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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.
Accidents & Incidents
Events in the SKYbrary database which include Ergonomics as a contributory factor:
- A109, vicinity London Heliport London UK, 2013 (On 16 January 2013, an Augusta 109E helicopter positioning by day on an implied (due to adverse weather conditions) SVFR clearance collided with a crane attached to a tall building under construction. It and associated debris fell to street level and the pilot and a pedestrian were killed and several others on the ground injured. It was concluded that the pilot had not seen the crane or seen it too late to avoid whilst flying by visual reference in conditions which had become increasingly challenging. The Investigation recommended improvements in the regulatory context in which the accident had occurred.)
- A124, Zaragoza Spain, 2010 (On 20 April 2010, the left wing of an Antonov Design Bureau An124-100 which was taxiing in to park after a night landing at Zaragoza under marshalling guidance was in collision with two successive lighting towers on the apron. Both towers and the left wingtip of the aircraft were damaged. The subsequent investigation attributed the collision to allocation of an unsuitable stand and lack of appropriate guidance markings.)
- A139 / A30B, Ottawa Canada, 2014 (On 5 June 2014, an AW139 about to depart from its Ottawa home base on a positioning flight exceeded its clearance limit and began to hover taxi towards the main runway as an A300 was about to touch down on it. The TWR controller immediately instructed the helicopter to stop which it did, just clear of the runway. The A300 reached taxi speed just prior to the intersection. The Investigation attributed the error to a combination of distraction and expectancy and noted that the AW139 pilot had not checked actual or imminent runway occupancy prior to passing his clearance limit.)
- A140, vicinity Tehran Mehrabad Iran, 2014 (On 10 August 2014, one of the engines of an Antonov 140-100 departing Tehran Mehrabad ran down after V1 and prior to rotation. The takeoff was continued but the crew were unable to keep control and the aircraft stalled and crashed into terrain near the airport. The Investigation found that a faulty engine control unit had temporarily malfunctioned and that having taken off with an inappropriate flap setting, the crew had attempted an initial climb with a heavy aircraft without the failed engine propeller initially being feathered, with the gear remaining down and with the airspeed below V2.)
- A306 / B744, vicinity London Heathrow UK, 1996 (On 5 April 1996 a significant loss of separation occurred when a B744, taking off from runway 27R at London Heathrow came into conflict to the west of Heathrow Airport with an A306 which had carried out a missed approach from the parallel runway 27L. Both aircraft were following ATC instructions. Both aircraft received and correctly followed TCAS RAs, the B744 to descend and the A306 to adjust vertical speed, which were received at the same time as corrective ATC clearances.)
- A306, East Midlands UK, 2011 (On 10 January 2011, an Air Atlanta Icelandic Airbus A300-600 on a scheduled cargo flight made a bounced touchdown at East Midlands and then attempted a go around involving retraction of the thrust reversers after selection out and before they had fully deployed. This prevented one engine from spooling up and, after a tail strike during rotation, the single engine go around was conducted with considerable difficulty at a climb rate only acceptable because of a lack of terrain challenges along the climb out track.)
- A306, Paris CDG France, 1997 (On 30 July 1997, an Airbus A300-600 being operated by Emirates Airline was departing on a scheduled passenger flight from Paris Charles de Gaulle in daylight when, as the aircraft was accelerating at 40 kts during the take off roll, it pitched up and its tail touched the ground violently. The crew abandoned the takeoff and returned to the parking area. The tail of the aircraft was damaged due to the impact with the runway when the plane pitched up.)
- A306, Stockholm Sweden, 2010 (On 16 January 2010, an Iran Air Airbus A300-600 veered off the left side of the runway after a left engine failure at low speed whilst taking off at Stockholm. The directional control difficulty was attributed partly to the lack of differential braking but also disclosed wider issues about directional control following sudden asymmetry at low speeds. The Investigation concluded that deficiencies in the type certification process had contributed to the loss of directional control. It was concluded that the engine malfunction was due to the initiation of an engine stall by damage caused by debris from a deficient repair.)
- A306, Yerevan Armenia, 2015 (On 17 May 2015, an Airbus A300-600 crew descended their aircraft below the correct vertical profile on a visual daytime approach at Yerevan and then landed on a closed section of the runway near the displaced runway threshold. The Investigation found that the crew had failed to review relevant AIS information prior to departing from Tehran and had not been expecting anything but a normal approach and landing. The performance of the Dispatcher in respect of briefing and the First Officer in respect of failure to adequately monitor the Captain's flawed conduct of the approach was highlighted.)
- A306, vicinity Birmingham AL USA, 2013 (On 14 August 2013, a UPS Airbus A300-600 crashed short of the runway at Birmingham Alabama on a night IMC non-precision approach after the crew failed to go around at 1000ft aal when unstabilised and then continued descent below MDA until terrain impact. The Investigation attributed the accident to the individually poor performance of both pilots, to performance deficiencies previously-exhibited in recurrent training by the Captain and to the First Officer's failure to call in fatigued and unfit to fly after mis-managing her off duty time. A Video was produced by NTSB to further highlight human factors aspects.)
- A306, vicinity JFK New York USA, 2001 (On November 12, 2001, an Airbus Industries A300-600 operated by American Airlines crashed into a residential area of Belle Harbour, New York, after take-off from John F. Kennedy International Airport, New York. Shortly after take off, the aircraft encountered mild wake turbulence from a departing Boeing 747-400.)
- A306, vicinity London Gatwick, 2011 (On 12 January 2011, an Airbus A300-600 being operated by Monarch Airlines on a passenger flight from London Gatwick to Chania, Greece experienced activations of the stall protection system after an unintended configuration change shortly after take off but following recovery, the flight continued as intended without further event. There were no abrupt manoeuvres and no injuries to the 347 occupants.)
"Ergonomics" is not in the list of possible values (Aircraft acceptance, ATC clearance error, ATC Unit Co-ordination, Authority Gradient, Data use error, Distraction, Fatigue, Flight / Cabin Crew Co-operation, Flight Crew / Ground Crew Co-operation, Flight Crew Incapacitation, Flight Crew Visual Inspection, Food Poisoning, Pre Flight Data Input Error, Inappropriate ATC Communication, Inappropriate crew response - skills deficiency, Inappropriate crew response (automatics), Inappropriate crew response (technical fault), Ineffective Monitoring, Maintenance Visual Inspection, Manual Handling, Pilot Medical Fitness, Plan Continuation Bias, Procedural non compliance, Spatial Disorientation, Stress, Violation, Dual Sidestick Input, Ineffective Monitoring - PIC as PF, Ineffective Monitoring - SIC as PF, AP/FD and/or ATHR status awareness, Malicious Interference, System/Component HMI, Pressure altimeter setting error, Pilot Startle Response, ATC Team Coordination) for this property.
- 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.