World War II and the Birth of Human Factors Engineering

During World War II, human factors was pushed into even greater prom­inence as a science. During this wartime period of rapidly advancing military technology, greater demands were being placed on the users of this technology. Success or failure depended on such factors as the operators’ attention span, hand-eye coordination, situational awareness, and decision-making skills. These demands made it increasingly chal­lenging for operators of the latest military hardware—aircraft, tanks, ships, and other complex military machinery—to operate their equip­ment safely and efficiently.[316] Thus, the need for greater consideration of human factors issues in technological design became more obvious than ever before; as a consequence, the discipline of human engineer­ing emerged.[317] This branch of human factors research is involved with finding ways of designing "machines, operations, and work environ­ments so that they match human capacities and limitations.” Or, to put it another way, it is the "engineering of machines for human use and the engineering of human tasks for operating machines.”[318]

During World War II, no area of military technology had a more critical need for both human factors and human engineering consid­erations than did aviation.[319] Many of the biomedical problems afflict­ing airmen in the First World War had by this time been addressed, but new challenges had appeared. Most noticeable were the increased phys­iological strains for air crewmen who were now flying faster, higher, for longer periods of time, and—because of wartime demands—more aggressively than ever before. High-performance World War II aircraft were capable of cruising several times faster than they were in the pre­vious war and were routinely approaching the speed of sound in steep dives. Because of these higher speeds, they were also exerting more than enough gravitational g forces during turns and pullouts to render pilots almost instantly unconscious. In addition, some of these advanced air­craft could climb high into the stratosphere to altitudes exceeding 40,000 feet and were capable of more hours of flight-time endurance than their human operators possessed. Because of this phenomenal increase in aircraft technology, human factors research focused heavily on address­ing the problems of high-performance flight.[320]

The other aspect of the human factors challenge coming into play involved human engineering concerns. Aircraft of this era were exhibiting a rapidly escalating degree of complexity that made flying them—particu­larly under combat conditions—nearly overwhelming. Because of this com­bination of challenges to the mortals charged with operating these aircraft, human engineering became an increasingly vital aspect of aircraft design.[321]

During these wartime years, high-performance military aircraft were still crashing at an alarmingly high rate, in spite of rigorous pilot train­ing programs and structurally well-designed aircraft. It was eventually accepted that not all of these accidents could be adequately explained by the standard default excuse of "pilot error.” Instead, it became apparent that many of these crashes were more a result of "designer error” than operator error.[322] Military aircraft designers had to do more to help the humans charged with operating these complex, high-performance aircraft. Thus, not only was there a need during these war years for greater human safety and life support in the increasingly hostile environment aloft, but the crews also needed better-designed cockpits to help them perform the complex tasks necessary to carry out their missions and safely return.[323]

In earlier aircraft of this era, design and placement of controls and gauges tended to be purely engineer-driven; that is, they were constructed to be as light as possible and located wherever designers could most conveniently place them, using the shortest connections and simplest attachments. Because the needs of the users were not always taken into account, cockpit designs tended not to be as user-friendly as they should have been. This also meant that there was no attempt to standardize the cockpit layout between different types of aircraft. This contributed to longer and more difficult transitions to new aircraft with different instrument and control arrangements. This disregard for human needs in cockpit design resulted in decreased aircrew efficiency and perfor­mance, greater fatigue, and, ultimately, more mistakes.[324]

An example of this lack of human consideration in cockpit design was one that existed in an early model Boeing B-17 bomber. In this air­craft, the flap and landing gear handles were similar in appearance and proximity, and therefore easily confused. This unfortunate arrangement had already inducted several pilots into the dreaded "gear-up club,” when, after landing, they inadvertently retracted the landing gear instead of the intended flaps. To address this problem, a young Air Corps physiologist and Yale psychology Ph. D. named Alphonse Chapanis proved that the incidence of such pilot errors could be greatly reduced by more logical control design and placement. His ingeniously simple solution of mov­ing the controls apart from one another and attaching different shapes to the various handles allowed pilots to determine by touch alone which control to activate. This fix—though not exactly rocket science—was all that was needed to end a dangerous and costly problem.[325]

As a result of a host of human-operator problems, such as those described above, wartime aircraft design engineers began routinely working with industrial and engineering psychologists and flight sur­geons to optimize human utilization of this technology. Thus was born in aviation the concept of human factors in engineering design, a disci­pline that would become increasingly crucial in the decades to come.[326]