57TH ANNUAL CONFERENCE, Accra, Ghana, 19-23 March 2018
WP No. 162
HF Considerations when Operating Multiple Operational Positions/Sectors
Presented by PLC
Why are human conditions, such as fatigue, complacency, and stress, so important in aviation? These conditions, along with many others, are called human factors. Human factors directly cause or contribute to many aviation accidents and incidents. It is universally agreed that 80 percent of errors involve human factors. If they are not detected and acted upon, they can cause safety events and even accidents.
1.1. Air Traffic Control operations impose a demand on a controller’s mental workload. It has already been noted that the projected increase in air traffic over the next decade threatens to overwhelm the capacity of the air transportation system. If safety is not to be compromised, it is vital that individual controllers are not subjected to overload due to high traffic density and complexity.
1.2. Most Air Navigation Service Providers (ANSP’s) are looking for ingenious ways to save money and reduce labour costs in a safe responsible way. At this stage labour cost is an ever-souring expense for most ANSP’s in the world and the one thing ANSP’s would like to reduce dramatically. One of the ways is working multiple sectors, either combined into one or working two or more positions shifting between workstations or airports in the process. An eye-opening illustration of this practice is the Überlingen mid-air disaster where this was one of the contributing factors.
1.3. This paper will attempt to look at simultaneous manning of Multiple Operational Positions/Sectors by one person, either combined or individually shifting focus between two areas of responsibilities and the Human Factors (HF) considerations affecting it. We will look at a broad overview of HF and what it consists of. We will then discuss the HF Considerations when working multiple operational positions.
2.1.1. There is no recognised definition that could be found on Multiple Operational Positions/Sectors currently. For the purpose of this paper a definition could be of great help to define the scope of these terms.
2.1.2. Multiple Operational Positions is defined as:
184.108.40.206. Situation where two or more independent working positions would be manned and monitored by one operational controller, switching from one task to another. This could be two or more Terminal Control Units (TCUs) on two different display screens controlled and monitored by one operational controller or controlling two or more Remote Tower Operations (RTO) by one operational controller in a remote or virtual centres.
2.1.3. Multiple Operational Sectors is defined as:
220.127.116.11. Situation where two or more independent sectors is combined to one sector manned and monitored by one operational controller on one working position.
2.2. IFATCA Policy
2.2.1. IFATCA Policy is clear on Remote and Virtual Towers and what IFATCA requires from developers and ANSPs when developing and operating this new advanced technology.
18.104.22.168. IFATCA Policy is:
|ATCOs shall not be required to provide a Remote and Virtual tower service for more than one aerodrome simultaneously.|
22.214.171.124. IFATCA Policy is:
|Separation standards and procedures for Remote and Virtual Towers shall be developed or adapted and implemented based on a robust safety case and the demonstrated capabilities of the system.|
126.96.36.199. IFATCA Policy is:
|Standards, procedures and guidance for Remote and Virtual Towers are required.|
188.8.131.52. IFATCA Policy is:
|Remote and Virtual tower systems should be capable of providing the same service level as an aerodrome control tower; partial aerodrome control service configurations are undesirable.|
184.108.40.206. IFATCA Policy is:
|Provisions, training programmes, separation standards and a specific Remote Tower endorsement are required for operating at Remote and Virtual Towers.|
2.2.2. IFATCA Policy regarding Single Person Operations (SPO) and Lone Person Operations (LPO) is clear and that the 4 Eyed Principal is supported by IFATCA. There is also good Policy on Virtual Centres and Functional Airspace Blocks.
220.127.116.11. IFATCA Policy is:
|Single or Lone Person Operations (SPO/LPO) shall be avoided. The use of SPO/LPO should be strongly discouraged by MAs, both through ANSP and their regulator.
If providers choose to operate SPO/LPO, they shall bear the responsibility for the resulting risk(s) to the system.
If SPO/LPO occurs, appropriate measures shall be taken to ensure that the SPO/LPO situation changes to another manning scenario. Until such time, measures shall be taken to mitigate all impacts of SPO/LPO, such as, but not limited to traffic regulation, work break provisions, informing neighbouring ATC units. Procedures shall be in place to implement such measures in an efficient way, not increasing the workload of the ATCO.
18.104.22.168. IFATCA policy is:
|Implementation of 4EP shall be strongly encouraged by MAs, both through their ANSP(s) and their regulator(s).
An ATCO shall not be held liable for incidents or accidents resulting solely or in part from the non-implementation of the 4EP safety net.
22.214.171.124. IFATCA policy is:
|ATM data must be of sufficient quality, reliability and integrity for its intended use.
Organisations that provide ATM services beyond state borders shall clearly define the operational legal implications of providing these services, and train controllers in the implications.
The efficient creation and management of an FAB does not necessarily require the physical concentration of all ANS functions within a single centre.
Consideration shall be given to the personal and social implications for controllers associated with the relocation and/or consolidation of ATS units.
Consolidation of ATS units, whether virtual or physical, shall be considered equal to the implementation of a new ATM system.
