Fire and Smoke — Page 167, Lesson 256

I want to walk you through the fire and smoke section of your operational procedures training. This is a critical safety topic, so let's take it step by step. We start with a table that tells us exactly how many hand-held fire extinguishers must be carried in the passenger cabin, based on the maximum approved passenger seating configuration. For 7 to 30 passengers, you need 1 extinguisher. For 31 to 60 passengers, you need 2. For 61 to 200, you need 3. For 201 to 300, you need 4. For 301 to 400, you need 5. For 401 to 500, you need 6. For 501 to 600, you need 7. And for 601 or more passengers, you need 8 extinguishers. Now, where two or more extinguishers are required, they must be evenly distributed throughout the passenger compartment. That means you don't just stack them all at the front galley — they have to be spread out so that no matter where a fire starts, a crew member can reach one quickly. There's also a specific requirement about the type of extinguisher. When the maximum approved passenger seating is greater than 31 but less than 60 — so that's 32 to 59 passengers — at least one of the two extinguishers must be Halon 1211. When the maximum approved passenger seating is greater than 61 — so 62 passengers or more — at least two of the extinguishers must be Halon 1211. Only Halon 1211 or water hand-held extinguishers are cleared for use on aircraft. Other extinguishants, like dry chemical or CO2, may be present in automatic systems, but they are not approved for hand-held use on the aircraft. Next, let's talk about fire classification. There is a classification system now in general use, and it is common practice to identify hand appliances by the class of fire they are intended for — for example, a 'Class A' extinguisher. Where an agent can be used against more than one class of fire, those agents are generally referred to as general purpose agents. I should note that this excerpt introduces the concept but doesn't list the specific classes — that detail would be covered elsewhere in your training. Now let's move to smoke. The effects of smoke are twofold: reduced visibility and physiological changes to people. The physiological changes include irritation to the eyes, irritation to the airways, over-stimulation of the nasal passages, and irritation to the lungs. In dense smoke, the rate of oxygen absorption in the lungs is reduced. After prolonged exposure, this leads to hypoxia — which is a deficiency of oxygen reaching the body's tissues — and that can progress to asphyxiation and death. Smoke in the cockpit is an obvious flight safety hazard. It diverts the attention of the pilot or pilots from flying the aeroplane to combatting the source of the smoke. That diversion of attention is the real danger — you're no longer fully focused on controlling the aircraft. Training drills are the best method of dealing with this particular hazard, but the success of any such drill relies on total crew co-operation. Both pilots must work together seamlessly. To combat the effects of smoke in the cockpit, smoke hoods are provided, or the supplementary oxygen mask is designed to provide protection from smoke ingress. The specific drills for donning and using this equipment will be detailed in the Operations Manual, or OM, and they will be type-dependent — meaning they vary from one aircraft model to another.