Flight Controls — Page 169, Lesson 224

I want to walk you through the flight controls chapter, and we're starting with the trim, flap, and speed brake selectors, then moving on to control position indicators. Let's take these one at a time. First, the trim selectors. On a professional aircraft, trim is how you relieve the control forces so the pilot doesn't have to hold constant pressure on the stick or rudder pedals. The trim selector is the cockpit control that lets you command that adjustment. It's typically a switch or wheel, and it sends an electrical or mechanical signal to the trim tab or the movable stabilizer, depending on the aircraft design. The key point here is that the trim selector is your input device — it's how you tell the aircraft to change the trim setting. Now, the flap selector. Flaps are the high-lift devices on the wing's trailing edge, and the flap selector is the cockpit lever or switch that positions them. You'll have discrete detents or settings — often labelled like UP, T/O, and LDG, or with degree markings. When you move the selector, it commands the flaps to extend or retract to that selected position. The selector isn't just a switch; it's tied into the flap control system, which includes the hydraulic actuators and the position sensing that tells the system where the flaps actually are. Then we have the speed brake selector. Speed brakes are the panels that deploy to increase drag and slow the aircraft, and the selector is the control that extends or retracts them. On many aircraft this is a lever on the centre pedestal, and it can be set to a range of positions, not just fully open or closed. The selector commands the speed brake panels to move to the chosen deflection. Now, here's the important part — the control position indicators. These are the cockpit displays that show you the actual position of these surfaces. The trim selector tells the system what you want, but the control position indicator tells you what the surface is actually doing. This is a critical distinction: command versus indication. You select a flap setting, and the indicator shows you the real flap position as it moves. You trim, and the indicator shows the trim tab or stabilizer position. These indicators are essential because they let you verify that the surface is responding correctly to your command. If you select flaps and the indicator doesn't move, or moves to the wrong position, you've got a problem — a jam, a hydraulic failure, or a control system fault. The indicator is your feedback loop, and in a professional cockpit you always cross-check the selector position against the indicator. Let me be clear on the relationship: the selector is the input, the indicator is the output display. They work together as a pair. You set the selector, and the indicator confirms the surface has moved to match. That's the core of how these controls function in the cockpit. I want to make sure you understand the terminology precisely. "Trim selector" — that's the specific name for the trim control. "Flap selector" — the flap control. "Speed brake selector" — the speed brake control. And "control position indicators" — the displays that show surface position. These are the exact terms you'll see on the aircraft and in the manuals, so use them precisely. Now, one thing to note: the chapter is structured so that these selectors come first, and then the indicators. That's deliberate — you learn the controls before you learn the displays, because the displays only make sense once you understand what they're showing. The indicators are the verification of the selectors' commands. Let me also mention that these are all part of the broader flight control system, but in this section we're focused specifically on the cockpit interface — the selectors and the indicators. The actual actuators, the hydraulics, the mechanical linkages — those come later in the chapter. Right now, we're looking at the pilot's interface with the system. So to summarise what we've covered: you have three selectors — trim, flap, and speed brake — each commanding a different control surface. And you have control position indicators that show you the actual position of those surfaces. The selectors are your commands; the indicators are your confirmation. That's the foundation for everything else in this chapter. Does that make sense so far