Part II. Human Factors and AVSEC Technology by Francis G Spranza



FrancisSpranzaBy its very definition, Human Factors is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance.1 Simply put, Human Factors might be defined as the study of designing equipment and devices that fit the human body and coincide with its cognitive abilities.

World War I saw a distinct shift in the focus in aircraft design- moving from the abilities and attitude of the aviator to Human Factors 01the design of his workspace – the aircraft itself.  The shape, size and position of controls, selection of information that needed to be displayed, ease of cockpit movement and a growing understanding of human limitations due to such factors as altitude and visibility led to developing a more ‘user friendly’ work environment for pilots. In short, these early designers sought to create safe and easy to use interfaces between man and machine. As aircraft, airports and aviation as a whole became more complex; designers began to take into account human limitations and capabilities.

During WWII It was observed that fully functional aircraft, flown by the best-trained pilots, still crashed. In 1943, Alphonse Chapanis, a lieutenant in the U.S. Army, showed that this so-called “pilot error” could be greatly reduced when more logical and differentiable controls replaced confusing designs in airplane cockpits. After the war, the Army Air Force published 19 volumes summarizing what had been established from research during the war.2 As a result of this study, the decision making, attention span, situational awareness and physical abilities of the pilot and crew soon became recognized as an important key in the success or failure of system tasks.  Today, this process takes into account the flight crew’s (users) capabilities and limitations – both physically and mentally- in order to ensure that tasks, functions, information and the work environment fit the human user as well as the commercial passenger

Human Factors and Aviation Security

As aircraft and air terminal designs saw a boom in development during the post-WWII ear, the human working environment envisioned for civil aviation security was grossly neglected.  Being seen as a sub –division of safety- of far greater concern in the  day- security came to be seen as little more than balding overweight retirees reading the daily newspaper while seated in a ramshackle  gatehouse at the edge of the aerodrome.  An environment created despite a scientific and historical perspective that clearly demonstrates that ignoring the Human Factors aspects of a work environment is directly correlated to a reduced operational effectiveness.  Yet, as perceived and real threats to airline and air terminal operators increased- aviation security became the focus of planners, decision makers and both airport/airline administrators around the globe.  This newfound attention led directly to the development and adaptation of a host of technologies to combat and prevent Acts of Unlawful Interference against both aircraft and airport operations.

The Advent of new technologies

Today, with our greater understanding of the science behind human factors, the design and development of everyday tools for use in the aviation security environment affects everything from the design of flashlight handles, to mace dispensers, portable communications and response vehicle interiors.  However, perhaps the best examples of the integration of human –machine interactions can be found in the technology of x-ray screening and CBT learning.

Human Factors 02As technologies change to address various threats – from knives and guns to complex binary explosive devices, the integrity of the system and efficiency of the machines in achieving their respective goals remains with the human operator.  A key limiting factor in determining the effectiveness of the screening process is the ability of an operator to correctly recognize and identify threat objects.  Regardless of the degree and quality of automation, studies have shown it is vital to keep the human decision making process in the loop, especially if officers must respond to an abnormal or emergency situation. While today’s x-ray machines  have the ability to enhance, rotate, color, and view in 3D, the ultimate decision to move a bag or piece of cargo through or hold it for further inspection remains the decision of a human operator.

With this in mind, understanding the human psychi and how we process information, our attention spans, logical thinking and ability to recall what we have been taught become critical factors in screener performance.  Successful screener interdiction then is dependent upon:

  1. The technological limitations of the machine
  2. User ergonomics
  3. Operator selection criteria
  4. Training and evaluation methodology

While many older generation x-ray screening machines could detect guns, knives, and unusual shapes within a bag or cargo pallet, they failed to have the advancements needed in order to alert on more complex organic compounds such as modern day explosives.  Newer generation devices incorporated a variety of image enhancement tools such as image manipulation, zoom and magnification, varying penetration levels, organic stripping, contrast control, video rotation and the like.  All designed to assist the human operator in making a valid decision as to the contents of the bag and respective threat or no-threat decision. While these manipulations were and remain helpful, users often were faced with multiple screens, confusing controls and uncomfortably long working periods without considerations of fatigue or boredom.