2.3. Human Factors
2.3.1. The term human factors has grown increasingly popular as the commercial aviation industry realise that human error, rather than mechanical failure, underlies most aviation accidents and incidents. Human factors science or technologies are multidisciplinary fields incorporating contributions from psychology, engineering, industrial design, statistics, operations research, and anthropometry. It is a term that covers the science of understanding the properties of human capability, the application of this understanding to the design, development, and deployment of systems and services, and the art of ensuring successful application of human factor principles into the air traffic control working environment.
2.3.2. The study of Human factors (HF) is about understanding human behaviour and performance. It involves applying scientific knowledge about the human body and mind to help understand human capabilities and limitations. Human Factors incorporates matters affecting how humans do their jobs. They are the social and personal skills, such as communication and decision making which complement their technical skills.
2.3.3. A key principle of human factors approaches is that elements operate within systems. A system is a set of interdependent elements that work together to achieve a goal. To understand how systems perform, it is important to examine the individual system elements and the interactions between those elements.
2.3.4. According to the International Ergonomics Association, there are three broad domains of ergonomics or human factors as we know it:
- Physical Domain;
- Cognitive Domain;
- Organisational Domain.
2.3.5. ATM Functional Systems can be divided into five elements and is based on the PETE factors model:
2.3.6. This model can be extended to include the external environment and the process of system adaptation.
2.3.7. A principle of systems is that a change to one element affects other elements and alters the system’s behaviour. Thus, merely focusing on one element of the system, such as implementing an electronic flight progress strips without considering other system elements and interactions between the elements, will not improve safety overall.
2.4. Physical Domain
2.4.1. The physical domain focuses on how the human body and physical activity interacts with work design, for example:
- The layout of the Air Traffic Control facility should promote team communication and situational awareness whilst reducing distractions;
- The location of the work station in the operational room in relation to the air traffic controller and supporting staff;
- Working Postures;
- The size of the display screen and character font (colour and size);
- The design of tools/equipment used by the controller and support staff;
- Repetitive movements;
- Safety and health.
2.4.2. An Air Traffic Controller controlling Multiple Operational Positions would be severely compromised, having to move from one screen to another (TCU’s) or switching from one aerodrome to another (RTO). The moving between screens (TCU’s) or switching between airports (RTO) is strongly opposed by IFATCA.
2.5. Cognitive Domain
2.5.1. The Cognitive domain focuses on mental processes, such as perception, memory, reasoning, and motor response, as they affect interactions among humans and other elements of a system. A comprehensive paper on Cognitive Processes in Air Traffic Control (WP C.6.2) was presented in Las Vegas in 2016.
- Mental workload;
- Skilled performance;
- Human-computer interactions;
- Human reliability;
- Work stressors affecting Air Traffic Controllers.
2.5.2. Air Traffic Control has a high mental and decision making workload in a normal operating environment, adding Multiple Operational Positions to this workload may have a detrimental effect on safety and should not be allowed in any circumstance.
2.6. Organisational Domain
2.6.1. The organisational domain focuses on how individuals and teams interact with tools, technologies, their organisational structures, policies and processes, for example:
- Crew resource management;
- Work design;
- Design of working times;
- Participatory design;
- Community ergonomics;
- Co-operative work;
- New work paradigms;
- Quality management;
- The Clarity of an air traffic controller’s roles and job design;
- The Communication and sharing of information between controllers and other stake holders;
- Controlling Policies and Procedures.
2.6.2. The policy and procedures regulating Air Traffic Control and how Air Traffic Controllers should work must be clear at all times. These procedures should include all Organisational influence and restrictions, staff shortages and combining of sectors / positions in a safe acceptable manner onto one operational screen.
2.7.1. Workload is one of the riskiest aspects in Air Traffic Control and more so with multiple operational sector / position operations. It should be noted at the outset that the entire range of controller workload, from low to high, needs to be considered in air traffic control operations. It is most natural to think of high levels, or overload, when considering workload. Considerable evidence exists to indicate that human operators who experience high levels of workload can be susceptible to errors or performance breakdown. A study by Endsley and Rodgers (1996), for example, appeared to demonstrate a positive correlation between workload and operational errors, at least for high levels of workload. However, underload can be equally unsafe. Hopkin (1995) suggested that the extensive research on overload in air traffic control has led to a relative neglect of underload, operational errors have also been reported under conditions of low to moderate traffic complexity (Stager, 1991; Stager and Hameluck, 1990). Thus, it is important to understand both underload and overload, including the ways in which situation awareness mediates the relationship between workload and errors.
2.7.2. Another point worth noting is that there is no typical controller workload profile or characteristic style of vigilance that is representative of air traffic control in general. Workload patterns and the quality of vigilant monitoring are likely to differ between EnRoute, Approach, and Tower Controllers, between control centres of different levels, between radar and procedural control, between different sectors, and so on. Ultimately any comprehensive examination of the workload of air traffic control must be stratified by these and other job- and system-related factors.
