Aerodromes - Physical Characteristics — Page 381, Lesson 519

Let’s pick up with the physical characteristics of aerodromes, specifically the runway strip. I want to walk you through what it is, how it’s sized, and how it’s protected. First, the definition. A runway strip is an area that includes the runway, and the stopway if one is provided. Inside this strip, obstacles are kept to a minimum. Any obstacle that does exist must be constructed so it presents the minimum danger to aircraft — in other words, it must be frangible, meaning it collapses upon impact. The purpose of the runway strip is twofold: it reduces the risk of damage to an aircraft that runs off the runway, and it protects aircraft flying over it during take-off or landing operations. Now, the length. The runway strip should extend before the threshold and beyond the end of the runway or stopway. The minimum distance is 60 metres where the code number is 2, 3, or 4. It’s also 60 metres for a code 1 instrument runway. But for a code 1 non-instrument runway, that distance drops to 30 metres. So remember the contrast: code 1 non-instrument gets 30, everything else gets 60. Next, the width. The strip should extend laterally on each side of the centre line of the runway, and its extended centre line, throughout the length of the strip. The distance depends on the runway type and the code number. For a precision runway, code 1 or 2 gets 75 metres each side, and code 3 or 4 gets 150 metres. Non-precision is the same: 75 for codes 1 and 2, 150 for codes 3 and 4. Non-instrument is different: code 1 gets 30 metres, code 2 gets 40, and codes 3 and 4 get 75. Now, grading. For an instrument runway, the portion of the strip within a certain distance from the centre line must be graded for aeroplanes in case one runs off. That distance is at least 75 metres for code 3 or 4, and 40 metres for code 1 or 2. And here’s a critical detail: the surface of that portion of the strip that abuts a runway, shoulder, or stopway must be flush with the surface of the runway, shoulder, or stopway. No step, no lip — flush. Then, objects on the strip. No fixed objects other than visual aids — specifically PAPIs, the precision approach path indicators — are permitted within 77.5 metres of the centre line for a code 4F precision CAT I/II/III runway. For code 3 or 4 precision CAT I/II/III, that distance is 60 metres. For code 1 or 2 CAT I, it’s 45 metres. No mobile objects are permitted on this part of the strip during landing or take-off. And any object within those stated dimensions is regarded as an obstacle and, as far as practicable, removed. Finally, the Runway End Safety Area, or RESA. This is an area of land, usually at each end of the runway strip, on either side of the extended centre line. It does not form part of the runway for operational — performance or planning — purposes. It’s free from obstructions and set aside in case an aeroplane overshoots or overruns the end of the runway. Its primary purpose is to reduce the risk of damage to the aeroplane. RESAs should be provided for all code 3 and 4 runways, and for code 1 and 2 instrument runways. The RESA should be at least twice the width of the runway, and extend from the end of the runway strip for a distance not less than — and that’s where the excerpt cuts off, but the figure shows the width of runway strips. That’s the runway strip in full — definition, length, width, grading, object restrictions, and the RESA.