Air Traffic Control: Human Performance Factors

Anne R. Isaac, Bert Ruitenberg

• Publisher: Routledge
• Year: 2017
• ISBN:
  9781351959957
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Aviation
• Index: Technology & Engineering

From the Foreword by Captain Daniel Maurino, ICAO: '...Air Traffic Control...will remain a technology-intensive system. People (controllers) must harmoniously interact with technology to contribute to achieve the aviation system's goals of safe and efficient transportation of passengers and cargo...This book...considers human error and human factors from a contemporary and operational perspective and discusses the parts as well as the whole...I hope you enjoy reading it as much as I did.' The motivation for writing this book comes from the author's long standing belief that the needs of Air Traffic Service personnel are inadequately represented in the aviation literature. There are few references to air traffic control in many of the books written for pilots and about pilots and this is also observed at the main international conferences. In line with the ICAO syllabus for human factors training for air traffic controllers, the book covers the main issues in air traffic control, with regard to human performance: physiology including stress, fatigue and shift work problems; psychology with emphasis on human error and its management, social psychology including issues of communication and working in teams, the environment including ergonomic principles and working with new technologies and hardware and software issues including the development of documentation and procedures and a study of the changes brought about by advanced technologies. Throughout the text there are actual examples taken from the air traffic control environment to illustrate the issues discussed. A full bibliography is included for those who want to read beyond these issues. It has been written for all in air traffic services, from ab initio to the boardroom; it is important that the men and women in senior management positions have some knowledge and awareness of the fundamental problems that limit and enhance human performance.

1 The Need for Human Factors

IT WAS SO OBVIOUS - so painfully obvious - but most of those engaged in commercial aviation couldn't see it, or wouldn't. Human beings engaged in a human enterprise are subject to human failures. Pilots and controllers and maintenance people err and cause accidents because they are human, and we imperfect humans are all prone to make such mistakes. Discovering that a human error - pilot or otherwise - has occurred is merely the starting point. To have any hope of preventing such an error from causing such an accident again and again, the reason the error was made in the first place must be discovered, and the underlying cause of that human failure must be revealed and addressed in future operations.

J.J. Nance, 1986.

1.1 The Past

Human factors has become a major concern in aviation, especially since the International Civil Aviation Organization (ICAO) adopted a resolution on Flight Safety and Human Factors at its 1989 Assembly. From this meeting the Air Navigation Commission formulated the following objective for the task

To improve the safety in aviation by making States more aware and responsive to the importance of human factors in civil aviation operations through the provision of practical human factors material and measures developed on the basis of experience in States. ICAO, 1989.

ICAO has described human factors as a concept of people in their living and working situations; about their relationship with machines, with procedures and with the environment; and also about their relationships with other people. In aviation, Human Factors involves the consideration of personal, medical and biological variables for optimal flying and Air Traffic Control operations (ICAO, 1989). Many people have discussed the concepts within the Human Factors area and most agree on the main objectives. These are to enhance the effectiveness and efficiency with which work and other activities are carried out by people, and also to maintain and enhance certain desirable human values such as safety, health and wellbeing. The main approach of human factors is the systematic application of relevant information about human abilities, characteristics, behaviours and motivation and communication patterns in the execution of work and social interactions.

Human factor activity has exploded in the last 250 years. This development can be viewed during several phases. The time between 1750 and 1890 was characterized by new inventions such as the harnessing of steam power to machinery which could be applied to specific applications, most notably the textile industry.

During 1870-1945 a major expansion in the use of power in manufacturing, transportation, and agriculture was seen. The first part of this phase also saw the development of the science of behaviourism. Early developments in this field included elementary 'time and motion' studies in which actual and ideal work practices were analysed in order to determine more optimum ways of achieving greater efficiencies in work outputs.

During 1921 in the United Kingdom, the National Institute for Industrial Psychology was established to undertake experimental studies regarding the benefits to be gained in industry and commerce. Some of the findings of this Institute, later confirmed in World War II, found that some machines could not be operated safely or effectively by many people. In the United States from 1924-1930 a major research programme was undertaken at the Hawthorne Works of Western Electric. This study concluded that work effectiveness could be favourably influenced by psychological factors not directly related to the work itself. This psychological effect has come to be known as the 'Hawthorne' effect.

