Aeroplane Equipment and Instruments — Page 90, Lesson 146

Let’s start with cabin lighting requirements. For aeroplanes that carry passengers, we need several specific types of illumination. First, there must be sources of general cabin illumination — that’s the main lighting that lets people see the cabin interior. Second, we need internal lighting specifically in the floor-level emergency exit areas, so that if the cabin lights fail or smoke reduces visibility, the path to those exits is still lit. Third, every emergency exit must have illuminated emergency exit markings and location signs — these are the signs that tell you where an exit is and how to operate it. Fourth, for all overwing exits and any exit where a descent assistance device is provided — like an escape slide or a rope — we need exterior emergency lighting on the outside of the aeroplane, so that after you open the exit, you can see the slide or the ground below. Now let’s move to the Emergency Locator Transmitter, or ELT. This is a radio transmitter that automatically activates in a crash to help search and rescue teams find the wreckage. The requirements depend on the passenger seat count and the date the aeroplane was first issued with its individual Certificate of Airworthiness — the CofA. For aeroplanes with more than 19 passenger seats, you have two options. Option one: you can carry one automatic ELT, or two ELTs of any type — meaning they could be automatic or manual. Option two: for aeroplanes first issued with an individual CofA after 1 July 2008, you must carry two ELTs, and at least one of them must be the automatic type. For aeroplanes with up to 19 passenger seats, the rules are slightly simpler. Option one: you can carry one ELT of any type. Option two: for aeroplanes first issued with an individual CofA after 1 July 2008, you must carry one automatic ELT. All ELTs that are carried to satisfy these requirements must transmit on two frequencies. The first is 121.5 megahertz — that’s the international distress frequency, used for homing, meaning search aircraft can home in on that signal to find you. The second is 406 megahertz — that’s the SARSAT data uplink frequency. SARSAT stands for Search And Rescue Satellite-Aided Tracking, and this frequency allows satellites to receive the ELT’s signal and relay your position to rescue coordination centres. Now let’s talk about survival equipment. This applies to aeroplanes operating over areas where search and rescue — SAR — would be particularly difficult. That could be over water, mountains, deserts, or remote jungle. In those cases, the aeroplane must be equipped with three things. First, signalling equipment to make the pyrotechnic distress signals described in ICAO Annex 2 — these are things like flares or smoke signals. Second, at least one ELT, which we just covered. Third, additional equipment for the route to be flown — this could include life rafts, survival kits, water, food, first aid, and so on. However, there are exceptions where that additional equipment is not required. The first exception: if the provision of SAR is not particularly difficult — meaning the area is well-covered by rescue services — and the aeroplane remains within a certain distance from an area suitable for making an emergency landing. That distance is defined differently depending on the aeroplane type. For an aeroplane capable of continuing the flight to an aerodrome with the critical power unit inoperative — that means it can still fly on one engine — the distance is 120 minutes at the one-engine-out cruising speed. For all other aeroplanes — those that cannot maintain flight on one engine — the distance is 30 minutes at cruising speed. And for aeroplanes certificated to EASA CS Part 25, or an equivalent standard — that’s the certification specification for large aeroplanes — the distance is no greater than 90 minutes at cruising speed from an area suitable for making an emergency landing. If the aeroplane stays within those time-based distances, you don’t need to carry the additional survival equipment for the route.