Single-engine Class B - Landing — Page 327, Lesson 402

Let’s start with the single most important idea for landing a single-engine Class B aeroplane: there is only one regulation requirement for this stage of flight. That requirement is that the landing distance must not exceed the landing distance available. In plain terms, the aeroplane must be able to land within the length of the runway. That’s the whole legal test for landing. Now, the regulation that governs this is found in CAP 698, and the relevant rule comes from EU-OPS. EU-OPS states that an operator must ensure that the landing mass of the aeroplane, for the estimated time of arrival, allows a full stop landing from 50 ft above the threshold within 70% of the landing distance available at the destination aerodrome and at any alternate aerodrome. Let me unpack that carefully, because every phrase matters. First, “landing mass” means the mass of the aeroplane at the moment of landing, and it’s assessed for the estimated time of arrival — that is, the predicted time you’ll actually touch down. Second, “full stop landing” means the aeroplane must come to a complete halt, not just touch down. Third, the landing is measured from 50 ft above the threshold — that’s the height at which you cross the runway threshold on a standard approach. And fourth, the key number: the aeroplane must be able to stop within 70% of the landing distance available. So even though the runway might be, say, 2200 ft long, the regulation only lets you use 70% of that length for your actual stopping distance. The factor to use for this calculation is 1.43. Let me show you how that factor works with an example. Suppose the landing distance available at the destination airfield is 2200 ft. The aeroplane must be able to land within 70% of 2200 ft. To find 70% of 2200 ft, you divide 2200 ft by 1.43. Doing that calculation gives you 1538 ft. So 1538 ft is 70% of 2200 ft, and therefore the aeroplane must be able to achieve a full stop landing within 1538 ft. That’s the practical meaning of the rule: you take the runway length, divide by 1.43, and that’s your allowable stopping distance. Now there’s another way to look at this same requirement, working in the opposite direction. Suppose you’ve calculated the landing distance of the aeroplane to be 1200 ft. The question then is: what is the minimum length of landing distance available that will allow a pilot to comply with the 70% rule? In this case, you simply multiply 1200 ft by 1.43. That gives you the minimum runway length required. So the factor 1.43 works both ways — divide the runway length by 1.43 to find the allowable stopping distance, or multiply your required landing distance by 1.43 to find the minimum runway length you need. Let me make sure the logic is crystal clear. The 70% rule means you’re only allowed to use 70% of the runway for stopping. So if you know the runway length, you divide by 1.43 to get the 70% figure. If you know your required landing distance, you multiply by 1.43 to get the runway length that gives you that 70% margin. The factor 1.43 is simply the reciprocal of 0.7 — it’s the mathematical bridge between the full runway length and the usable 70% portion. One more thing to note: this requirement applies not just at the destination aerodrome, but also at any alternate aerodrome. So when you’re planning a flight, you have to check this landing requirement for every airfield you might land at, not just your primary destination. And remember, the landing mass is assessed for the estimated time of arrival — so as the flight progresses and fuel is burned, the landing mass changes, and you must ensure that at the time you actually arrive, the aeroplane can still stop within that 70% limit.