CABIN ALTITUDE WARNING or Rapid Depressurization

RAPID DECOMPRESSION

• outflow valve malfunction
• door operning
• structural damage
  (e.g. bomb explosion)

SLOW DECOMPRESSION

• outflow valve malfunction
• presurization controller fault
• incorrect pressurization setup
• door seal damaged or missing
• fuselage damaged by ground vehicle
• toilet flush valve jammed open

A rapid decompression is one in which cabin pressure increases by 7,000 fpm or more, generally accompanied by cloud formation inside the airplane. Any idea how this feels like ? Just look at the speed and sound next time yu flush the aircraft toilet!

Recently delivered and retrofitted aircraft have red warning lights installed on the captain’s and F/O’s forward instrument panel that illuminate when the cabin pressure altitude exceeds 10,000 feet.

! Make sure to distinguish a full scale cabin rate of climb ( = cabin out of control) from a full scale cabin rate of descent ( = cabin pressure recovering) !

If the Aft Main Outflow Valve is fully closed and cabin pressure continues to climb or equals your actual flight altitude, structural damage or an open door can be suspected.
In this case, pressurization cannnot be recovered, start your descent immediately.

If the PASS OXY ON amber light does not illuminate with the cabin altitude exceeding 14,000 feet or after manually placing the Passenger Oxygen switch to ON, the P18-3F may have tripped.

! The time of useful consciousness without oxygen at 40,000 feet is 15 seconds only and at 35,000 feet this is only 20 seconds.
Because eyes and brain have a high metabolism and cannot store oxygen, they are most sensitive to oxygen depletion. In casef slow decompression, one of the early symptoms of hypoxia is a decline is sight and a blue tine on the lips and under the fingernails. Other phusical effects of decompression include faster breathing, higher pulse rate, euphoria, a tingling sensation in the fingers, blurred vision, sinus pain, muscle pain, etc...