Human Factors for Civil Flight Deck Design

Don Harris, Don Harris

• Publisher: Routledge
• Year: 2017
• ISBN:
  9781351929837
• Edition: 1
• Topic: Negocios y empresa
• Subtopic: Industria del transporte

Human error is now the main cause of aircraft accidents. However, in many cases the pilot simply falls into a trap that has been left for him/her by the poor design of the flight deck. This book addresses the human factors issues pertinent to the design of modern flight decks. Comprising of invited chapters from internationally recognised experts in human factors and flight deck design, contributions span the world of industry, government research establishments and academia. The book brings together the practical experience of professionals across the human factors and flight deck design disciplines to provide a single, all-encompassing volume. Divided into two main parts, part one of the book examines: the benefits of human engineering; flight deck design process; head down display design; head-up display design; auditory warning systems; flight control systems, control inceptors and aircraft handling qualities; flight deck automation; and human-computer interaction on the flight deck and anthropometrics for flight deck design. Part two is concerned with flight deck evaluation - the human factors evaluation of flight decks; human factors in flight test and the regulatory viewpoint Of interest to all human factors professionals operating in high technology, high-risk dynamic industries as well as those engaged directly in aerospace activities, the book will also be of key importance to engineers with an interest in human factors for flight deck design, academics and third year and post-graduate human factors/ergonomics and psychology students.

Section One
Flight Deck Design

1 Flight deck design and integration for commercial air transports

Brian D. Kelly

Introduction

About 35 years ago, the world had discovered how to fly efficiently anywhere in the world at high subsonic speeds without benefit of advanced flight deck technology and crew interfaces. Since that time, safety has improved so dramatically that the industry now has the luxury of concentrating its efforts for improving safety on a relatively few agendas. Robust technological solutions are in sight for major causes for accidents involving the flight crew, especially controlled flight into terrain, loss of control, and approach and landing. So one might legitimately question whether much more advancement in the state of this art is justified.

Nowhere other than a commercial aircraft flight deck can one find a system involving extensive interactions with human beings which is as complex and critical to public safety and yet so commonplace. Furthermore, the interactions and complexities do not end on the flight deck, but extend into many other infrastructures such as air traffic control. Flight deck (cockpit) design, and operational practices in commercial aviation have experienced significant evolution since the introduction of the jet age in the early 1960s. During the last four decades the industry has accomplished a revolution in digital avionics enabling new kinds of flight deck displays and controls, communication, navigation, surveillance, and aircraft system management. The role of the flight crew has shifted, and new methods and standards for training of flight crews have also emerged. During this time, safety has improved dramatically, and commercial aviation remains the safest mode of transportation, not withstanding the fact that deregulation has simultaneously increased pressure to improve efficiency and reduce costs while the business has grown exponentially. The challenge now is to increase efficiency and reduce costs while continuing to maintain safety margins.

Flight decks have evolved from a place where the pilots sit amidst numerous independent and disparate indications and controls toward integrated designs where the pilots and all of the aircraft systems come together and operate as an integrated whole.

This chapter examines the problem from a manufacturer's perspective. It begins with an outline of an aircraft programme, showing the kinds of tasks and deliverables expected of Human Factors and flight deck integration organisations, followed by a discussion of design considerations to provide a practical sense of the depth and breadth of design challenges. Further discussions cover integration and proper application of Human Factors disciplines including the philosophies, tools, methods, and areas of expertise required to meet the needs. Emphasis is placed on the necessity of achieving balance and appropriate compromises between dissimilar requirements (the essence of practical integration), and of the need to bring multiple dissimilar areas of talent to bear on this complex and crucial part of the aircraft design. The chapter concludes with a discussion of future challenges and opportunities in the hope that the reader will conclude that much interesting work lies in the decades ahead.

The major sections are:

• Crew interface development in the context of an engineering programme.
• Some specific flight deck design considerations.
• Human-centred design philosophies and design strategies.
• Assuring integration.
• Test and evaluation strategies for programme phases.
• Organisational considerations.
• Challenge and opportunity.

Crew interface development in the context of an engineering programme

The life cycle of an engineering programme has many phases and milestones, and usually follows or has elements of the following:

• Research and development, concept development.
• Product development, design integration, market assessment, high-level design requirements.
• Initial configuration and performance definition.
• Authorisation to offer a product.
• Programme kick-off, and announcements of orders.
• Initial detailed design requirements.
• Validation of design requirements, emphasis on integration.
• Certification plans, and their concurrence from authorities.
• Preliminary Design Review (PDR).
• Final design requirements, Design freeze.
• Design specification and drawing releases.
• Critical Design Review (CDR).
• Component build,
• Verification testing of flight hardware and software.
• Final integration.
• Flight Test.
• Certification and delivery.
• Fleet experience, support, lessons learned.

This pattern is shown in figure 1, with typical flight deck and crew interface design activities shown in the lower half, (Jacobsen, Kelly, Mumaw and Hilby, 2002).

Figure 1 Engineering programme phases and related human interface development activities

Configuration control is typically imposed early in the programme to allow time for detailed design, build, delivery, integration, and test. Therefore, the critical pilot interface design decisions should be finalised as part of the initial design process, to support detail design specification and drawing releases. This underscores the necessity of the involvement of Human Factors and operational specialists early in the design.

The flight deck controls and displays are part of the design of virtually every other aircraft system. So, it is critical that the design decisions for the flight deck and crew interfaces be made in concert with those for other parts of the aeroplane. Because the value of effective flight deck design is often difficult to quantify, these aspects are particularly vulnerable to deletion or simplification if their design and validation is not completed before design of aeroplane systems is frozen.

