The Kegworth Air Accident (1989) - Foundations for Designing User-Centered Systems - page 404

within the system. We pick out examples of several types of these below. Rather
than providing an exhaustive analysis (which you can find by reading the accident
report in full, and consulting the many papers that have been published about the
accident), our intention is to illustrate the points of particular interest. We start at a
level that is some distance away from the point at which people are interacting
with technology, as a way of highlighting the importance of understanding the
wider context in which people make decisions and take actions. When you have
finished reading the topic, you should be able to come back to the accident
description above and identify further examples (this is Exercise 14.4).
Regulatory Level Issues
The B737-400 was fitted with a new type of engine. As with all aircraft engines, it
had to undergo extensive testing before it could be certified for operational use.
The engine in this case was a variant of an existing engine (which is common
practice in the aero-engine industry), and it was thoroughly tested on the ground
before being certified by the FAA (and ratified by the CAA). The engine was not,
however, tested either in an altitude test cell (which simulates the conditions of
flying at high altitudes) or in flight. If it had been so tested, this may have
highlighted the fact that there was a flaw in the design which led to a turbine blade
failure under certain patterns of vibration. This scenario illustrates how decisions
that are made at remote distance from the user interface in a system can have an
impact on the way that the users behave. If the engine had still been certified, and
both the airline and the flight crew had known that this was a potential (even if
very rare) problem, they could have included a checklist to deal with it in the
Quick Reference Handbook (QRH) that is used by all pilots to deal with known
situations, such as smoke in the cockpit.
Organizational Level Issues
The B737-400 was what is known as a glass cockpit aircraft, in which the
information is presented on digital displays rather than the vast array of analogue
instruments and electro-mechanical displays that appeared in the cockpit of its
predecessor, the B737-300. The airline (BMA) did not have a glass cockpit flight
training simulator for the B737-400, so pilots could only gain experience in using
the new glass cockpit when they were actually flying it (i.e., on the job). The only
training the pilots were given about the B737-400 was a 1-day audio-visual
conversion course.
ATC offered the pilots two places to land. On company instructions, they chose to
land at East Midlands airport, which was on their flight path, and the closest airport.
This reduced the amount of time that they had available to reflect fully on the
decisions and actions taken so far to deal with the engine problems. While the pilots