Human Performance in General Aviation

David O'Hare, David O'Hare

• Publisher: Routledge
• Year: 2017
• ISBN:
  9781351929714
• Edition: 1
• Topic: Tecnología e ingeniería
• Subtopic: Ingeniería aeronáutica y astronáutica

This is the first available edited collection of chapters on human performance in general aviation. Each chapter has been written by someone with knowledge of both the research literature and the operational background of general aviation. Chapters are designed to survey the current state of knowledge in areas critical to general aviation and to spell out both the operational implications of this knowledge and the directions needed for future research. Topics covered include strategies for flight instruction; the development of computer-based training; stress and decision making; skill development; the involvement of general aviation pilots in incidents and accidents; human factors implications of GPS use and the future of aircraft design and development in general aviation. The book provides an authoritative outline of currently applicable human factors knowledge for general aviation and a valuable guide to future developments. It features a foreword by Dr Stan Roscoe.

Part 1
Introduction

1 Introduction to Human Performance in General Aviation

David O'Hare

Introduction

The development of aviation clearly constitutes one of the great defining characteristics of the twentieth century. From the pre-World War I flying machine to the long-range, high-capacity, advanced-technology commercial jet of the 1990s lies a gap of a mere 95 years. Over 1,000 million fare-paying passengers were transported by commercial aircraft in 1996, returning an operating profit of US$12 billion to the airlines that carried them (ICAO, 1997). Unfortunately, 1,135 of those passengers lost their lives in 23 fatal scheduled air transport crashes Nevertheless, set against the numbers earned, such figures lend credence to the view that commercial air transport in the late 20th century is an exceedingly safe mode of transportation.

Of course it was not always this way. The accident rate in commercial transport has declined throughout its history. Advances in technology, especially the development of the reliable turbojet engine, and other developments in materials, navigation systems, and flying practices have all contributed. At the close-out of the twentieth century, increasing efforts are being devoted to tackling the most difficult problem of all—the contribution of human error to failures in the aviation system. This is generally alleged to contribute to 75-80% of air transport crashes.

However, if one thinks of aviation as a truly complex system involving the designers and manufacturers of all the equipment involved (aircraft, ATC, etc.), the maintainance of the components in the system, the organisation and management of all the processes involved, the selection and training of operational personnel (pilots flight attendants, controllers etc.) and the government regulators, then it could reasonably be pointed out that, unless one truly believes in 'Acts of God', almost 100% of crashes are due to some kind of human performance failure, somewhere in the system. For some reason, it is rarely pointed out that 100% of successful outcomes are also due to human performance.

The main focus for human performance analysis has been on commercial air transport. In view of the huge numbers of passengers carried, and the global economic significance of the air transport industry, this is perfectly understandable. As we turn the corner into the new millennium this will surely continue to be the case. It is possible to argue, however, that it is time that a proportion of this effort be re-directed towards other areas of aviation. There are at least two principal reasons for this. Firstly, the size and significance of the problems elsewhere in the aviation system are such as to warrant increased attention. Secondly, as the use of the term 'aviation system' implies, there is a fundamental inter-relatedness between different participants in the aviation enterprise. For example, small, general aviation (GA) aircraft and large commercial transports are often obliged to share the same airspace. The capabilities and performance of each affect the overall system outcome. At worst, a number of commercial air transport crashes have been attributed to airspace incursions by small, GA aircraft. The collision between an Aeromexico DC-9 airliner and a Piper PA-28 at 6500 feet over Cerritos in the LAX Terminal Control Area on August 31, 1986 (National Transportation Safety Board, 1998) provides a terrible example of the dangers.

In some respects, the overall safety of the system is determined by the performance of the weakest link. This may often turn out to be the single crew, low-technology, less rigorously trained GA operator rather than the multi-crew, high-technology, expensively trained air transport participant. The challenges facing the former are summed up in this comment from an ASRS report (Callback, June 1998) submitted by an airline captain: "This Bonanza is a lot harder to fly than the B-757 I drive at work". None of this should be taken to imply that all GA operators are incompetent, badly trained 'accidents-waiting-to-happen'. Far from it. Most GA operators are careful, responsible, and highly competent. However, the fact remains that the size of the accident problem in GA is considerably greater than that in the air transport sector, and the potential for unintended interactions between the two communities is ever present.

The General Aviation (GA) Problem

General Aviation is defined as "civil aviation other than scheduled and nonscheduled commercial air transport" (ICAO, 1997, p. 9). In practice, GA includes the private pilot flying simple, light, single engine aircraft such as the Cessna 172 or Piper PA-28, training organisations preparing pilots for private and commercial exams, agricultural and aerial work, air rescue services, business flights, and a host of other operations flown by both fixed-wing and rotary-wing aircraft. Of these, business and recreational flying accounts for the largest proportion of flying hours as shown in Figure 1.1

There are over half-a-million active GA private pilot licence holders alone, worldwide flying an estimated 337,910 aircraft used mostly in GA. As Figure 1.2 shows, both the total numbers of hours flown and the numbers of fatalities occurring in air crashes are greater in the GA sector than in the commercial air transport sector. In addition, the GA sector is responsible for a great many more departures and miles flown than the air carriers (Olcott, 1997). As David Hunter (Chapter 3) points out, very little is known about the characteristics of GA pilots.

Figure 1.1 Main sources of GA activity
Source: Year in Review, ICAO Journal, 1997

The more that is known about this group, the better we will be able to target effective improvements in regulation, education and training. Hunter reminds us of another very important point which is that virtually every pilot has at one time or another been a GA pilot, and that attitudes and behaviours developed at this stage are likely to influence performance further down the track.

