According to industry folklore, aircraft design was the product of engineers who cared passionately that their creations worked well, but did not give undue thought to those who would operate and maintain them.
New equipment which brought operational advantage in some form tended to be accepted, not only for that advantage but because its very newness meant that there were no terms of reference against which the certificators could judge it.
It has become clear that a more enlightened approach to certificating new equipment - including software - is needed, but it has not been easy to devise the guiding parameters for certificators. Now, following years of joint work by the European Joint Aviation Authorities and the US Federal Aviation Administration, design guidelines are emerging, and the certification of the Fairchild Aerospace 728JET in 2002 is expected to be the first to be tested under the new system.
Under the traditional method, once the engineers had designed a new aircraft it was put through its paces by test pilots. These are aviators of above average ability who would not be in their jobs if they did not have a certain empathy with engineers and engineering. Provided they could master the aircraft and its equipment, they might, for example, order a stall warning system to be installed to aid ordinary pilots with lower levels of skill, and then award the certificate.
The early application of ergonomics to aviation meant little more than checking that the pilot could reach the appropriate levers and buttons without physical contortions. Ergonomics remains important, but now cockpit designers are expected to do more. They are invited to analyse what mistakes could be made by a pilot while using new equipment, then to redesign it so that those mistakes are less likely, and to ensure that the consequences of possible errors are not serious.
The motivation to make errors less likely - and less disastrous when they occur - derives from the fact that human error remains a causal factor in the majority of serious aircraft accidents, which makes it the most fertile area in which work can be done to cut accident rates. The dawning of awareness that safety agencies and the operators themselves needed to take a greater responsibility for monitoring equipment design stems back to US military experience with contractors during the Vietnam war.
Soldiers were issued with equipment packs that were too heavy to carry, and weaponry so complex that it was beyond the ability of soldiers to use it without massively expanded training. Basically, the human part of the system was not being given enough consideration.
"Man-machine interface" and "human-centred engineering" have become design buzzwords - and phrases - in common currency since the late 1980s. Avionics and the cockpit are first in line for the certificators' attention under this more enlightened form of design scrutiny, but it will gradually be applied to component manufacture with maintenance engineers in mind.
The area of human factors study which is attempting to set the guiding parameters for designers is human hazard analysis. For any new component it examines ease of use, the effects of error during use, task distribution, and the adequacy of feedback to the user in terms of his ability to recognise quickly if the desired result of his actions have not been achieved.
It is the regulators and certificators who have been analysing human error who have enabled this new approach to design to be developed into workable guidelines, but it is up to manufacturers themselves to put it into practice. For the first time, specialist industrial psychologists are going to be on the aircraft and equipment certification teams. If the manufacturers do not want to be continually sent back to the drawing board they are going to have to put the pilot at the centre of their thinking, despite the increasing automation of cockpits. Not just, as in the recent past, to enable a smaller crew to do more with less physical effort.
Now pilots must be given cockpits in which they will make fewer equipment-led mistakes, and to be able to recognise an error as soon as they make it.
Source: Flight International
