From SKYbrary Wiki
The term Working Environment can be used to refer to a whole range of items and factors that may help or hinder a worker to perform effectively. These may include:
- Hardware – machinery, instruments, communication systems, tools, computers (and their interfaces), chairs etc.
- Infrastructure – runways, control towers, nearby towns, roads etc.
- Nature – topography, climate, weather, wildlife etc.
- Software – Policies, Rules and Procedures, checklists, job-cards, computer programmes etc.
- Colleagues (Liveware) – team/crew-members, supervisors, instructors, managers etc.
However, Working Environment is used most specifically to refer to the design and operation of aircraft cockpits and air traffic control towers (or controller operating positions). The cockpit is the most extreme environment with regards to constraint of design and exposure to operational hazards. Therefore, this article will focus on introducing the working environment of aircraft cockpits. Design concepts and operational factors that affect other (less extreme) environments, such as air traffic control, the ramp and the maintenance work-station, can be easily extrapolated.
Aeromedical Factors and Cockpit Design
Changes in design and operation of workplace environments have been closely linked with changes in medical assessments for licence holders (pilots and air traffic controllers). Aeromedical examiners assess pilots’ physical, cognitive and psychological abilities to cope with modern cockpit designs.
Aircraft cockpits are designed to facilitate pilots to function optimally not only under normal but also under critical conditions such as peak workloads and emergencies. Therefore, the design and operation of emergency checklists and personal protective equipment need to be even simpler and less prone to inducing errors. These are both key elements of a workplace environment which may become overlooked.
The size and shape of pilots directly affects the size and design of cockpits (anthropometry) which in turn influences the positioning of instruments and controls (ergonomics). Traditionally four elements need to be balanced in designing a pilot’s work-station:
- eye datum – the pilot, when sat in a neutral position, should be able to clearly see and read essential flight instruments
- lookout – with minimal head and body movement, the pilot should be able to scan a suitable portion of the sky in flight, necessary visual references when landing, and necessary references when manoeuvring on the ground
- controls – the pilot should be able to easily reach and manipulate all controls and functional mechanisms over their full range without undue effort or movement
- comfort – the pilot’s seat needs to provide adequate adjustments to attain the three elements above (eye datum, lookout and controls) as well as protect the pilot’s back against undue stress on the spine and back muscles.
Because, for the pilot, the major portion of information gathering is by vision, the limitations of human vision must be considered in the design, with respect to: acuity, the size and shape of the peripheral visual fields, and colour perception. This is especially critical against a background of many other visual influences from both inside and outside the cockpit.
Both Anthropometry and Ergonomics have been subsumed into the over-arching subject of Human Factors, which covers a much greater range of subjects and theories. Knowledge of Human Factors has directly affected the design of the pilot’s workplace environment, in particular the layouts, positioning, symbology and standardisation of critical flight and aircraft systems’ controls and displays. Perhaps a turning point in this knowledge came during the investigation of the Kegworth accident The Human Factors principle underpinning all workplace environment design is that the job and the workspace should fit the man and not the other way round.
Human physiology has evolved to function effectively within a small range of pressure differences that equate to altitudes close to sea level and which provide us with the highest concentrations of oxygen. At altitudes up to 10,000 ft a slight deterioration in physical and cognitive performance can be measured in most people. At altitudes above 10,000 ft deterioration of performance becomes more rapid and obvious due to Hypoxia. At altitudes above 25,000ft incapacitation is almost guaranteed and eventually death will occur. Therefore, aircraft operating above 10,000 ft are required to utilise pressurisation systems which maintain a comfortable ‘cabin altitude’, usually between 5,000 and 8,000 ft. The pilot’s workplace is therefore unnatural, although safe, but with a constant small risk of rapid decompression to a potentially dangerous altitude. In this likelihood, personal oxygen systems are available to reduce the impact and prevent Hypoxia.
Air at high altitude, as well as containing less oxygen, is extremely cold, can be very dry and also contain particles from the atmosphere. Aircraft use Environmental Control Systems (ECS) to regulate temperature, humidity and flow, and provide a very high quality of air to crew and passengers. The ECS will also filter-out particles, viruses and germs. The ECS will also convert harmful Ozone (which is increasingly present at higher altitudes) into oxygen.
Due to the high speeds that aircraft attain and the potential for sudden changes in direction and speed, humans become susceptible to Spatial Disorientation due to limitations of our Vestibular System.
Noise, Vibration and Fatigue
Noise in the workplace can greatly impact human performance, and whilst modern aircraft provide relatively quiet environments, at critical times of flight (e.g. below 10,000 ft) it is a requirement for pilots to wear protective headsets and communicate via the intercom. Vibration can also impact negatively on human performance, whether constant low-level or short-term severe, from air turbulence, an aircraft system malfunction, or damage to the aircraft structure. Both noise and vibration (and larger movements from turbulence) can induce fatigue in pilots earlier than might otherwise be expected.
Everyone on Earth is exposed to constant background galactic and solar Cosmic Radiation and occasionally additional exposure due to single events, such as solar flare activity. At higher altitudes the protective element of the Earth’s atmosphere is reduced and therefore pilots and aircraft systems are exposed to higher levels of cosmic radiation.
The working environment can also be affected by various psychological factors. As well as personal and workload stressors, more broad and pernicious factors can affect the workplace environment, such as Commercial Pressures and negative organisational cultures.
- Design for Humans, Steven Shorrock, Safeguard January/February 2018, Feb 2018.
- ^ ICAO SHELL Model.
- ^ a b c ICAO Doc 8984 Manual of Civil Aviation Medicine Edition 3.
- ^ Green, R, G. 1996. Human Factors for Pilots. 2nd Edition. Aldershot, UK. Ashgate Publishing Ltd.
- ^ UK AAIB Aircraft Accident Report No: 4/90 (EW/C1095). British Midland Airways, Boeing 737-400, G-OBME, 8 January 1989.
- ^ SKYbrary The Common Cold.
- ^ EASA Safety Information Bulletin 2012-09. 23 May 2012. Effects of Space Weather on Aviation.