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Questions and Answers
What happens to the volume of a gas as pressure increases, according to Boyle's Law?
What happens to the volume of a gas as pressure increases, according to Boyle's Law?
Which type of hypoxia is most commonly caused by inadequate ambient oxygen during flight?
Which type of hypoxia is most commonly caused by inadequate ambient oxygen during flight?
According to Gay-Lussac’s Law, what happens to the pressure of a gas at constant volume as its temperature increases?
According to Gay-Lussac’s Law, what happens to the pressure of a gas at constant volume as its temperature increases?
Which condition is NOT associated with Decompression Sickness (DCS)?
Which condition is NOT associated with Decompression Sickness (DCS)?
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What effect does nicotine have on flight safety?
What effect does nicotine have on flight safety?
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What is the recommended maximum time for a crew member to consume alcohol before acting as a crew member?
What is the recommended maximum time for a crew member to consume alcohol before acting as a crew member?
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At what altitude must supplemental oxygen be worn by the pilot for the entire duration at altitude?
At what altitude must supplemental oxygen be worn by the pilot for the entire duration at altitude?
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What is a common symptom of hypoxic hypoxia?
What is a common symptom of hypoxic hypoxia?
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What physiological phenomenon does Henry's Law describe?
What physiological phenomenon does Henry's Law describe?
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What is the Time of Useful Consciousness (TUC) at an altitude of 30,000 feet after a slow loss of pressure?
What is the Time of Useful Consciousness (TUC) at an altitude of 30,000 feet after a slow loss of pressure?
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Which of the following best describes the term Barodontalgia?
Which of the following best describes the term Barodontalgia?
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Which condition can significantly increase susceptibility to flicker vertigo in aircrew members?
Which condition can significantly increase susceptibility to flicker vertigo in aircrew members?
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Under what conditions might a flight crew feel delayed symptoms of hyperventilation?
Under what conditions might a flight crew feel delayed symptoms of hyperventilation?
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If a pilot is incoherent and unable to maintain control at altitude, what stage of hypoxia are they likely experiencing?
If a pilot is incoherent and unable to maintain control at altitude, what stage of hypoxia are they likely experiencing?
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What is the duration of TUC when experiencing rapid depressurization at 30,000 feet?
What is the duration of TUC when experiencing rapid depressurization at 30,000 feet?
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Which altitude requires supplemental oxygen after 30 minutes of flight?
Which altitude requires supplemental oxygen after 30 minutes of flight?
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What physiological effect can occur due to a slow loss of cabin pressure at high altitude?
What physiological effect can occur due to a slow loss of cabin pressure at high altitude?
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What is a common psychosocial stressor that could impact aircrew performance?
What is a common psychosocial stressor that could impact aircrew performance?
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What type of flight scenario might require an immediate cabin descent?
What type of flight scenario might require an immediate cabin descent?
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Which factor is least likely to cause disturbance in a pilot's performance under hypoxia?
Which factor is least likely to cause disturbance in a pilot's performance under hypoxia?
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What is the most likely physiological effect when ascending rapidly during flight?
What is the most likely physiological effect when ascending rapidly during flight?
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Which type of hypoxia results from the blood's reduced capacity to carry oxygen?
Which type of hypoxia results from the blood's reduced capacity to carry oxygen?
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What law describes the relationship where the volume of a gas decreases as pressure increases?
What law describes the relationship where the volume of a gas decreases as pressure increases?
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Which scenario is most directly associated with the effects of nicotine in flight?
Which scenario is most directly associated with the effects of nicotine in flight?
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What can be a consequence of vibration during rotor wing transport?
What can be a consequence of vibration during rotor wing transport?
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What is the result of applying Henry's Law in aviation physiology?
What is the result of applying Henry's Law in aviation physiology?
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What is a primary recommendation for managing fatigue in aircrew?
What is a primary recommendation for managing fatigue in aircrew?
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Which of the following conditions contributes to stagnant hypoxia?
Which of the following conditions contributes to stagnant hypoxia?
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What stage of hypoxia occurs when oxygen saturation drops to between 70-79%?
What stage of hypoxia occurs when oxygen saturation drops to between 70-79%?
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What legal requirement limits the consumption of alcohol for crew members?
What legal requirement limits the consumption of alcohol for crew members?
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What is the time duration after which supplemental oxygen must be worn at an altitude above 12,500 MSL?
What is the time duration after which supplemental oxygen must be worn at an altitude above 12,500 MSL?
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At which altitude must pilots use supplemental oxygen for the entire duration of their flight if they make up the required minimum flight crew?
At which altitude must pilots use supplemental oxygen for the entire duration of their flight if they make up the required minimum flight crew?
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What is the typical Time of Useful Consciousness (TUC) after a rapid loss of cabin pressure at 30,000 feet?
What is the typical Time of Useful Consciousness (TUC) after a rapid loss of cabin pressure at 30,000 feet?
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Which of the following factors could make an aircrew member more prone to experience flicker vertigo?
Which of the following factors could make an aircrew member more prone to experience flicker vertigo?
