Just to remind ourselves what a Class B aeroplane actually is — Page 293, Lesson 368

We’re starting a brand-new chapter now, Chapter 7, and it’s all about take-off performance for single-engine Class B aircraft. Let me set the scene for you first, because this chapter sits on a very specific foundation. Just to remind ourselves what a Class B aeroplane actually is. A single-engine Class B aeroplane is a propeller-driven aeroplane with a maximum approved passenger seating configuration of 9 or less, and a maximum take-off mass of 5700 kg or less. So we’re talking about small, single-engine, propeller-driven machines — think of the typical training or utility aircraft, not the big jets. Now, the certification standards for these aeroplanes come from CS-23. CS-23 contains the requirements for normal, utility, and aerobatic category aeroplanes, and also for commuter category aeroplanes. So when we talk about Class B performance, we’re working within that CS-23 framework. Let’s move to the general operating requirements, which come from EU-OPS 1.525. These are the rules you must comply with when operating a single-engine Class B aeroplane for commercial air transport purposes. There are four of them, and each one is a hard restriction. The first is that this aeroplane shall not be operated at night. Straightforward — no night operations. The second is that the aeroplane must not be operated in instrument meteorological conditions, IMC, except under special visual flight rules, SVFR. So IMC is basically weather where you can’t see enough to fly visually, and SVFR is a special clearance that lets you fly visually in conditions that would otherwise be IMC. The rule says you can’t operate in IMC unless you’re under SVFR. The third requirement is that it must not be operated unless suitable surfaces are available en route which permit a safe forced landing to be made should engine failure occur at any point on the route. So you need to have somewhere along your route where you could put the aeroplane down safely if the engine quit. And the fourth is that this type of aeroplane must not be operated above a cloud layer that extends below the relevant minimum safe altitude. Now, the reason for that last one is easy to understand. If the engine were to fail in those conditions, it would be almost impossible for a pilot to see the landing surface, and therefore impossible to carry out a safe forced landing. You’d be above a cloud deck, you couldn’t see the ground, and you’d have no way to pick a landing spot. Now let’s get into the actual take-off distance definition, which comes from CS-23.51 and CS-23.53. The gross take-off distance for Class B aeroplanes — other than those in the commuter category — is the distance from the start of take-off to a screen height of 50 ft above the take-off surface. So we measure from where you begin the take-off roll all the way to the point where the aeroplane climbs to 50 feet above the runway. And this is done with take-off power set, rotating at VR — that’s the rotation speed, the speed at which you rotate the aeroplane to lift the nose — and achieving the specified speed at the screen. So the definition ties together the power setting, the rotation speed, and the speed you must reach at that 50-foot screen height. I want to pause there because that’s a dense definition, and it’s the heart of this chapter. The gross take-off distance is a certified performance figure — it’s the distance you need to get airborne and clear a 50-foot obstacle, under the specified conditions. We’ll build on this as we go through the chapter, looking at field length requirements, the factors you have to account for, surface conditions, and how the data is presented.