This point is also emphasised by Irene Henley, Prue Anderson and Mark Wiggins (Chapter 4). They address a number of issues which arise in developing human factors training in GA with a particular focus on the role of the flight instructor. They also discuss in detail two innovative strategies, the use of reflective journals and problem-based learning, which can improve the learning process.

Whilst politicians and regulators focus almost exclusively on the toll arising from air transport crashes, the losses—both human and economic are as great, or greater in GA. Lives lost in concert, as in major disasters, are attention getting and newsworthy, whereas a similar toll spread thinly in ones and twos is easily ignored. This stark fact has resulted in public tolerance of high motor vehicle fatality rates and an apparent intolerance of 'disasters' involving multiple fatalities such as airliner crashes. It has also been claimed that the general public is willing to tolerate risk levels in voluntary activities (such as skiing or recreational aviation) that are approximately a thousand times greater than those from equally beneficial involuntary activities (Starr, 1969). If this is indeed true, and if it is taken as a prescriptive guide, then the almost exclusive focus on air transport safety might seem warranted. However, doubts have been raised about the validity of this assumption (Fischhoff, Lichtenstein, Slovic, Derby, and Keeney, 1981) and whilst a significant proportion of GA can be categorised as recreational (see Figure 1.1), a much greater proportion is undertaken for more utilitarian purposes.

Figure 1.2 Total flight activity levels and fatality levels for GA and Air Transport Operations
Source: Year in Review, ICAO Journal, 1997

It seems safer to assume that all loss of life is inherently undesirable and to the same degree. Aviation safety should be concerned with managing the risks of aviation to produce the fewest possible losses. This does not imply that the interests of the fare-paying passenger should be downgraded in any way, but that other participants in the aviation system are deserving of better efforts to understand and improve human performance and to make use of technological advances in all aviation systems which can lead to improved reliability and safety. In some areas of GA, such as sport and recreational aviation for example, so little attention has been paid to the scientific analysis of human performance that significant advances in understanding and consequent safety improvements might be relatively easy to achieve and would be extremely cost effective. In contrast, efforts to improve the already very low crash rate in the air transport sector will require significant advances in our understanding of human performance and improvements are likely to be extremely costly to implement throughout the industry.

Here Today ... Here Tomorrow

As noted above, the accident rates for commercial air transport have shown significant improvements since the beginnings of the commercial air transport industry in the 1930s. A particularly dramatic fall in accident rates has occurred since the introduction of jet airliners into commercial service in the 1960s. The reliability of jet engines compared to reciprocating engines was both directly (fewer engine failures) and indirectly (fewer powerplant problems meant fewer problematic situations for crew to manage) responsible for improved levels of safety. The rate of improvement in safety levels has of course decreased substantially in recent years (Nagel, 1988). GA aircraft are of course still predominantly of the piston-engine variety.

Safety levels in GA, defined in terms of accidents per 100,000 flight hours, can best be described as static. Figure 1.3 shows the GA accident rates for three countries—Australia, New Zealand and the U.S.A. between 1988 and 1994. Whilst the U.S rates are consistently a third lower than those in Australia and New Zealand, all three countries show completely static rates over this period. Unlike commercial air transport, there have been no major changes in GA aircraft technology during this time. Indeed, most of the aircraft which are flown in GA are essentially 1940s designs with cockpit displays and controls which have shown little change in decades. There are encouraging signs of significant changes on the way in GA design technology and these are discussed in some detail by Dennis Beringer (Chapter 10).

The impact of one new technological innovation, namely the development of cheap, portable GPS navigation units is now beginning to be felt throughout GA. The problems created by the proliferation of less than optimally designed GPS systems are discussed by Ruth Heron and Mike Nendick (Chapter 9). They consider both the basic ergonomics of the GPS system as well as problems arising from pilot training and flight preparation.

On the other hand, there has been an increasing recognition of the importance of human factors in pilot performance during this period, and some form of human factors training is now included in the pilot licencing syllabus in several countries. Unfortunately, it is not possible to draw any conclusions about the merits or otherwise of current forms of human factors training from these accident data. The normal caution about accidents being such rare events that underlying changes cannot be easily inferred is clearly applicable in this case. Also, since GA covers such a wide range of activities, aircraft, and pilots, the overall data may obscure individual trends in different areas. It is important therefore, to carefully examine the performance of different groups (e.g., rotary-wing versus fixed-wing, recreational versus aerial work etc.) so that similarities and differences can be properly determined.

Figure 1.3 GA accident rates for New Zealand, Australia, and the U.S.A. Sources: (NZ) O'Hare, Chalmers, & Bagnall, 1996, (AUS) The Parliament of the Commonwealth of Australia (1995) (USA) NTSB web page (http://www.ntsb.gov/aviation/aviation.htm/)

As the International Civil Aviation Organization (ICAO) has pointed out: "general aviation accidents constitute a major loss of resources. As a consequence, substantial benefits are to be gained from accident prevention programmes aimed at this group" (ICAO, 1984, p. 9). However, as David O'Hare (Chapter 4) points out, a safety programme is not solely about accident prevention. Losses in terms of personal injury and material damage can be reduced by interventions targeted at events occurring both during, and after, the crash sequence itself. The design of such interventions depends on the development of a sound understanding of the risk factors for injury and damage in aircraft crashes.

An important set of risk factors for GA accidents are related to weather conditions which are beyond the capabilities of the pilot, the aircraft, or both. In the United States alone "an average of 17 people a month are killed in aviation accidents attributable to weather" (AVflash Sunday, August 2, 1998). One potential solution lies in the provision of im...