Decompression

• cabin is pressurised between 5000 - 7000 ft
• pressurisation begins at start of take off and cabin depressurises just before landing
• oxygen mask drop when pressure reaches 14000 - 15000 ft
• What are the 3 types of decompression?

  slow

  rapid

  explosive
• Slow decompression: gradual loss of cabin pressure which can take more than 10 seconds to equalise with the outside

  causes: small cracks in window seal or minor fault in pressurisation system

  signs: ears may pop and oxygen masks drop
• Time of useful consciousness:

  40,000 = 18 secs

  35,000 = 30 - 50 secs

  30,000 = 1 - 2 mins
• Rapid decompression: takes between 1 - 10 secs for pressure to equalise with outside
• Explosive decompression: takes less than 1 second for pressure to equalise with outside
• Signs of rapid/ explosive decompression:

  1. loud noise
  2. oxygen masks drop
  3. pain in ears and sinuses
  4. mist
  5. air thin and cold
  6. pain in stomach
  7. sudden boiling of liquids and bursting of packets and cans
• To fit flight crew oxygen:

  squeeze red levers to inflate

  release red levers to deflate

  set oxygen diluter lever on chin to 100%

  yellow blinker = breathing
• Once flight crew is conscious:

  stay in flight deck until PA

  "FSM to intercom immediately x2"

  cabin is then safe to move around
• once cabin is safe to move check:

  injuries

  damage to plane

  toilets

  other crew
• Which aircraft will descent automatically?

  A350
• What is the PA flight crew will make when descending?

  Cabin crew emergency descent x 2
• Decompression process:

  fit oxygen mask

  sit down

  fasten seatbelt

  breathe normally

  time 1 minute

  wedge cart and put brakes on
• Commands to shout in decompression:

  Grab mask

  Pull down

  Fit mask

  Breathe normally

  Fasten seatbelt

  Fit own mask before helping others