Text-only reference. Published from the recorded official FAA General Chapter 14 PDF. Diagrams, photographs, and figure artwork are not reproduced here; use the official FAA PDF for those materials.
14-7 anthropometric drawings. for man. their practical airplane and flight control concepts, many of which are still in use today. Prior to World War I, the only test of human to machine compatibility was that of trial and error. If the human functioned with the machine, he was accepted, if not he was rejected. There was a significant change in the concern for humans during the American Civil War. The U.S. Patent Office was concerned about whether the mass-produced uniforms and new weapons could be used effectively by the infantry men.
Evolution of Maintenance Human Factors
With the onset of World War I (1914–1918), more sophisticated equipment was being developed and the inability of personnel to use such systems led to an increased interest in human capability. Up to this point, the focus of aviation psychology was on the pilot, but as time progressed, the focus shifted onto the aircraft. Of particular concern was the design of the controls and displays, the effects of altitude, and environmental factors on the pilot. The war also brought on the need for aeromedical research and the need for testing and measurement methods. By the end of World War I, two aeronautical labs were established, one at Brooks Air Force Base, Texas, and the other at Wright Field outside of Dayton, Ohio.
Another significant development was in the civilian sector, where the effects of illumination on worker productivity were examined. This led to the identification of the Hawthorne Effect, which suggested that motivational factors could significantly influence human performance. With the onset of World War II (1939–1945), it was becoming increasingly harder to match individuals to pre-existing jobs. Now the design of equipment had to take into account human limitations and take advantage of human capabilities. This change took time as there was a lot of research still to be done to determine the human capabilities and limitations. An example of this is the 1947 study done by Fitts and Jones on the most effective configuration of control knobs to be used in aircraft flight decks. Much of this research transitioned into other equipment with the aim of making the controls and displays easier for the operators to use.
Unfortunately, all the “lessons learned” in the WWII studies of group dynamics, and flight crew communication were seemingly forgotten after the war. Post WWII aircrew studies continued to focus primarily on flight crews, especially pilot selection, simulator training, and cockpit layout and design. Subsequent studies of the technician focused on individual competency and included equipment design (ergonomics). The Vietnam Conflict brought the quest for greater safety, and with that, came a systematic approach for error reduction. This increased attention brought both good and bad changes. It led to the “Zero Defects” quality programs in maintenance and manufacturing. Generally, this had a positive effect.
However, it also led to “crackdown programs” which were one-way communication from management (the infamous “my way or the highway” approach). This concept is more 14-8 over the dunes at Kitty Hawk with their Wright Flyer. dictatorial than democratic, and typically had a long-term negative effect on the company. This “crackdown” approach for behavior control is based upon fear and punishment, which creates a problem. Errors are driven into hiding, and then become apparent later, usually at a more critical time (“Murphy’s Law”). Additional attempts to develop “foolproof” equipment designs were added to the zero-defect manufacturing goal and began to find recognition in the maintenance world as well. Subsequent efforts focused on effects of positive rather than negative motivators. The results of this effort were a reversal of the “crackdown” method, and motivation due to increased morale often improved maintenance safety performance. Studies have shown that motivation resulting from negative sources seldom achieved the same effect. This led to a “Participative Management” style recognized by some U.S. industry and a few airlines, but did not reach maintenance operations until much later.
The Airline Deregulation (1978 –1988) effort had a profound effect upon the aviation community. Prior to 1978, the airline industry was regulated by the Civil Aeronautics Act of 1938. This resulted in peaceful markets, stable routes, and consistent air fares. However, there was a downside consisting of two major problems: wasteful management practices and excessively high wages compared to other comparable skilled-labor industries. The Airline Deregulation Act brought in competitive business practices, with routes and fares controlled by their profitability. This led to a new style of airline management in which a CEO was more of a business person and less knowledgeable of aviation. Existing airlines developed new routes and added new kinds of service and style. Start-up airlines brought other innovative ideas.
The numerous mergers and acquisitions added an increasing pressure to focus on the financial bottom line. Doing more with less became the byline. In the 1980s, maintenance departments were not immune to the pressures of mergers and staff reductions. However, fleets were extremely reliable at that time, and significant savings were aided by a reduction in number of maintenance technicians. Other new ways of conducting business included leasing of aircraft and outsourcing of maintenance. A result of deregulation was change for the maintenance programs (both personnel and departmental) and the pressure to produce and adjust.
The problem, however, was that human factors for aviation maintenance was still stuck in the 1960s model.