Chapter 33: Safety and Emergency Equipment
33.1 Aircraft Oxygen Systems
- Required to protect occupants from hypoxia (oxygen deficiency) at high altitudes, either
- during normal flight in unpressurized aircraft or following a depressurization in pressurized
- aircraft.
- Time of Useful Consciousness (TUC): The limited time a person has to take corrective
- action after an oxygen deprivation before losing consciousness. At 35,000 ft, this is only 30-
- 45 seconds.
- System Types:
- Gaseous Oxygen: Oxygen is stored in high-pressure green cylinders.
- Chemical Oxygen Generators: Commonly used for passenger oxygen. Pulling on the mask
- initiates a chemical reaction (Sodium Chlorate and Iron) that produces oxygen. Once started,
- it cannot be stopped and typically provides 15 minutes of oxygen.
- Mask Types:
- Diluter-Demand (Crew): Supplies oxygen only when the user inhales. It mixes cabin air
- with pure oxygen at lower altitudes and supplies 100% oxygen above ~32,000 ft.
- Continuous Flow (Passengers): Supplies a constant flow of oxygen once activated.
33.2 Fire and Smoke Detection/Protection
- Smoke Detectors: Located in cargo compartments and lavatories. They can be optical
- (photoelectric) types that detect light scattered by smoke particles, or ionization types that
- detect a change in air conductivity caused by smoke.
- Fire Detectors: Located in engine nacelles and APU compartments. Modern systems use a
- continuous fire wire or gas-filled tube that loops around the fire zones and triggers an alarm
- when it is heated to a set temperature.
- Fire Extinguishing:
- Fixed Systems: Fire bottles containing a halogenated hydrocarbon extinguishing agent (e.g.,
- Halon) are installed for the engines and APU. The pilot can discharge them from the cockpit
- after shutting down the affected engine.
- Hand-Held Extinguishers: Located in the cockpit and cabin for fighting internal fires.
33.3 Evacuation Systems
- Emergency Lighting: An independent, battery-powered lighting system that illuminates exit
- signs, the cabin, and escape paths for at least 10 minutes.
- Emergency Exits: Clearly marked doors and hatches. Over-wing exits and doors on large
- aircraft are equipped with inflatable escape slides which deploy automatically when the door
- is opened in the "armed" mode. Some slides can also be detached and used as life rafts.
- Personal Flotation Equipment: Life jackets are provided for flights over water. They are
- inflated by a CO₂ cartridge or orally.