an abnormal increase in the volume of air breathed in and out of the lungs, can occur subconsciously when a stressful situation is encountered in flight. This results in a significant decrease in the carbon dioxide content of the blood. Carbon dioxide is needed to automatically regulate the breathing process.

6. What symptoms can a pilot expect from hyperventilation? (AIM 8-1-3)

As hyperventilation “blows off” excessive carbon dioxide from the body, a pilot can experience symptoms of light-headedness, suffocation, drowsiness, tingling in the extremities, and coolness, and react to them with even greater hyperventilation. Incapacitation can eventually result from un coordination, disorientation, and painful muscle spasms. Finally, unconsciousness can occur.

7. How can a hyperventilating condition be reversed? (AIM 8-1-3)

The symptoms of hyperventilation subside within a few minutes after the rate and depth of breathing are consciously brought back to normal. The buildup of carbon dioxide in the body can be hastened by controlled breathing in and out of a paper bag held over the nose and mouth.

8. What is “ear block”? (AIM 8-1-2)

As the aircraft cabin pressure decreases during ascent, the expanding air in the middle ear pushes the Eustachian tube open. The air then escapes down to the nasal passages and equalizes in pressure with the cabin pressure. But during descent, the pilot must periodically open the Eustachian tube to equalize pressure. Either an upper respiratory infection, such as a cold or sore throat, or a nasal allergic condition can produce enough congestion around the Eustachian tube to make equalization difficult. Consequently, the difference in pressure between the middle ear and aircraft cabin can build to a level that will hold the Eustachian tube closed, making equalization difficult if not impossible. An ear block produces severe pain and loss of hearing that can last from several hours to several days.

9. What action can be taken to prevent ear block from occurring in flight? (Aim 8-1-2)

Normally this can be accomplished by swallowing, yawning, tensing muscles in the throat or, if these don not work, by the combination of closing the mouth, pinching the nose closed and attempting to blow through the nostrils (Valsalva maneuver). It is also prevented by not flying with an upper respiratory infection or nasal allergic condition.

10. What is spatial disorientation? (FAA-H-8083-15)

Orientation is the awareness of the position of the aircraft and of oneself in relation to a specific reference point. Spatial disorientation specifically refers to the lack of orientation with regard to position in space and to other objects.

11. What causes spatial disorientation? (FAA-H-8083-15)

Orientation is maintained through the body’s sensory organs in three areas:
a. Visual : the eyes maintain visual orientation;
b. Vestibular: the motion sensing system in the inner ear maintains vestibular orientation;
c. Postural: the nerves in the skin, joins, and muscles of the body maintain postural orientation.
When human beings are in their natural environment, these three systems work well. However, when the human body is subjected to the forces of flight, these senses can provide misleading information resulting in disorientation.
12. What is the cause of motion sickness, and what are its symptoms? (FAA-P-8740-41)

Motion sickness is caused by continued stimulation of the tiny portion of the inner ear which controls the pilot’s sense of balance. The symptoms are progressive. First, the desire for food is lost. Then saliva collects in the mouth and the person begins to perspire freely. Eventually, he or she becomes nauseated and disoriented. The headaches and there may be a tendency to vomit. If the air sickness becomes severe enough, the pilot may become completely incapacitated.

13. What action should be taken if a pilot or passenger suffers from motion sickness? (FAA-P-8740-41)

If suffering from airsickness while piloting an aircraft, open up the air vents, loosen the clothing, use supplemental oxygen, and keep the eyes on a point outside the airplane. Avoid unnecessary head movements. Then cancel the flight and land as soon as possible.

14. What regulations apply, and what common sense should prevail concerning the use of alcohol? (AIM 8-1-1)

The regulations prohibit pilots from performing crewmember duties within 8 hours after drinking any alcoholic beverage or while under the influence of alcohol. However, due to the slow destruction of alcohol, a pilot may still be under influence 8 hours after drinking a moderate amount of alcohol. Therefore, an excellent rule is to allow at least 12 to 24 hours from “bottle to throttle”, depending on the amount of alcoholic beverage consumed.

15. What is carbon monoxide poisoning? (AIM 8-1-4)

Carbon monoxide is a colorless, odorless and tasteless gas contained in exhaust fumes. When breathed, even in minute quantities over a period of time, it can significantly reduce the ability of the blood to carry oxygen. Consequently, effects of hypoxia occur.

16. How does carbon monoxide poisoning occur, and what symptoms should a pilot be alert for? (AIM 8-1-4)

Most heaters in light aircraft work by air flowing over the manifold. Use of these heaters while exhaust fumes are escaping through manifold cracks and seals is responsible for several nonfatal and fatal aircraft accidents from carbon monoxide poisoning each year. A pilot who detects the odor of exhaust or experiences symptoms of headache, drowsiness, or dizziness while using the heater should suspect carbon monoxide poisoning.

17. What action should be taken if a pilot suspects carbon monoxide poisoning? (AIM 8-1-4)

A pilot who suspects this condition to exist should immediately shut off the heater and open all air vents. If symptoms are severe, or continue after landing, medical treatment should be sought.

18. What precautions should be taken before flight if you or your passengers have been involved in recent scuba diving activity? (AIM 8-1-2)

A pilot or passenger who intends to fly after scuba diving should allow the body sufficient time to rid itself of excess nitrogen absorbed during diving. If not, decompression sickness due to evolved gas can occur during exposure to higher altitudes and create a serious in-flight emergency.

The recommended waiting time before flight to cabin pressure altitudes of 8,000 feet or less is at least 12 hours after diving which has not required controlled ascent (non-decompression diving) and at least 24 hours after diving which has required controlled ascent (decompression diving). The waiting time before flight to cabin pressure altitudes above 8,000 feet should be at least 24 hours after any scuba diving.