2.7.3. It is worthwhile to remember that consideration of physical workload may still be necessary on occasion. Even in the most information-intensive job, the human operator must interact physically with devices to exchange information. The placement and control features of these input and output devices, if poorly designed, may not only lead to injury (e.g. carpal tunnel syndrome) but also induce discomfort and fatigue. Furthermore, to the extent that the physical demands imposed on controllers (e.g. keyboard entry, movement of flight strips, reaching, and other manual behaviours) interact with cognitive activities and therefore contribute indirectly to mental workload, consideration of the physical workload is important.
2.8. Task switching not Multi-Tasking
2.8.1. The term multi-tasking is a misnomer. Humans can’t do more than one task at a time. Instead we switch tasks. So the term that is used in research is “task switching”.
2.8.2. Task switching is “expensive” — There has been a lot of research on task switching. Here’s what we know from the research:
- It takes more time to get tasks completed if you switch between them than if you do them one at a time.
- You make more errors when you switch than if you do one task at a time.
- If the tasks are complex then these time and error penalties increase.
- Each task switch might waste only 1/10th of a second, but if you do a lot of switching in a day it can add up to a loss of 40% of your productivity.
- Task switching involves several parts of your brain: Brain scans during task switching show activity in four major areas: the pre-frontal cortex is involved in shifting and focusing your attention, and selecting which task to do when. The posterior parietal lobe activates rules for each task you switch to, the anterior cingulate gyrus monitors errors, and the pre-motor cortex is preparing for you to move in some way.
2.8.3. It’s popular to think that you are multi-tasking, but the research is clear that humans can’t multi-task, with one specific exception that I’ll get to in a minute.
2.8.4. For many years, the psychology research has shown that humans can only attend to one task at a time. More specific, the research shows that humans can attend to only one cognitive task at a time. You can only be thinking about one thing at a time or You can only be conducting one mental activity at a time.
2.8.5. We are pretty good at switching back and forth quickly, so we THINK we are actually multi-tasking, but in reality, we are not.
2.8.6. The only exception that the research has uncovered is that if you are doing a physical task that you have done very often and you are very good at, then you can do that physical task while you are doing a mental task. So if you are an adult and you have learned to walk then you can walk and talk at the same time.
2.8.7. Even this doesn’t work very well, though. In a study by Hyman et. al. in 2009, humans talking on their cell phones while walking, ran into other humans more often and didn’t notice what was going on around them. The researchers had someone in a clown suit ride a unicycle. The individuals talking on a cell phone were much less likely to notice or remember the clown.
2.8.8. A study at Stanford University demonstrates that multi-tasking doesn’t work, even with college students. Clifford Nass’s study found that when humans are asked to deal with multiple streams of information they can’t pay attention to them, can’t remember as well, and don’t switch as well as they thought they would – even college students.
2.8.9. Air Traffic Controllers are master task switchers, we prioritise the most important tasks first and we work through the list at lighting speed. Air Traffic Controllers has acquired the ability to concentrate for prolonged periods of time due to the requirements of the job. But we do not multi-task and we still do make errors. The more pressure the ATC System puts on the Controller to perform at unacceptable high levels of task switching the more unsafe the system will become.
3.1. Most Air Navigation Service Providers (ANSP’s) are looking for ingenious ways to save money and reduce labour costs in a safe responsible way. One of the ways is working multiple sectors either combined into one or working two or more positions shifting between workstations or virtual airports in the process.
3.2. A key principle of human factors approaches is that elements operate within systems. A system is a set of interdependent elements that work together to achieve a goal. A principle of systems is that a change to one element affects other elements and alters the system’s behaviour.
3.3. An Air Traffic Controller controlling Multiple Operational Positions would be severely compromised, having to move from one screen to another (TCU’s) or switching from one aerodrome to another (RTO). The moving between screens (TCU’s) or switching between airports (RTO) is strongly opposed by IFATCA.
3.4. Workload patterns and the quality of vigilant monitoring are likely to differ between EnRoute, Approach, and Tower Controllers, between control centres of different levels, between radar and procedural control, between different sectors, and so on.
3.5. The term multi-tasking is a misnomer. Humans cannot do more than one task at a time. Instead we switch tasks, so the term that is used in research is “task switching”. Air Traffic Controllers are master task switchers but we do not multi-task and we still do make errors. The more pressure the ATC System puts on the Controller to perform at unacceptable high levels of task switching the more unsafe the system will become.
It is recommended that:
4.1 That this paper be accepted as information.
Meyer, D. E., Evans, J. E., Lauber, E. J., Gmeindl, L., Rubinstein, J., Junck, L., & Koeppe, R. A. (1998). The role of dorsolateral prefrontal cortex for executive cognitive processes in task switching. Journal of Cognitive Neuroscience, 1998, Vol. 10.
Meyer, D. E., Evans, J. E., Lauber, E. J., Rubinstein, J., Gmeindl, L., Junck, L., & Koeppe, R. A. (1997). Activation of brain mechanisms for executive mental processes in cognitive task switching. Journal of Cognitive Neuroscience, 1997, Vol. 9.
Last Update: October 1, 2020