5.3 Substances, Vision & Disorientation

Source: Sections 5.6 - 5.9

Substance Abuse (Alcohol)

Alcohol is selectively concentrated by the body into certain areas and can remain in the fluid of the inner ear even after all traces of alcohol in the blood have disappeared. This accounts for the difficulty in balance that is experienced in a hangover.

Impairment

Even small amounts of alcohol (0.05 percent) have been shown in simulators to reduce piloting skills.

Altitude Multiplier

The effect of alcohol and hypoxia is additive. At 6,000 ft ASL, the effect of one drink is equivalent to two drinks at sea level.

Metabolism

The body metabolizes alcohol at a fixed rate and no amount of coffee, medication, or oxygen will alter this rate.

The Rule

It is best to allow at least 24 hours between the last drink and take-off time.

Medications (Prescribed and Over the Counter)

It can be hazardous to take medicine in any form immediately before or while flying. Over-the-counter and herbal remedies (such as antihistamines, cough medicines, sleeping pills, and appetite suppressants) may cause drowsiness, decrease mental alertness, and seriously impair the judgement and co-ordination needed by the pilot.

Vision and Visual Scanning

VFR pilots fly in a “see-and-be-seen” world. Good vision is an important pilot tool, but it is affected by factors like hypoxia, carbon monoxide poisoning, alcohol, drugs, fatigue, smoking, and wearing the right prescription eyewear.

Scanning Technique

Visual scanning is an acquired skill. The eyes should be focused at a range that will ensure detection of traffic while there is still time to take avoiding action.

Empty-Field Myopia (Space Blindness)

This results from gazing at a featureless land or cloudscape. To avoid it, pilots must take an object on the horizon, focus on it, and then scan all sectors of the sky, refocusing as needed. Conscientious scanning of all sections of the sky, interspersed with brief interludes of focusing on distant objects, improves a pilot’s ability to detect distant aircraft.

Gaggle Flying

In gaggles, you must keep your eyes scanning constantly between the gliders close to you to maintain situational awareness and safe separation. Any pilot uncomfortable with gaggle flying should leave immediately. When conditions are very turbulent, separation should be increased to allow for unexpected maneuvers (for example, paraglider collapse).

Disorientation

Disorientation is an incorrect sense of position, attitude, or movement in relation to what is actually happening to the aircraft. On the ground, spatial orientation is sensed by a combination of vision, muscle sense (“seat of the pants”), and specialized organs in the inner ear (which sense linear and angular accelerations).

Vision is Strongest

Vision is the strongest of the orientation senses. In a whiteout or flying in cloud, it is sometimes impossible for the pilot to orient himself by reference to the horizon.

Inner Ear Illusions

Although the organs of balance in the inner ear give useful acceleration or turning information, they can also give rise to dangerous false information. Once a turn has been entered and is maintained at a steady rate, the sensation of turning will disappear. Upon recovering from the turn, a sensation of turning in the opposite direction may be encountered (which has been responsible for many accidents).

The Remedy

To avoid disorientation, do not lose sight of the ground.