ACS Study Book Task H: Human Factors

Flashcards covering human factors, types of hypoxia, aeromedical issues, sensory illusions, and spatial disorientation based on Task H study notes.

What is hypoxia and when does it occur?

Hypoxia is defined as reduced oxygen or not enough oxygen, occurring when the body's tissues are NOT getting enough oxygen and are deprived of an adequate oxygen supply.

What is Hypoxic Hypoxia and what triggers it?

Hypoxic Hypoxia is caused by insufficient oxygen available to the body as a whole. Its trigger is high altitude, where lower partial air pressure causes less densely packed air molecules, equating to fewer oxygen molecules per breath.

What is Hypemic Hypoxia and how does carbon monoxide cause it?

Hypemic Hypoxia is caused by oxygen deficiency in the blood (not a lack of inhaled oxygen). Hemoglobin is unable to bind to oxygen molecules because carbon monoxide molecules are 200 times more attracted to hemoglobin than oxygen, taking up oxygen's binding spot chemically.

What is Stagnant Hypoxia and what are its triggers?

Stagnant Hypoxia occurs when oxygen-rich blood in the lungs is not moving to the tissues that need it. Triggers include excessive G's, cold temperature (causing less circulation), blood vessel disease, heart arrest, shock, or a sudden change in posture.

What is Histotoxic Hypoxia and what triggers it?

Histotoxic Hypoxia occurs when oxygen is reaching the cells that need it, but the cells/tissues are unable to make use of it. Triggers include alcohol, drugs, narcotics, and poisons.

What are the 10 symptoms of hypoxia listed in the lecture notes?

1) Cyanosis (blue fingernails and tips), 2) Headache, 3) Decreased response to stimuli and increased reaction time, 4) Impaired judgement, 5) Euphoria, 6) Visual impairment, 7) Drowsiness, 8) Light-headed / dizzy sensation, 9) Tingling in fingers/toes, and 10) Numbness.

What are the recovery steps for hypoxia during flight?

1) Set oxygen mask to 100% immediately, 2) Descend (emergency) to 10,000 ft MSL or lower if able, 3) Open air vents and shut off air heaters if CO poisoning is suspected, and 4) Possibly land as soon as possible.

What is Time of Useful Consciousness (TUC) and what are its durations at 45,000 ft, 35,000 ft, and 25,000 ft?

TUC is the time a pilot has from the moment oxygen deprivation begins until they are no longer able to take proper corrective action. Duration at 45,000 feet is 9–15 seconds; at 35,000 feet is 30–60 seconds; and at 25,000 feet is 3–5 minutes.

What is hyperventilation, and how can it be cured or prevented?

Hyperventilation is the excessive loss of CO2 in the blood caused by an excessive rate and depth of respiration. Cure/Prevention: 1) Breathe normally, 2) Breathe into a paper bag, and 3) Talk aloud.

How do middle ear blockages occur during rapid climbs and rapid descents?

During rapid climbs, outside air pressure (OAP) drops, making middle ear pressure higher than OAP, causing air to expand and shoot out through the Eustachian tube. During rapid descents, OAP increases rapidly, leaving lower-pressure air stuck in the middle ear. Descents can be fixed by swallowing, yawning, or using the Valsalva technique.

What causes sinus blockage and what symptom does it produce?

Sinus blockage is caused by congestion from sinusitis, nasal allergies, or colds plugging the small openings to the nasal passage, preventing pressure equalization with OAP and causing severe stabbing-like pain.

What is Spatial Disorientation and which three integrated systems determine orientation?

Spatial Disorientation is the lack of orientation with regards to the position, altitude, or movement of the airplane in space. The three integrated systems are the Vestibular System (inner ear), Somatosensory System, and Visual System.

How do the semicircular canals and otolith organs in the Vestibular System sense movement?

The three semicircular canals per ear contain fluid that moves when turning, tilting, or pitching, deflecting hairs to sense motion during acceleration. Hairs in the otolith organs signal pitch changes during linear acceleration and deceleration.

How does the Somatosensory System contribute to sensing position?

Nerves in the skin, muscles, and joints, along with hearing, send signals to the brain that are interpreted as position in relation to Earth's gravitational pull.

What causes 'The Leans' illusion?

The Leans occurs when an unnoticed entry into a turn occurs at a rate of $2^\bullet$ or less per second (under the detection threshold of semicircular canals). When the pilot realizes the turn from instruments and rapidly banks back to level flight, the vestibular system interprets the return as an over-bank in the opposite direction, prompting the pilot to bank back into the original turn.

What is the Graveyard Spiral illusion and how is it prevented?

While in a constant, coordinated, and prolonged turn, a pilot loses the sensation of turning. Returning to level flight causes the sensation of turning in the opposite direction, prompting the pilot to re-enter the original turn. As altitude drops, pulling back on the yoke tightens the turn radius and increases descent speed. Prevention: instrument and illusion awareness, watching altitude, speed, and bank turns, and trusting instruments.

What causes the Coriolis Illusion?

The Coriolis Illusion is caused by rapid head movement in a different plane (pitch, roll, or yaw) after being in a prolonged turn or state of flight, causing fluid speed changes in more than one semicircular canal and producing a tumbling sensation.

What is the Somatogravic Illusion?

The Somatogravic Illusion occurs during rapid acceleration or deceleration, which stimulates the otolith organs as if the head were tilted backward or forward, causing the pilot to perceive the acceleration or deceleration as a climb or descent attitude.

What is the Inversion Illusion?

The Inversion Illusion occurs when an abrupt change from a climb to straight-and-level flight stimulates the otolith organs, creating the illusion of tumbling backwards.

What is the Elevator Illusion?

The Elevator Illusion occurs when an abrupt upward vertical acceleration (such as from an updraft) stimulates the otolith organs to perceive a climb, causing the pilot to push the nose down too low. Conversely, downdrafts cause perception of a nose-low acceleration, prompting recovery with a nose-high attitude.