During the Second World War an even greater stimulus for human factor developments was established. New technology, especially radar and advanced aircraft systems, appeared to be exceeding the abilities of ordinary people. At Oxford University a Climatic and Working Efficiency Research Unit was established to investigate the requirements for optimising the interface between humans, the physical environment and machines. At Cambridge University, Professor Sir Frederick Bartlett was requested in 1939 by the Medical Research Council to undertake research regarding the problems with military aviation. A simulator built around a Spitfire cockpit was constructed to test how pilot performance could be improved by changing the design, layout and interpretation of displays and controls. This early simulator, known as the 'Cambridge Cockpit', generated significant information relating to aircrew selection, pilot training, the effects of sleep loss and fatigue and various aspects of visual perception and display design. One of the earliest studies (Drew, 1940) demonstrated that when pilots suffered significant loss of sleep and were fatigued, their ability to maintain a complex array of tasks was reduced. Undue attention tended to be paid to one or two instruments while other activities such as checking fuel contents were overlooked. These studies provided firm evidence that machines, systems and procedures needed to be made to match the characteristics of humans, rather than humans being made to fit the characteristics of machines with their inherent systems and procedures.

From 1946 to 1960, the development of human factors (or ergonomics) as a technology in its own right was established. At this stage it should be noted that the term ergonomics which was first used by Professor Murrell in 1949, derives from the Greek words ergon (work) and nomos (natural law). Thus the derivations led to the definition 'a study of human behaviour in work'. In the United States and Europe ergonomic societies were formed to provide more systematic ways of developing and disseminating the mounting scientific studies. In the United Kingdom, the Ergonomics Research Society, formed in 1949, became the International Ergonomics Association in 1959. In the United States, where the preferred name was human factors rather than ergonomics, the Human Factors Society was founded in 1957 and affiliated with the European branch.

It was first calculated in 1940 that three out of four aircraft accidents were due to human failures of one kind or another. This figure was confirmed by the International Air Transport Association (IATA) at their Istanbul conference in 1975, where it is well recognised that the initial development of Human Factors within aviation began.

An example of such human failing occurred in 1977 when two aircraft collided on the runway at Tenerife airport killing 583 people and creating the greatest disaster in aviation history. One of the two aircraft which collided was from the Dutch carrier KLM. It is perhaps not surprising that within a year of this accident, that airline had launched the first 'Human Factors Awareness Course' for its staff.

If the focus of human factors in World War II was primarily on correcting systems that were obviously faulty, the current phase of thinking is moving to consider the limitation of the human operator prior to building a system so that a more effective allocation of functions can be made between human and system and thus reducing the limitations in both. An early example of this approach was a study undertaken by Fitts and Jones (1947) which described the types of errors being made by pilots through the misinterpretation of instrument information. Today Boeing lead the way with their developments on the 777 series aircraft, but what of the developments in Air Traffic Control?

1.2 The Present

The development of human factors issues within Air Traffic Control (ATC) has advanced a little more slowly than within the pilot performance area. Although the catagorisation of ATC errors in air incidents is not new, the analysis as to their cause has not always been well recognised or researched. Another reason is the low profile of the ATC personnel themselves. Unlike the pilots who are visable to the flying public, Air Traffic Control is less visable and, to many, a mystery. However, perhaps the tragedy which occurred over Zagreb in 1976 changed this. Since this time, and as a result of other air accidents, the performance and the limitations of those in ATC have been scrutinised more closely.

Edwards (1988) has provided a useful definition of human factors. He has suggested

Human factors (or ergonomics) may be defined as the technology concerned to optimize the relationship between people and their activities by the systematic application of human sciences, integrated within the framework of systems engineering, (p.9)

This definition suggests not only that human factors and ergonomics should be regarded synonymously, but that all human sciences should be considered in this relationship. It also implies that those working in these environments are now represented by both genders and that the interaction of these people is just as important as their relationship with the technology they work with. The optimisation of this relationship also suggests two sets of criteria. That is, that the human factors approach must not only be concerned with the level of'well being' of the individual, but also with the effectiveness of the systems performance. Often in the past organisations have been very concerned about the second factor mentioned, particularly as it affects profit, and little about the first.

Before we define, elaborate and investigate each of the aspects mentioned by Edwards throughout the remaining chapters, let us consider the following accident.

1.3 Applied Human Factors in Air Traffic Control

Part One: The Circumstances

In the early hours of an Autumn Monday morning, a twin-engined jet transport with 5 crew members and 63 passengers on board, while in its take-off run at Anyfield Airport collided with a small twin-engined propellor driven aircraft, with a single crew member, that had intruded the departure runway. Both aircraft were severely damaged as a result of the collision. The subsequent fire destroyed both aircraft and was the cause of death for most of the passengers.

Anyfield Airport is a medium sized airport, with a single runway which can be accessed (or vacated) by a number of intersections. It is a controlled aerodrome, the control tower is located 400 metres north of the middle of the runway. Traffic numbers are on the rise as quite a few commuter type airlines have started operating to and from Anyfield, Although the airport is in a region in which several foggy days a year are common, it is not equipped with a Surface Movement Radar (SMR), nor does it have special taxiway lighting facilities for use under low visibility conditions.