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What is the most likely stage of hypoxia if a pilot is incoherent and cannot maintain control of the aircraft?
What is the most likely stage of hypoxia if a pilot is incoherent and cannot maintain control of the aircraft?
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What effect does a slow loss of cabin pressure at 30,000 feet have on a pilot's functional ability?
What effect does a slow loss of cabin pressure at 30,000 feet have on a pilot's functional ability?
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If a pilot is experiencing significant psychosocial stress, what could this potentially lead to during flight?
If a pilot is experiencing significant psychosocial stress, what could this potentially lead to during flight?
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Which scenario would most likely necessitate an emergency cabin descent?
Which scenario would most likely necessitate an emergency cabin descent?
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What specific characteristic of nicotene's effect on aircrew should be recognized?
What specific characteristic of nicotene's effect on aircrew should be recognized?
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When experiencing an aircraft cabin depressurization, how long does a pilot typically have to respond before significant impairment occurs under rapid depressurization?
When experiencing an aircraft cabin depressurization, how long does a pilot typically have to respond before significant impairment occurs under rapid depressurization?
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Study Notes
Dalton’s Law
- Describes the total pressure of a mixture of gases
Boyle’s Law
- Volume is inversely proportional to pressure at a given temperature
- Volume decreases as pressure increases
- Volume increases as pressure decreases (altitude)
Effects of Boyle’s Law (Trapped Gas)
- Gastrointestinal distress
- Ear pain: expanding pressure in middle ear
- Sinus pain: trapped gases during flight
- Barodontalgia
- ETT cuff pressure
Charles’s Law
- Volume is proportional to temperature at a given pressure
- Gas expands when heated
Gay-Lussac’s Law
- Pressure is directly proportional to temperature at a constant volume
- For every 1000ft of altitude, the temperature decreases 1ºC (or 330 ft for 1ºF)
Henry’s Law
- The amount of gas dissolved in a liquid is directly proportional to the gas’s partial pressure
Decompression Sickness
- Rapid ascent can cause nitrogen bubbles to form in tissues and blood
- Type I DCS: “The Bends”
- Type II DCS: “The Chokes”
HYPOXIA: TYPES AND STAGES
- Inadequate oxygen in the body due to various factors
Hypoxic Hypoxia
- Most common cause in flight (aka: altitude hypoxia)
- Inadequate ambient oxygen
Hypemic Hypoxia
- Reduced blood oxygen carrying capacity
- Carbon monoxide reduces hemoglobin’s ability to carry O2
Stagnant Hypoxia
- Inadequate blood flow leads to insufficient tissue oxygenation
- Shock states cause sluggish blood flow
Histotoxic Hypoxia
- Cells cannot use oxygen
- Cyanide poisoning
Stages of Hypoxia
- Indifferent (90-98%)
- Compensatory (80-89%)
- Disturbance (70-79%)
- Critical (60-69%)
STRESSORS OF AIR TRANSPORT
- Factors that contribute to fatigue and discomfort during flight
Self-Imposed Stressors
- Medications
- Supplements
- Energy Drinks
- Tobacco, nicotine
- Alcohol
Effects of Nicotine
- Experiences effects of hypoxia at lower altitudes
- Increased CO level
- Nicotine affects vision
- Reduced night vision
- 40% reduction in night vision at 5,000’ MSL
Alcohol Consumption
- 14 CFR 91.17 prohibits crew members from:
- Acting as crew within 8 hours after alcohol consumption
- Flying under the influence of alcohol
Fatigue
- Circadian effects
- Physical fatigue
- Recommendations:
- Breaks of 15 min every 2 hours
- 24 hours of uninterrupted rest after night shifts
- Schedule off days in periods of at least three days
- Exercise, diet, no smoking
Vibration
- Rotor wing transport causes whole-body vibration
- Motion sickness
- Hyperventilation
- Headache
- Decreased visual acuity
- May cause acceleration of spine disorders
- Causes localized leg, buttocks, and back pain with numbness and muscle spasms
Flicker Vertigo
- Confuses the vestibular system
- May result in spatial disorientation leading to inaccurate perceptions of altitude and speed
Pressurized vs.Unpressurized Cabins
- CFR 91.211: Supplemental oxygen must be worn by pilots:
- At >12,500 MSL for >30 min
- At >14,000 MSL during the entire time at altitude for “required minimum flight crew”
Physiologic Zones
- Time of Useful Consciousness (TUC)
- Time between oxygen interruption and inability to perform flying duties
- Slow loss of pressure at 30,000’ altitude: 90 seconds
- Rapid depressurization at 30,000’ altitude: 45 seconds
Dalton’s Law
- The total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases.
- This law helps explain the concept of hypoxic hypoxia, where reduced partial pressure of oxygen at altitude can cause oxygen deficiency.
Boyle’s Law
- For a given temperature, the volume of a gas is inversely proportional to the pressure.
- As pressure increases, volume decreases.
- Conversely, as pressure decreases (like at higher altitudes), volume increases.
Effects of Boyle's Law (Trapped Gas)
- Can cause gastrointestinal distress, ear pain (expanding pressure in the middle ear), sinus pain (trapped gases during flight), and barodontalgia (tooth pain due to expanding pressure in dental cavities).
