Inceptors and displays

This tour of flying qualities would not be complete without some discussion on the other key characteristics associated with the air vehicle that have a primary effect on flight path control – the pilot’s inceptors and displays. To dispel any myths that these are secondary issues it must be said that poor characteristics in either of these two areas can ruin otherwise excellent flying qualities. Of course, pilots can and will compensate for poor mechanical characteristics in cockpit controls, but the tactile and visual cues provided through these elements are essential for many flight phases. Sidestick controls and helmet-mounted displays are components of ACT and are likely to feature large in the cockpits of future helicopters (Figs 2.48, 2.49). Examples of recent research with these devices will be outlined in Chapter 7.

Operational benefits of flying qualities

So, what are the operational benefits of good flying qualities? Are they really significant or merely ‘nice to have’? We have seen that one of the potential consequences of flying qualities deficiencies is loss of control, leading to structural damage, pilot disorientation and a crash. We have also seen that an aircraft that exhibits Level 1 characteristics in one situation can be Level 2 or even 3 in degraded or more demanding conditions. A question then arises as to the likelihood of a aircraft running into these situations in practice. This topic has recently received attention in the fixed-wing civil transport community in an attempt to quantify the probability of human error leading to a crash (Ref. 2.38). The same approach was taken to quantify the benefits of having baseline Level 1, as opposed to Level 2, flying qualities for military rotorcraft (Ref. 2.39). This research, which will be described in more detail in Chapter 7, derived a result that is summarized in Fig. 2.50. This shows the probability of achieving MTE success,

failure or loss of control (leading to a crash) as a function of mean HQR (derived, for example, from an ADS-33 objective assessment). The results are somewhat intuitive and fall out from fairly simple statistical analysis. There are a number of assumptions that need careful examination before the kind of results depicted in Fig. 2.50 can be substantiated, however, and these will be pursued further in Chapter 7. The approach, while somewhat controversial, has considerable appeal and opens up opportunities for providing a direct effectiveness measure for flying qualities.