Let me set the scene for you — Page 293, Lesson 368

We're starting a brand-new chapter now — Chapter 7, "Single-engine Class B Aircraft – Take-off." This is where we leave the general mass and balance work behind and get into the specific performance rules for a particular class of aeroplane. Let me set the scene for you. First, we need to define exactly what a single-engine Class B aeroplane is, because that definition drives everything else in this chapter. 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 two hard limits: no more than 9 passengers approved, and the maximum take-off mass can't exceed 5700 kilograms. And it's propeller-driven — that's part of the class definition. Now, the certification standard that governs these aeroplanes is CS-23. CS-23 contains 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 the CS-23 certification framework. Next, we move to the general operating requirements, and these come from EU-OPS 1.525. You can find these in CAP 698, on page 1 of section 2, under paragraph 1.2. There are four general requirements about operating single-engine Class B aeroplanes for commercial air transport purposes, and I want you to hold onto each one because they're all operational restrictions. The first: this aeroplane shall not be operated at night. Straightforward — no night operations. The second: the aeroplane must not be operated in instrument meteorological conditions, IMC, except under special visual flight rules, SVFR. So IMC is generally off-limits, with that one narrow exception of SVFR. The third: 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. This is the big one for a single-engine machine — you need somewhere to put it down if the engine quits, anywhere along the route. And the fourth: 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 regulation is easy to understand. If the engine were to fail during these conditions, it would be almost impossible for a pilot to see the landing surface, and therefore impossible to carry out a safe forced landing. So that rule exists purely to keep a forced-landing option visible. Then we get into the take-off distance itself, and this is defined under 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 feet above the take-off surface, with take-off power set, rotating at VR, and achieving the specified speed at the screen. Let me unpack that definition for you, because every element matters. "Gross take-off distance" is the total distance measured from the start of take-off — that's the beginning of the take-off run — all the way to a screen height of 50 feet above the take-off surface. A screen height is an imaginary vertical obstacle, a reference height you must clear. For Class B, that screen is 50 feet. During this whole manoeuvre, take-off power is set, you rotate at VR — that's the rotation speed, the speed at which you begin to rotate the aeroplane to lift off — and you achieve the specified speed at the screen. So it's not just about reaching 50 feet; you must be at the required speed when you get there. And note the qualifier: this applies to Class B aeroplanes other than those in the commuter category. The commuter category has its own rules, which we'll get to later in the chapter. That's the foundation of this chapter — the class definition, the four EU-OPS operating restrictions, and the precise definition of gross take-off distance. From here we'll build into field length requirements and the factors that affect take-off performance.