Air Traffic Control at Anyfield is slightly understaffed, but thus far it had not been thought necessary to impose restrictions on operations to and from Anyfield. There is a discrete frequency to handle taxiing aircraft 'Groundcontrol'.

At the time of the collision, the average visibility was around 700 metres with fog banks, which was just sufficient to allow the Tower controller to see the middle part of the runway. The controllers' view at the intersection where the intruding aircraft entered the runway however was obstructed by a newly constructed extension to the terminal building at Anyfield Airport. The Air Traffic Control Officer (ATCO) was a very experienced controller. He had been working in Air Traffic Control for many years at several major facilities, and had been transferred to Any field to act as an OJT instructor 8 months before the date of the accident. At the time of the collision, the ATCO was alone in the control tower, as his Assistant/Ground controller (of far less experience) had briefly left the tower to answer a call of nature. They were both completing their third consecutive nightshift, and had come on duty at 22:00 hours the previous evening. They were due to be relieved within 30 minutes when the accident occurred.

The crew of the jet aircraft were experienced operators to and from Anyfield. From their point of view, on the morning of the accident, there was nothing unusual in the way their flight was handled by Air Traffic Control. They taxied to the runway with the extra caution required by the fog conditions, and after being cleared for take-off they made certain they were lined up correctly on the runway centreline before applying take-off power.

The pilot of the twin-engined piston driven aircraft was unfamiliar with Anyfield Airport, having been sent there at short notice to collect an aircraft that had to divert into Anyfield two days earlier for weather reasons.

Part Two: Background Details - The Human Factors

Although the ATCO was very experienced, he had only worked a limited number of solo shifts in Anyfield Tower. Having validated his Tower rating in early summer, he had been involved in giving OJT instruction on most of his shifts since that time. As a consequence of the staff shortage he was required, like all other controllers, to work his share of nightshifts. The shift in which the accident occurred was only his second in which he had worked at Anyfield Tower under foggy/low visibility conditions; the first had been the previous night, when there was hardly any traffic as it was the mid weekend shift.

A number of years ago there had been an incident at Anyfield involving runway intrusion by a vehicle, under similar meteorological conditions as in this case. One of the recommendations at that time was the installation of an SMR, together with stop bars at all runway intersections. The authorities decided that in view of the limited number of days (with fog) that would warrant the use of an SMR, the benefit of having an SMR did not match the costs of having one installed. The same argument applied with regard to the installation of stop bars, but in lieu of those, painted signs had been put in the grass next to the runway intersections, informing those who noticed them there was a "runway ahead".

As the early morning traffic began to increase, the ATCO and his G/C were each working an independent R/T frequency. When the G/C announced he had to visit the men's room for a second, the ATCO told him to go ahead, intending to work both frequencies by himself. In order to do so, the ATCO had to physically move between 2 control positions in the tower that were about 3 metres apart. Anyfield Tower was not equipped with a frequency coupling installation and transmissions on one frequency could not be heard by stations on the other frequency.

The pilot of the piston engined aircraft had arrived in Anyfield late the night before. After a short sleep he went to the airport in order to waste as little time as possible as his company wanted the aircraft back at its homebase as soon as possible. After the minimum of preparation, he went to his aircraft and called Air Traffic Control for approval to taxi to the runway. He obtained the clearance and began taxiing, but soon found himself lost at the foggy, unfamiliar airport. The fact that there were no signs indicating the various taxiway intersections did not help.

The R/T tapes showed that the pilot of the piston aircraft then called G/C (by R/T) and asked for "progressive taxi instructions". G/C replied by asking his position. The pilot said: "I believe I'm approaching Foxtrot intersection", to which G/C answered: "At Foxtrot taxi straight ahead". In fact the pilot had already passed Foxtrot, and should have turned onto the parallel taxiway. The instruction from G/C, though technically correct, caused the pilot to taxi onto the runway where the jet was in its take-off roll. Since the communications to both aircraft took place on different frequencies, neither pilot was aware of what was happening.

After the collision, it took the ATCO several minutes to realise something was wrong. Of course he had not observed the departing jet passing on the section of the runway that was visible to him, but he initially blamed that on the fogpatches and/or being distracted by traffic on the G/C frequency. Apart from the fog, the ATCO was also unable to see the part of the runway where the collision had taken place because of the newly built extension of the terminal building blocking his view. So it was not until he wanted to transfer the departing jet to the next controller (Departure Control) that he became aware things were not as they should be; his transmissions to the jet remained unanswered. His G/C, who returned shortly after the accident, also reported having no contact with the taxiing twin prop. The ATCO then decided to alert the fire brigade, but as he had no idea where to send them, more precious time was lost as the rescue vehicles tried to make their way across the foggy airport. When they finally arrived at the accident site, they found there was little they could do as the wreckage of th...