Charles's Law
- For a given pressure, the volume of a gas is proportional to the absolute temperature.
- As temperature increases, the volume of gas expands.
Gay-Lussac’s Law
- The pressure of a fixed mass of gas at constant volume is directly proportional to its absolute temperature.
- This law helps explain the decrease in temperature with increasing altitude as the air pressure decreases.
Henry's Law
- The amount of a given gas dissolved in a liquid is directly proportional to the partial pressure of the gas in contact with the liquid.
- This explains how decompression sickness occurs due to the release of nitrogen gas dissolved in the body's tissues and blood at lower pressures (higher altitudes).
Decompression Sickness
- Rapid ascent can cause a rapid decrease in pressure, leading to the formation of nitrogen bubbles in the tissues and blood.
- Type I DCS (The Bends): nitrogen bubbles in the joints and muscles.
- Type II DCS (The Chokes): nitrogen bubbles in the lungs causing breathing difficulties.
Hypoxic Hypoxia
- The most common cause of hypoxia in flight.
- Occurs due to insufficient oxygen in the air breathed at high altitudes.
Hypemic Hypoxia
- Reduced capacity of the blood to carry oxygen.
- Carbon monoxide poisoning reduces hemoglobin's ability to bind oxygen.
Stagnant Hypoxia
- Inadequate blood flow to tissues resulting in insufficient oxygenation.
- Can occur during shock states.
Histotoxic Hypoxia
- The cells are unable to use oxygen due to cellular damage.
- Can be caused by cyanide poisoning.
Stages of Hypoxia
- Indifferent: (90-98% oxygen saturation) - no noticeable symptoms.
- Compensatory: (80-89% oxygen saturation) - increased heart rate, respiration, and mental function.
- Disturbance: (70-79% oxygen saturation) - impaired judgment, coordination, vision, and hearing.
- Critical: (60-69% oxygen saturation) - loss of consciousness, and death if not reversed.
Self-Imposed Stressors
- Medications, supplements, energy drinks, nicotine, alcohol, and caffeine can worsen the effects of hypoxia and other stressors.
Effects of Nicotine
- Increases the effects of hypoxia at lower altitudes.
- Increases carbon monoxide levels in the blood.
- Impairs vision, especially at night, reducing night vision by 40% at 5,000 feet.
Alcohol Consumption
- As per 14 CFR 91.17, no crew member can act as a crew member of a civil aircraft:
- Within 8 hours after consuming any alcoholic beverage.
- While under the influence of alcohol.
Fatigue
- Circadian effects, physical fatigue, and workload contribute to fatigue in flight.
Recommendations for Managing Fatigue
- Take breaks of 15 minutes every 2 hours.
- Schedule 24 hours of uninterrupted rest after night shifts.
- Schedule off days in periods of at least three days.
- Maintain a healthy diet, exercise regularly, and avoid smoking.
Vibration
- Rotorcraft transport causes whole-body vibration.
Effects of Vibration:
- Motion sickness.
- Hyperventilation.
- Headache.
- Decreased visual acuity.
- Acceleration of spine disorders.
- Localized leg, buttocks, and back pain, numbness, and muscle spasms.
Flicker Vertigo
- The rapid flashing of lights or patterns confuses the vestibular system (balance system).
- Can lead to spatial disorientation, inaccurate perceptions of altitude and speed, and impaired flight control.
Pressurized vs. Unpressurized Cabins
- CFR 91.211: Supplementary oxygen is required for pilots:
- At altitudes above 12,500 MSL for more than 30 minutes.
- At altitudes above 14,000 MSL during the entire time at altitude for the “required minimum flight crew”.
Time of Useful Consciousness (TUC)
- The time between the interruption of oxygen and the time a pilot is unable to perform flying duties effectively.
- At 30,000 feet, TUC is 90 seconds with a slow loss of pressure and 45 seconds with rapid depressurization.
Questions about Flight Physiology
- Which of the following stressors will make the aircrew member particularly susceptible to flicker vertigo?
- The answer is None of the above. Flicker vertigo is primarily caused by external factors like flashing lights, not by consumption of energy drinks, alcohol, or nicotine or psychosocial stress.
- An aircraft flying at 20,000 MSL has experienced a depressurization of the cabin. The co-pilot tells the PIC who does not immediately respond to verbal commands that the aircraft should descend. The PIC nods in affirmation but speaks incoherently and is unable to maintain controls due to loss of dexterity. The PIC is exhibiting which stage of hypoxia?
- The answer is Disturbance (70-79% oxygen saturation). This stage is characterized by impaired judgment, coordination, vision, and hearing, which is consistent with the PIC's symptoms described.
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Description
Explore the fundamental gas laws including Dalton’s, Boyle’s, Charles’s, Gay-Lussac’s, and Henry’s Law. This quiz will test your understanding of how these laws affect pressure, volume, and temperature in gases and their implications in real-world scenarios such as decompression sickness and trapped gas issues. Gain insights into the behavior of gases in various situations.
