Human Factors (ACS) Flashcards
(Human Factors)
What is Hypoxia?
Not enough oxygen. There are 4 forms of hypoxia that are encountered in flight.
-Hypoxic Hypoxia: when your body is working just fine but its not getting enough oxygen. In flight this is often caused by the lack of constant pressure at a high altitude.
-Hypemic Hypoxia: Hypemic hypoxia occurs when the blood is unable to carry sufficient oxygen. The most common causes of hypemic hypoxia are anemia and carbon monoxide poisoning.
-Stagnant Hypoxia: occurs when the blood is stagnant or somehow is not being circulated around the body properly. It can also be caused locally in the body wherein parts of the body are not receiving blood flow. Sitting for long periods of time resulting in a leg falling asleep is a good example of stagnant hypoxia. It can also result from low blood pressure.
-Histotoxic Hypoxia: this happens when oxygen is being supplied just fine by the body but the tissues themselves are unable to make use of it. This can be caused by drugs, alcohol, or poison.
(Human Factors)
What are some of the signs of Hypoxia?
The effects are subtle and when true symptoms start to show there is a good chance that it is too late to do anything about it.
-Euphoria and a carefree attitude.
-Drowsiness, headache, impaired judgement, slow reaction time, visual problems, a blue tinge to the finger nails or lips, and dizziness.
(Human Factors)
What are the supplemental oxygen regulations as they apply to flight crew and other occupants?
Hypoxia affects everyone’s senses differently. Due to different lifestyles, body types, and ages. Extended flight at high altitudes without supplemental oxygen will seriously affect your ability to fly.
FAR 91.211 is the Oxygen supplementation FAR.
-if the pressure altitude is above 12,500 up to and including 14,000’ and the aircraft is within that altitude range for 30 minutes or more the minimum flight crew needs to be on supplemental oxygen.
-If the aircraft is over 14,000’ MSL the minimum flight crew needs to be on oxygen for the entire time.
-If the cabin altitude is over 15,000’ MSL each occupant must be provided with supplemental oxygen. The occupants aren’t required to use the oxygen, but it needs to be available.
FAA recommends using oxygen at lower altitudes. AIM 1-2
above 10,000’ MSL during the day
above 5,000’ MSL during the night
Night vision is one of the first things that break down in a hypoxic event.
(Human Factors)
What is hyper ventilation?
when an excessive rate of breathing causes the body to get rid of too much carbon dioxide.
(Human Factors)
What is the danger of flying with an ear infection or sinus problems?
One side of the ear is connected to the outside world via the eustation tube which opens up into the back of the throat. The other side of the middle ear is blocked by the ear drum. If the middle ear or the eustation tube is blocked by swelling or infection the pressure in the ear cant equalize the ambient pressure. As the aircraft climbs and the pressure decreases this pressure differential can cause some serious pain. Sometimes to the degree it will incapacitate the pilot.
(Human Factors)
What is spatial disorientation?
visual system, somatosensory system (nerves), and vestibular system (inner ear) send signals to the brain to establish balance and other things.
Spatial disorientation is a pilot’s misunderstanding of their aircraft’s position, motion, or attitude in relation to the Earth’s surface.
For example, you feel that you’re turning when, in fact, your wings are perfectly level.
(Human Factors)
What are the forms of spatial disorientation that you may encounter in flight?
Inversion, Coriolis, Elevator, False horizon, Leans, Autokinesis, Graveyard Spiral, Somatogravic
ICEFLAGS:
Inversion
Coriolis
Elevator
False horizon
Leans
Autokinesis
Graveyard spiral
Somatogravic
(Human Factors)
What is the Inversion illusion?
The inversion illusion happens when a pilot quickly transitions from a climb to straight-and-level. In other words, they pitch the nose down quickly, making them feel like they’re tumbling backward.
Because the pilot feels that they are tumbling backward, they may pitch the nose down even further, intensifying the illusion and leading to a dangerous low-nose attitude.
The inversion illusion results from some complex interplay between your inner ear and brain.
Inside your ears, there are three semicircular canals filled with fluid, which move when your head moves. These canals are at right angles to each other, and each one detects a different type of movement: up and down, side to side, and tilting from one side to the other.
During an abrupt change from climbing to level flight, the fluid in the vertical canals of your inner ear continues to move. Your brain misinterprets this as a sensation of still climbing, making you feel like you’re tumbling backward.
This false perception of your body’s position – thinking you’re in a climb when you’re not – leads to the inversion illusion. It’s your brain playing tricks on you by interpreting the signals from your inner ear incorrectly.
That’s why it’s crucial to trust your instruments over your senses – they aren’t subject to these physiological illusions!
How to Prevent the Inversion Illusion
Preventing the inversion illusion boils down to one key factor: managing your aircraft’s movements smoothly and gradually.
By transitioning more gently between different stages of flight, you can help your body better adjust to the changes in motion, reducing the chance of misinterpretation.
(Human Factors)
What is the Coriolis Illusion?
Imagine you’re turning steadily in one direction for a while (say, to the left). Your body has gotten used to this motion, but then, you suddenly move your head down to check a chart or up to look at an overhead panel.
Whoa!
Suddenly, it feels like you’re tumbling or rotating in all sorts of directions, not just the gentle left turn you initiated.
Welcome to the dizzying world of the Coriolis Illusion.
