A very interesting article from Flight International by David Learmont published 5 January 2009
Well worth reading the whole article, but some of the key messages are summarised below.
Wilbur Wright wrote to his father: "In flying I have learned that carelessness and overconfidence are usually far more dangerous than deliberately accepted risks." Whilst, in the 1930s First World War pilot Capt A G Lamplugh described of the risks of flying as "Aviation in itself is not inherently dangerous. But to an even greater degree than the sea, it is terribly unforgiving of any carelessness, incapacity or neglect." Both had clearly learnt that no activity can be completely risk-free, but that risk should be managed so as to remain within acceptable bounds.
Most safety lessons are learnt through experience. Father of the Flight Safety Foundation Jerry Lederer said in 1939 that "strange as it may seem, a very light coating of snow or ice, light enough to be hardly visible, will have a tremendous effect on reducing the performance of a modern airplane". The challenge has always been to disseminate learning. In January 2002 a Bombardier Challenger 604 business jet at crashed on take-off from Birmingham. It had been left on the ramp overnight and not de-iced before take-off was attempted.
Airframes, engines and aircraft systems have continually become stronger and more reliable, but as these improved the aircraft could also fly faster, perform a greater variety of tasks, and operate in worse weather conditions.
As the machinery became more reliable it caused less accidents. The role of the human became the focus of those who would improve aviation safety, really staring in the 1970s covering both on-board crew and maintenance.
Cockpit or flightdeck ergonomics started to improve in the 1960s, and really stepped up in the 1980's when cathode ray tube instrument displays (later replaced by liquid crystal displays) started to appear. This provided opportunities to improve crew situational awareness because data regarding performance and navigation could be integrated rather than being displayed as disparate pieces of data. This not only reduced the potential for individual confusion, but provided both pilots with the same picture of what was going on rather than allowing each to develop their own pictures that may not be identical.
In the 1970s KLM invented the concept of crew resource management (CRM) with the objective of improving the way crew communicated and worked together. This is now officially accepted globally as a critical part of multi-crew pilot training.
Technology alone has rarely eliminated a serious risk, but since the mid-1990s real progress has been made in reducing what had been the worst killer accident category - controlled flight into terrain. The ground proximity warning system (GPWS) has been replaced by Enhanced GPWS (EGPWS) which provides pilots with a graphic picture of their position and height relative to terrain, plus audio alerts. It is stated that there have been no incidents of controlled flight into terrain involving aircraft fitted EGPWS, but 5% of the world's big jet airline fleet that do not have it.
The windshear alert was developed in the late 1980s after meteorologists improved their understanding of phenomena such as windshear and microbursts associated with storm cells, and how these can affect aircraft close to the ground just after take-off and on approach. Pilots' awareness of the risk has also been improved.
Information technology has allowed company and global databases of safety data to be developed. Downloading data from aircraft allows engineers to recognise where operational best practice has been breached and to spot the technical signs of impending equipment failure.
In addition, the adoption of safety management systems and global auditing of airlines has made its contribution. But it may be argued that liberalisation of the market has allowed greater competition and therefore greater passenger choice. Where there is a choice of another airline to fly with, a carrier that has suffered an accident also suffers commercially.