04 Atmosphere, Oxygen And Respiration

Question 1

Cabin pressure is usually maintained at?

Answer 1

6,000 to 8,000ft

Question 2

What is the % of Oxygen in the lungs at sea level?

Answer 2

13.7%

Question 3

What are the 3 thresholds of Hypoxia and their symptoms?

Answer 3

• Reactionary threshold (7,000ft)
  
  • Night vision adaption is lost - as low as 5,000ft
• Disturbance threshold (7,000 to 12,000ft)
  
  • Automatic responses provide some protection and try to maintain homeostasis
• Critical threshold (12,000 to 22,000ft)
  
  • Incapacitation and loss of conciseness follows with little warning

Question 4

What are the oxygen requirements at different altitudes for an unpressurised AC?

Answer 4

0 - 10,000ft: just air

10,000 to 33,700ft: O2 and air mix, keeps body on the ground

33,700ft: 100% O2, keeps body on the ground

33,700 to 40,000ft: 100% O2, keeps the body at 10,000ft

40,000+: 100% O2 under pressure, keeps the body’s at 10,000ft

Question 5

Haemoglobin saturation levels at different altitudes

Answer 5

MSL: 95.7%

10,000ft: 87%

20,000ft: 65%