Ergonomy — Page 9, Lesson 13

Let’s start with the word that titles this whole area: ergonomy. Ergonomy, also called human engineering, is the science of the relationship between people and machines. An ergonomic device is one that interacts smoothly with people’s bodies and actions. In aviation, that means designing the shape and position of controls, levers, and knobs so they are easy to operate and unlikely to lead to an incorrect selection. For instruments, it means designing them so they are unlikely to be misread, and locating them in a layout that makes the information easy and correct to interpret. That’s why standard layouts came to be adopted. Now, let’s look at location. The “flying” instruments — the ones that cover the handling of the aircraft — were arranged in a layout called the “basic six.” Other instruments tended to be scattered around the cockpit in positions most convenient to the designer and manufacturer, and seldom to suit the needs of the pilot. The basic six layout is shown in Figure 1.7: the airspeed indicator, the gyro horizon, the vertical speed indicator, the altimeter, the course indicator, and the turn and slip indicator. Since the introduction of the basic six, developments in aircraft instruments and operations led to the introduction of the “basic T,” which is shown in Figure 1.8, and the basic instrument panel of a Piper PA 34 Seneca is in Figure 1.9. Now, presentations can be in analogue or digital form. Analogue is typically a pointer on a dial, whereas digital is a row of numbers. Look at the two types of altimeter display in Figure 1.10 and Figure 1.11. With the three-pointer analogue system, the altitude information — say 24,020 feet — is harder to absorb at a single glance than with the digital display. The digital numbers are much easier to read. However, we note that one pointer still remains in the design of the mainly-digital presentation. Why? Because the human eye and brain cannot easily interpret rate information from moving numbers. While the altimeter is primarily designed to show altitude, with a separate instrument — the vertical speed indicator — to show rate of change of altitude, pilots pick up a lot of secondary information about vertical rate from the angular rate of the altimeter pointer. Finally, electronic displays. Historically, instruments have been located on instrument panels, though this is now changing with modern electronic displays. Compare the traditional layout in Figure 1.12 with the modern electronic, or glass, layout in Figures 1.13 and 1.14.