New designs

Design of an all-new vehicle (as opposed to a derivative of an existing design) requires greater resources and expertise early in the programme, especially if significant advances in technology, configuration, or processes are being applied. Testing of concepts and validation of the design requirements characterise the front end of the programme, with particular emphasis on any novel interfaces or design features.

Derivative designs

So called 'derivative programmes', where the design is based on improvements to an existing product, are driven by economic necessity to require fewer resources and usually require a high degree of commonality in training and operations with the existing product. This shifts the emphasis in crew interface design to one of sufficient involvement in changes to the systems to ensure that commonality with existing operations stays within limits. In a more complete treatment of this aspect, Boyd and Harper (1997) show how Human Factors and operational considerations are critical to the design of a derivative flight deck, where judicious and creative compromises should be struck between innovation and the need for commonality with past versions of the design.

Retrofit

With an installed fleet of over 10,000 commercial transports in service with useful product lives measured in decades, it is no surprise that business opportunities for servicing and upgrading the world fleet are substantial. Retrofits have enabled significant safety improvements such as predictive windshear systems, Terrain Awareness and Warning Systems (TAWS), and head-up displays. Retrofits of such systems have high safety leverage because a larger fraction of the world fleet can benefit in a comparatively shorter time.

Retrofits in the near future are likely to involve new communications systems and means of sharing data between the aeroplane and ground as air traffic infrastructures and operations change to accommodate increasing traffic. Retrofit of modem flight deck technology to older aeroplanes can be driven by maintenance costs associated with obsolete technology, consolidation of functions into fewer units, or in some cases by enabling a two-crew flight deck.

Some specific design considerations

Requirements for the design of commercial flight decks cover the full range of ergonomic, environmental, perceptual and cognitive considerations. To progress beyond current practice, a clear understanding of the sciences involved is needed to ensure that errors in new design concepts are caught. But the problem is sufficiently complex that awareness of the history and rationale behind current practice and requirements should also be kept in mind. Therefore, the traditional, but important, issues of ergonomics, geometry, and environment are discussed before proceeding to the more popular design considerations associated with cognitive tasks.

Basic ergonomics, geometry and arrangement

Spatial arrangement and the physical ergonomics of a flight deck begin at the eye reference point, or ERP. From this 'design eye' position, internal and external vision, reach, strength, and accessibility are addressed. The general arrangement of a 777 flight deck is shown in figures 2 and 3.

Figure 2 Boeing 777 flight deck arrangement

Figure 3 Boeing 777 flight deck

The exterior shape of the aeroplane is of course strongly influenced by aerodynamic concerns. But the best aerodynamic shape for the nose of an aeroplane is one with minimum volume and disruption of flow, and therefore at cross purposes with flight deck equipment volume and external vision requirements. FAR/JAR 25.773 regulates external vision for the pilots. Advisory circular AC 25.773 documents acceptable means of compliance. The primary considerations are the vision 'polar', a plot of the window edges from the ERP in spherical coordinates, and the 'three-second rule, depicted in figure 4.

The polar establishes a minimum standard for view of the outside world for safe accomplishment of any procedure or manoeuvre and collision avoidance. The three-second rule ensures sufficient vision over the nose in poor weather to assess the runway environment at low altitude on final approach. The viewable segment of ground must not be covered in less than three seconds. Therefore this criterion influences the required approach speed and attitude of the aeroplane. The vision cut-off line in turn affects the amount of available front panel and glare shield panel areas. Other sections of the AC address optical properties of the transparencies, post width, and other blockages.

Reach and accessibility of controls are also addressed from the ERP, and include devices such as flight controls, aircraft systems controls, landing gear, thrust levers, reversers, rudder pedals, tiller, window opening, oxygen masks, flight bags, charts, etc. Also, FAR 25.1523 and Appendix D establish criteria for determining the minimum flight crew and require that either flight crew member be able to reach and operate all controls necessary if the other pilot is incapacitated.

Figure 4 External vision guidelines from FAA AC 25.773-1

Seats must be designed to withstand 16g crash loads, subject to a head impact criterion (HIC). Strength and flexibility of the seat, restraints, and cushions are obvious considerations, but a windshield that is too close to the path that the head follows or glare shield and panel structures which do not absorb enough energy can also lead to failure of this test.

Seat cushions firm enough to comply with HIC, may present challenges in designing for comfort. Comfort testing, particularly for long-range aircraft should employ a variety of statures, and evaluations after being seated for at least two hours. Seat and rudder pedal adjustments are usually employed to provide appropriate accessibility to controls for pilots ranging in stature from 5'2' (153 cm) to 6'3' (183.5 cm) (FAR/JAR 25.777). Beyond that, the seats should also be sufficiently adjustable to accommodate ingress and egress without interference with the flight controls, and napping if operational approval of that practice is anticipated.

The length of the flight deck behind the ERP is driven by considerations such as space for observer seats (required under operating rales, e.g. FAR Part 121) stowage and accommodations, and space for emergency equipment. The flight deck must also provide an alternate means of escape for the flight crew, which is usually accomplished by openable windows or a hatch.

Internal vision requirements include readability of instruments and displays in all lighting conditions, and avoidance of obscuration from flight or thrust controls. Readability of displays and lighting of instruments are strongly influenced by the wide range of ambient lighting conditions. Reflections pose a particular challenge due to the complex geometry and arrangement of reflective su...