Chapter 16 - Hazards of Aviation Flashcards
What are the symptoms of hypoxia?
Apparent personality change/euphoria
Head ache
Tingling in hand and feet
Pallor and cyanosis
Increased rate of breathing
Muscular impairment
Memory impairment
What factors determine a person’s susceptibility to hypoxia?
Altitude
Rate of decompression
Being cold (more energy and therefore oxygen needed for shivering)
Time (exposure)
Exercise
Extremes of temperature
Illness/fatigue
Alcohol/drugs
Smoking
Age
What happens to a persons oxygen carrying capacity if they smoke 20-30 cigaretts a day?
It reduces by 4-10%
What happens to a person’s physiological altitude if the smoke 20-30 cigaretts a day?
it raises by 4000-5000ft.
What level can a person who smokes 20-30 cigaretts a day get hypoxic?
6000ft
What are some prevention techniques to stop death/severe consequences from hypoxia?
Having a servicable oxygen supply in flights above 10000ft
Ensure passengers are correctly breifed
Fly only if 100% fit and not on medication or drugs
Ensure heaters are checked and enusure that fresh air is also brought into cabin.
What are some treatments for hypoxia while flying?
Go on oxygen
Decsend to sufficient oxygen level but no lower than minimum safe altitude.
What are the 4 zones of hypoxic hypoxia?
1) Indifferent zone (GL - 10000ft)
- Night vision affected as low as 5000ft
2) Compensatory zone (10000 - 15000ft)
- Automatic responses provide some protection against hypoxia to maintain homeostasis
3) Distrubance zone (15000 - 20000ft)
- Classic Symptoms of hypoxia
4) Critical zone (20000 - 30000ft)
- Homeostatic system can no longer cope
What are the 3 thresholds of hypoxia?
1) Reaction threshold (GL - 7000ft)
- dark adaption is adversely affected as low as 5000ft
2) Disturbance threshold (7000 - 12000ft)
- Auto responses provide some protection against hypoxia trying to maintain homeostasis.
3) Critical threshold - (12000 - 22000)
- Incapacitation with loss of conciousness follws with little or no warning.
What is the time of useful conciousness? (TUC)
The time available to a pilot to recognise the development of hypoxia and do something about it.
What will TUC be affected by?
Individual fitness
Workload
If the person is a smoker
Obesity
Decompression being progressive or explosive.
What are the rough TUCs at different altitudes?
20000ft - 30 minutes
30000ft - 1-2 minutes
35000ft - 30 - 90 seconds
40000ft - 15 - 20 seconds
How much will TUC be reduced by if somebody smokes?
50%
How does time of effective performance relate to TUC?
It will always be lower or the same.
What is hyperventillation?
Lung ventillation in excess of the bodys needs.
What can cause hyperventillation?
Anxiety
Motion sickness
Shock
Vibrations
Heat
High G-forces
Pressure breaathing (diving)
What are the symptoms of hyperventillation?
Dizziness & feeling unreality
Tingling
Visual disturbances
hot or cold sensations
Anxiety (creating a vicious cycle)
Loss of muscular coordination and impaired performance
Increased heart rate
Spasms
Loss of conciousness
What affect does hyperventillation have on the blood acidity?
it makes it more alkaline.
How do you treat hyperventillation?
Breathing in a paper bag (reintroduce CO2)
What should you do if you are unsure whether someone is hypoxic or hyperventillating?
Treat for hypoxia
What effect can decompression have on an aircraft?
The cabin altitude can rise by 5000ft
Sudden drop in temperature can cause mosting or fogging of windows
What are the procedures if a cabin decompresses?
1) Put on oxygen maskand set to 100%
2) Declare emergency
3) seatbelt sign on
4) Initiate a controlled descent to the higher of 10000 cabin altitude or minimum safe altitude.
5) Once landed obtain medical advice for recompression
Who should you first look after following decompression?
Yourself
How does decompression sickness come about?
From nitrogen in the blood coming out of solution in the form of bubbles.
Associated with heights of around 18000 - 25000ft
Unlikey below 14000ft
