We're starting a new chapter now — Chapter 15, Class A Additional Take-off… — Page 413, Lesson 505

We're starting a new chapter now — Chapter 15, Class A Additional Take-off Procedures. This is where we move beyond the standard, clean-runway take-off and look at the non-standard situations you'll have to handle as a professional pilot. Let me first set the scene. The chapter opens with a list of topics, and I want you to see the structure because it tells you exactly what "additional" means here. We have Non-standard Take-off Procedures, then Contaminated Runways, then Take-off with Increased V2 Speed, then Take-off with Reduced Thrust, then De-Rate, then Take-off with Anti-skid Inoperative, and finally the Questions and Answers. Now, before we dive into those, I want to address the two practice questions that appear at the very start of this excerpt, because they're actually a bridge from the previous chapter — they test your understanding of take-off mass limits. The first question asks about a value "ed for the certification file" — that's a typo in the source, it should read "used for the certification file." The options are four distances: 3050 m, 3513 m, 2555 m, and 2938 m. This is testing whether you can pick the correct take-off distance that gets certified for the aircraft's performance file. I'm not going to give you the answer here — these are the book's practice questions, and we'll try them one at a time when we get to them properly. The second question is more conceptual, and it's important because it sets up the whole logic of this chapter. It asks: when the outside air temperature increases, what happens to the field length limited take-off mass and the climb limited take-off mass? Let me unpack those two terms, because they're central to everything we do. The field length limited take-off mass is the maximum mass at which the aircraft can complete the take-off within the available runway distance — it's limited by how much runway you have. The climb limited take-off mass is the maximum mass at which the aircraft can still meet the required climb gradient after take-off — it's limited by how steeply the aircraft can climb with one engine inoperative, or with all engines, depending on the segment. Now, the physics here is straightforward. When the outside air temperature increases, the air becomes less dense. Less dense air means the engines produce less thrust, and the wings produce less lift for a given speed. So, for a given runway length, you need more distance to accelerate to the same take-off speed — which means the field length limited take-off mass must decrease. You simply can't lift as much weight off a fixed runway when the air is hot and thin. But here's the subtle part — the climb limited take-off mass. When the air is hot and less dense, the climb gradient also suffers, because the engines are producing less thrust. So the climb limited take-off mass also decreases. Both limits go down together when the temperature goes up. So the correct answer to that question is option c: the field length limited take-off mass and the climb limited take-off mass both decrease. That's the key relationship — hot air hurts both your runway performance and your climb performance. Now, let me show you the figures that accompany this chapter, because they illustrate the procedures we're about to study. That's Figure 15 — it shows the general layout of the take-off procedure we're discussing. That's Figure 15.2, which walks through the procedure step by step. And that's Figure 15.3, which shows sample data for a runway with 2 mm of contamination — we'll get to contaminated runways shortly. So, to summarize where we are: we're entering Chapter 15, which deals with non-standard take-off procedures. The two opening questions test your grasp of how temperature affects your take-off mass limits — and the answer is that both the field length limited and the climb limited take-off masses decrease when the outside air temperature rises. That's the foundation. Now let's move into the first topic: non-standard take-off procedures themselves.