Fire has three elements—fuel, oxygen and the heat. Take one away and it stops. With dangerous goods, you can get fire from the chemical reaction of flammable materials with an oxidising agent – you don’t necessarily need a source of ignition. A Class A fire is an ordinary one, that is, of normal combustible material on which water is most effective. A Class B fire is in a flammable liquid, such as oil or grease, where you would probably use a blanket. A Class C fire is electrical, for which you need a nonconducting extinguishing agent. For the latter two, you could use either Carbon Dioxide or Dry Powder (which ruins the avionics), but the fumes may be toxic, so you will need plenty of ventilation afterwards. A Class D covers other materials, such as metals, that may burn. To help you identify the source, smoke associated with electrical fires is usually grey or tan and very 270 Operational Flying irritating to the nose or eyes (it doesn't smell too good, either). Anything else (say from the heater) tends to be white, but you may get some black from upholstery. If you think you have an electrical fire, it's no good just using the extinguisher, because you may just be treating the symptom and not the cause, although there is a school of thought that advocates not using an extinguisher at all if you can possibly help it, due to the fumes and stuff you have to breath in till you land. Whatever you do, transmit a Mayday before it’s too late—you can always downgrade it afterwards. Bear in mind also that your first strike with your extinguisher is the best, because the contents and pressure decrease from then on. Next, put an oxygen or smoke mask on, if you have one, then bring on essential electrics one at a time until the smoke appears again. On the ground, engine fire drills may vary considerably between different types, and these will have to be memorised, but there are some general points that can be made. One is, before evacuating the aircraft, make sure the parking brake is off, so it can be moved somewhere safer if things get out of hand, always being aware that it could run off by itself, as well! If the fire has been caused by spilt fuel, has spread to the ground under the wing and the other engine has been started, taxi clear of the area (or more specifically, the fuel on the ground) before evacuation, keeping the fire on the downwind side. If the other engine has not been started, evacuate first, carrying out what drills you can. If you can, use the radio to summon help, and don't forget to take the extinguisher. Remember that human beings en masse need very different handling than when single. In the air, initial shut down actions are similar everywhere—after performing vital actions from memory (e.g. identifying the source and all that), refer to the checklist to see if you haven't forgotten anything. If the engine has been secured promptly, the fire should go out quickly after the fuel supply has been cut off. You will find, however, that structural failure of the wing will be imminent after about two minutes if the fire is uncontrolled, which is a sobering enough thought to make you commence emergency descent IMMEDIATELY, no matter how good it looks. If you've got extinguishers in the engine bays, delay actuating them until the engine has been secured and you've no reason to suspect a false alarm; that is, unless you can actually see signs of a fire. In the cabin, whether in the air or on the ground, the priority is to get out, and as soon as possible, because if the flames don't get you, the fumes will. The only difference between the two situations is how quickly this can be done, and what you can do about it. Legal Stuff The first point to bear in mind is that this chapter applies mainly to the UK, though there are enough hints for people elsewhere to benefit, especially in Canada, where the legal systems are similar, and a lot of it is international anyway. The second is quite simple—I am not a lawyer. I have had some training in it as part of wider Transport examinations, but I cannot lay claim to any great theoretical knowledge. However, in much the same way that you don't have to be a doctor to diagnose a headache, a layman can |