Human Factors Flashcards
What is hypoxia?
A state of oxygen deficiency in the body sufficient to impair functions of the brain and other organs.
What are the four forms of hypoxia?
1) Hypoxic - Any condition that interrupts the flow of O2 into the lungs. This is the type of hypoxia encountered at altitude due to the reduction of the partial pressure of O2.
2) Hypemic - Any condition that interferes with the ability of the blood to carry oxygen, such as anemia, bleeding, carbon monoxide, poisoning, smoking, certain prescription drugs.
3) Stagnant - Any situation that interferes with the normal circulation of the blood arriving to the cells. Heart failure, shock, and positive G-forces will bring about this condition.
4) Histotoxic - Any condition that interferes with the normal utilization of O2 in the cell. Alcohol, narcotics, and cyanide all can interfere with the cell’s ability to use the oxygen in support of metabolism.
Where does hypoxia usually occur and what symptoms should one expect?
Although a deterioration 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, judgement, memory, alertness, coordination, and ability to make calculations are impaired, and headache, drowsiness, dizziness, and either a sense of well-being or belligerence occur. Effects are worse above 15,000 feet.
What factors can make a pilot more susceptible to hypoxia?
The altitude at which significant effects of hypoxia occur can be lowered by a number of factors. Carbon monoxide inhaled in smoking or from exhaust fumes, lowered hemoglobin (anemia), and certain medications can reduce the oxygen-carrying capacity of the blood. Small amounts of alcohol and low doses of certain drugs, such as antihistamines, tranquilizers, sedatives, and analgesics can, through their depressant action, render the brain much more susceptible to hypoxia. Extreme heat and cold, fever, and anxiety increase the body’s demand for oxygen and hence its susceptibility to hypoxia.
How can hypoxia be avoided?
By heeding 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.
What is hyperventilation?
An abnormal increase in the volume of air breathed in and out of the lungs. This 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.
What symptoms can a pilot expect from hyperventilation?
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 even result from uncoordination, disorientation, and painful muscle spasms. Unconsciousness can occur.
How can a hyperventilating condition be reversed?
Symptoms 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.
What is carbon monoxide poisoning?
Carbon monoxide is a colorless, odorless, and tasteless gas contained in exhaust fumes. When inhaled, even in minute quantities over a period of time, it can significantly reduce the ability of the blood to carry oxygen. Effects of hypoxia occur.
How does carbon monoxide poisoning occur and what symptoms should a pilot be alert for?
Most heaters in light aircraft work by air flowing over the manifold. The use of these heaters while exhaust fumes are escaping through manifold cracks and seals is responsible every year for several nonfatal and fatal aircraft accidents from carbon monoxide poisoning. 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.
What action should be taken if a pilot suspects carbon monoxide poisoning?
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.
What is the cause of motion sickness and what are its symptoms?
Motion sickness is caused by continued stimulation of the inner ear, which controls the sense of balance. The symptoms are progressive and include loss of appetite, saliva collecting in the mouth, perspiration, nausea, disorientation, headaches, and possible vomiting. The pilot may become incapacitated if it becomes severe enough.
What action should be taken if a pilot or his/her passenger suffers from motion sickness?
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. Terminate the flight and land as soon as possible.
What is ear block?
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, like 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 days.
What action can be taken to prevent ear block from occurring in flight?
Normally this can be accomplished by swallowing, yawning, tensing muscles in the throat or, if these do not work, by the combination of closing the mouth, pinching the nose closed and attempting to blow through the nostrils. It’s also prevented by not flying with an upper respiratory infection or nasal allergic condition.
What regulations apply and what common sense should prevail concerning the use of alcohol?
Pilots are prohibited from flying within 8 hours after drinking any alcoholic beverage, while under the influence of alcohol, or having a .04% or more alcohol in the blood.
For a pilot who has been taking an over-the-counter cold medication, how do the various environmental factors the pilot is exposed to inflight affect the drug’s physiological impact on the pilot?
Drugs that cause no apparent side effects on the ground can create serious problems at relatively low altitudes. Even at typical general aviation altitudes, the changes in concentrations of atmospheric gases in the blood can enhance the effects of seemingly innocuous drugs and result in impaired judgement, decision-making, and performance.
What regulations apply and what common sense should prevail concerning the use of drugs and medication?
Pilot performance can be seriously degraded by both prescribed and OTC medications, as well as by the medical conditions for which they are taken. The regulations prohibit pilots from performing crewmember duties while using any medication that affect the faculties in any way contrary to safety. The safest rule is not to fly while taking any medication, unless approved to do so by the FAA.
Discuss the effects of nitrogen excesses during scuba diving upon a pilot or passenger in flight.
A person 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 low altitude and create a serious inflight emergency. The recommended waiting times before flight are:
Flight altitudes up to 8,000 feet
1) Wait at least 12 hours after diving which has not required a controlled ascent
2) Wait at least 24 hours after diving which has required controlled ascent.
Flight altitudes above 8,000 feet
1) Wait at least 24 hours after any scuba dive.
You recently experienced a bad cold and were treated by your personal physician. You continue to take the medications your physician prescribed, but feel much better. Can you resume flying on your current medical or must you first see an FAA AME?
Anytime you experience an illness or an injury that you feel may affect your ability to safely fly an aircraft, you must self-ground until you feel better. 12 CFR 61.53 requires that all pilots voluntarily self-ground anytime:
1) They know or have reason to know of any medical condition that would make them unable to meet the requirements for the medical certificate necessary for the pilot operation.
2) They are taking medication or receiving other treatment for a medical condition that results in them being unable to meet the requirements for the medical certificate necessary for the pilot operation.
If in doubt, call your AME.
Can you operate an aircraft while taking an OTC medication for an on-going condition?
Self-medication or taking medication in any form while you are flying can be extremely hazardous. Even simple OTC remedies may seriously impair the judgement and coordination needed while flying. The safest rule is to take no medicine while flying, except with the advice of your AME.
Define the term single-pilot resource management.
SRM is the art and science of managing all the resources available to a single pilot to ensure that the successful outcome of the flight is never in doubt. SRM helps pilots learn to execute methods of gathering information, analyzing it, and making decisions.
What are examples of the skills necessary for effective SRM?
SRM includes the concepts of aeronautical decision making, risk management, task management, automation management, controlled flight into terrain awareness, and situational awareness.
What practical application provides a pilot with an effective method to practice SRM?
The “5P” checklist consists of
1) The Plan
2) The Plane
3) The Pilot
4) The Passengers
5) The Programming
Based on the idea that the pilot has essentially five variables that impact his or her environment and that can cause the pilot to make a single critical decision or several less critical decisions that when added together can create a critical outcome.
Explain the use of the 5P model to assess risk associated with each of the five factors.
Plan - Weather, route, publications, ATC reroutes/delays, fuel onboard/remaining.
Plane - Mechanical status, automation status, database currency, backup systems.
Pilot - Illness, medication, stress, alcohol, fatigue, eating
Passengers - Pilots/non-pilots, nervous or quiet, experienced or new, business or pleasure
Programming - Autopilot, GPS, MFD/PFD, anticipate likely reroutes/clearances, questions to ask
What is the use of the 5P checklist recommended?
The 5P concept relies on the pilot to adopt a scheduled review of the critical variables at points in the flight where decisions are most likely to be effective. These key decision points include preflight, pre-takeoff, hourly or at the midpoint of the flight, pre-descent, and just prior to the final approach fix. They also should be used anytime an emergency situation arises.
Define the term aeronautical decision making.
ADM is a systematic approach to the mental process used by aircraft pilots to consistently determine the best course of action in response to a given set of circumstances.