The culprit?
Those semicircular canals in your ears again.
When you’re turning for a while, the fluid in your ear canals starts to move at the same speed as the canal walls, tricking your brain into thinking you’ve stopped turning.
Then, when you move your head suddenly, the fluid moves across multiple canals, sending your brain mixed signals and causing you to feel like you’re tumbling head over heels.
How to Prevent the Coriolis Illusion
So how do you keep the Coriolis Illusion in check? Keep your head movements slow and steady during turns, particularly when flying on instruments.
(Human Factors)
What is the Elevator Illusion?
Picture this: you’re flying along in less-than-perfect visibility when suddenly, you hit an updraft.
Your aircraft gets a quick boost, and your inner ear tells your brain that you’re in a climb. However, you’re not climbing – your altitude hasn’t changed.
This false sensation can prompt you to push the aircraft’s nose down, potentially initiating a descent.
This illusion gets its name because it feels a lot like the momentary floating sensation you get when an elevator starts moving upward rapidly.
How to Prevent the Elevator Illusion
The solution to the Elevator Illusion?
Trust your instruments! They’ll give you an accurate picture of your altitude and climb rate, not your gut feeling.
Always cross-check your instrument readings before taking corrective action based on what your senses are telling you.
(Human Factors)
What is the False Horizon Illusion?
This illusion is a master of disguise and can really trip you up if you’re not careful.
Let’s set the scene.
You’re flying at night or in poor visibility conditions with no distinct horizon. There may be city lights below, stars above, or you’re over water with no discernible landmarks.
Suddenly, your brain spots something, a cloud bank, a line of lights, or a pattern of stars, and decides, “That’s the horizon!”
Spoiler alert: It’s not.
This misperception can lead to incorrect control inputs as you adjust your aircraft’s attitude based on a fictitious horizon.
How to Prevent the False Horizon Illusion
The antidote to the False Horizon Illusion? You’ve got it – rely on your instruments! They don’t care about cloud banks, city lights, or star patterns.
To further arm yourself against this illusion, enhance your understanding of your aircraft’s attitude indicator. Learn to interpret it correctly and trust it over your senses.
(Human Factors)
What is the Leans Illusion?
This one’s a subtle trickster, so get ready.
Say you’ve unknowingly entered a slow, gentle bank. You correct the bank, but it is so gradual your inner ear doesn’t detect it.
Your senses still believe you’re straight and level, so when you level out, it feels like you’re banking in the opposite direction.
Your instinct may be to return to the original bank to ‘level’ the aircraft, thus creating a continuous banked turn.
This deceptive sensation is aptly named the Leans.
It’s called the leans because you feel like you’re leaning to one side, even though you’re perfectly level.
How to Prevent The Leans
To avoid the leans, apart from trusting your instruments, you should avoid slow, gradual turns.
You should always use smooth inputs, but try to avoid “creeping” into a turn.
Additionally, keep cross-checking your instruments to avoid inadvertently turning.
(Human Factors)
What is the Autokinesis Illusion?
Imagine you’re flying at night, and there’s a stationary light in the distance. If you fix your gaze on this light for more than a few seconds, it can start to move – on its own!
Well, not really.
The light isn’t moving at all, but your brain insists it is. This perception of movement where there is none is the autokinesis illusion.
This illusion can lead to misjudging the movement of other aircraft at night. You might think another airplane is moving when it’s not, or you might misinterpret its speed and direction. And if you think a star or a far-off light is another aircraft, you might find yourself chasing phantoms across the night sky!
How to Prevent the Autokinesis Illusion
The countermeasure to autokinesis? Don’t stare at a single point of light for too long. Keep your eyes moving and scan different areas of the sky.
(Human Factors)
What is the Graveyard Spiral Illusion?
You’ve entered a gentle turn that has gone unnoticed. Because your inner ear adjusts to the turn, it stops sending turn signals to your brain.
When you finally notice and correct the turn, it feels like you’ve started turning in the opposite direction. In reaction to this false perception, you re-enter the original turn.
Here’s where things get dangerous.
As you continue this unnoticed turn, your aircraft starts to lose altitude (because the nose will drop during a turn).
If you pull back on the yoke without leveling the wings, you’ll tighten the turn and descend even faster.
This deadly descent is what we call a graveyard spiral. Out of all eight illusions, the graveyard spiral poses the greatest danger to pilots.
How to Prevent the Graveyard Spiral
Cross-checking your instruments is the best way to avoid entering the graveyard spiral.
A quick identification and correction of the bank is all you need to avoid the graveyard spiral altogether.
(Human Factors)
What is the Somatogravic Illusion?
Let’s say you increase power to increase speed at night or in IMC (Instrument Meteorological Conditions).
The rapid acceleration pushes you back in your seat, giving a sensation similar to pitching up.
Your brain, ever so deceptive, interprets this feeling as a climb.
You might inadvertently push the nose down to counter this, causing a dangerous descent.
Welcome to the somatogravic illusion.
The same can happen in reverse during deceleration. The reduced forward pressure can feel like a downward pitch, potentially causing an unnecessary climb.
How to Prevent the Somatogravic Illusion
A good old instrument scan will go a long way in preventing the somatogravic illusion.
Additionally, try to avoid unnecessary rapid increases or decreases in airspeed.
