Human Factors

M.D.H.C.H.O.S.E.N.S

• M – Motion Sickness

Caused by inner ear conflict and motion not matching visual cues.

Leads to nausea, dizziness, and fatigue.

• D – Drugs and Alcohol

Includes all impairing substances, even legal prescriptions and over-the-counter meds.

FAA: 8 hours bottle to throttle, 0.04% BAC limit. 12 hours for L3Harris.

Effects can linger longer than the hangover.

• H – Hypoxia (Four Types)

1. Hypoxic – Not enough oxygen in the air (e.g., high altitude).

2. Hypemic – Oxygen cannot bind to the blood (e.g., CO poisoning, anemia).

3. Stagnant – Poor circulation (e.g., G-forces, cold temperatures).

4. Histotoxic – Cells cannot use oxygen (e.g., alcohol, narcotics).

• C – Carbon Monoxide Poisoning

Odorless, colorless gas from exhaust leaks.

Binds to hemoglobin, preventing oxygen transport.

Symptoms: headache, drowsiness, confusion.

• H – Hyperventilation

Excessive breathing without exertion.

Reduces CO₂ → dizziness, tingling, and possible loss of consciousness.

Remedy: slow breathing, talk aloud, or breathe into a bag.

• O – Oxygen Requirements and Recommendations

12,500–14,000 ft MSL: Crew must use oxygen if exposure exceeds 30 minutes.

Above 14,000 ft MSL: Crew must use oxygen continuously.

Above 15,000 ft MSL: Oxygen must be available to passengers.

Recommendation: Use oxygen at night above 5,000 ft MSL because the rods in your eyes use more oxygen. 10,000 ft during the day.

• S – Sinus Blockage

Pressure changes during climb or descent cause sinus pain or blockage.

Can lead to vertigo, discomfort, or loss of concentration.

Avoid flying when congested.

• E – Ear Blockage (Barotrauma)

Similar to sinus blockage, affects the eustachian tubes.

May cause hearing loss, vertigo, or sharp pain.

Swallowing or yawning can help equalize pressure.

• N – Night Vision

Impaired by bright lights, oxygen deficiency, and fatigue.

Takes about 30 minutes to fully adapt.

Use red lights and avoid looking directly at bright sources.

• S – Scuba Diving Regulations

Wait 12 hours if flying below 8,000' and a controlled ascent was not required.

Wait 24 hours if flying above 8,000' or if a controlled ascent was required.

Flying too soon can lead to decompression sickness (the bends).

I.C.E.F.L.A.G.S

• I – Inversion Illusion

Cause: Abrupt change from climb to straight-and-level flight.

Illusion: The pilot feels as if the aircraft is tumbling backward.

Danger: May cause the pilot to push the nose down abruptly, risking a dive.

• C – Coriolis Illusion

Cause: A constant rate turn followed by an abrupt head movement (e.g., checking a chart).

Illusion: The sensation of turning, tumbling, or accelerating in multiple axes.

Danger: Can lead to disorientation and erratic control movements.

• E – Elevator Illusion

Cause: Updraft or downdraft (vertical acceleration).

Illusion: An upward acceleration feels like the nose is pitching up.

Danger: May lead the pilot to push the nose down, risking a descent.

• F – False Horizon

Cause: Misleading visual cues such as sloping cloud decks, city lights, or stars.

Illusion: The pilot aligns the aircraft with the false horizon, not the true one.

Danger: Results in unusual attitudes or banking unintentionally.

• L – Leans

Cause: Entering a banked turn too slowly for the semicircular canals to detect.

Illusion: The pilot believes the aircraft is level when it is actually banked.

Danger: When returning to true level flight, the pilot feels a lean and may re-bank.

• A – Autokinesis

Cause: Staring at a single stationary light against a dark background.

Illusion: The light appears to move on its own.

Danger: Pilot may maneuver the aircraft to follow this imaginary motion.

• G – Graveyard Spiral

Cause: Prolonged turn creates the illusion of not turning.

Illusion: When leveling the wings, the pilot feels a turn in the opposite direction.

Danger: The pilot may return to the original turn, losing altitude and tightening the spiral.

• S – Somatogravic Illusion

Cause: Rapid acceleration (e.g., during takeoff).

Illusion: The sensation of a nose-up pitch.

Danger: May cause the pilot to push the nose down, risking terrain impact, especially on takeoff.

F.R.A.G.

• F – Featureless Terrain

Occurs over dark, uniform, or textureless terrain such as snow, water, or open fields.

Illusion: Aircraft appears higher than it is.

Hazard: Pilot flies too low, risking an undershoot or controlled flight into terrain (CFIT).

• R – Runway Width and Slope Illusion

A narrow runway appears farther away → illusion of being higher → low approach.

A wide runway appears closer → illusion of being lower → high approach.

Upsloping runway appears steeper → illusion of being higher → low approach.

Downsloping runway appears shallower → illusion of being lower → high approach.

• A – Atmospheric Conditions (Clarity or Haze)

Hazy or foggy atmosphere causes illusion of greater distance → low approach.

Unusually clear air gives illusion of being closer → high approach.

• G – Ground Lighting

Lights along highways, buildings, or terrain mimic runway lighting.

May cause misalignment or landing on incorrect surface.