Studies undertaken by the DERA Centre of Human Sciences through the use of operational trials have uncovered several important Human Factors issues requiring attention. For instance, operators may lack the detailed knowledge of the image enhancement functions available for the enhancement and manipulation of on-screen image. More importantly, they have an apparently limited understanding about the use of the enhancement functions and of the type of image that those functions are useful in exploiting. The use of image enhancement function is also not consistent between different equipment types within and across airports. Operators do not apply any particular criteria in selecting which image enhancement functions are to be used on particular images.3

By definition, Ergonomics derives from two Greek words: ergon, meaning work, and nomoi, meaning natural laws, to create a word that means the science of work and a person’s relationship to that work, 4 applying this definition to the design of aviation security technologies, proper ergonomic design:

  1. Minimizes operator error
  2. Enhances system usability
  3. Matches user/operator to the level of interface – making the technology as a whole more appropriate based on training, physical ability and cognitive level of the user
  4. Matches use with training tasks and instruments

Transferring tasks that are boring, repetitive and time consuming to machines can reduce errors and increase both effectiveness and efficiency when done properly.  It remains important that operators are able to easily see, interpret and manipulate displays and other interactive devices quickly and accurately.

Regardless of the shape, color, placement or amount of information displayed, as noted earlier, the ultimate factor in achieving specific goals and objectives within the AVSEC (Aviation Security) environment rests with the human factor.  Selecting the proper individual for the job is critical, and no amount of technology, add-ons or environmental manipulation can make up for a poorly chosen candidate.

I am reminded of my encounter with a young man operating the one and only x-ray screening machine at an airport in the Caribbean.  Though nice enough in demeanor and sharply attired, he diligently stared at the machine’s color monitor display as bag after carry-on bag passed through.  After the boarding passengers had departed I had an opportunity to speak at length with the office, and came to learn that he was having quite a difficult time with the equipment.  I later learned he was in fact color blind.  Despite his handicap, he was assigned to monitor the x-ray display.

Again, personnel selection is critical to effective and efficient screening operations, or for that matter any security related task.

Each task within the aviation security environment has associated with it a unique set of knowledge, skills and abilities – known as KSA’s.  Each requires cursory background knowledge of the technology involved, means of accessing data and cognitive interpretation of the data presented.  Differing tasks require differing sets of KSA’s as well as varying physical practicum in order for the student to become proficient at the task at hand.

Critical to screener training and useful in a variety of decision making scenarios, CBT or Computer Based Training allows students a virtual ‘real world’ task practicum experience.  Computer interfaces can be made to match the make, model and display of any x-ray or detection device, serving both to familiarize the student with the target positioning options as well as operator selectable controls.  Set in a controlled and monitored environment, students essentially learn by doing.

Human Factors 03Through the introduction of Threat Image Projection (TIP) technology, allowing for the virtual inclusion of threat images into the physically derived image or scanned bag, students can easily be exposed to a variety of decision making situations.  Once in the field, screeners can be randomly evaluated through the introduction of TIP images during routine scanning situations.

Computer based training (CBT) should not be thought of as simply limited to the screening function of aviation security.  CBT in the form of interactive distance learning can present a variety of real world scenarios requiring student intervention, decision making or skill demonstration.  Today’s technology can bring the interactive  learning to the student/trainee in forms ranging from simple true/false questions to complex video game quality programs, utilizing multiple student role players with any number of possible outcomes.  No longer is CBT learning bound to one work station at one location.  The use of smart phones, pads, laptops and mobile devices now means that training can be brought from the classroom to the student regardless of organizational or geographic constraints.


The inclusion of Human Factors considerations within any airport or airline security organization must follow in the design of SMS, SMeS and other forms of Organizational Development.  Implemented on an organization wide scale and with consideration for the agency wide objectives, individual organizational structure and working environment, human factors considerations can greatly enhance the effectiveness of aviation security as a whole.


Original Article can be viewed here:


  1. International Ergonomics Association. What is Ergonomics. Website. Retrieved 6 December 2010.
  2. The History of Human Factors and Ergonomics, David Meister
  3. ICAO Doc 9808/AN765, Section 2.3.4.


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