D. Litt. et Phil. / The influence of the human factor in the causation of accidents no doubt has been recognised from the very origins of humankind. In the words of Cicero "It is in the nature of man to err". Epithets such as 'human error', 'accident prone', 'inattentive', 'clumsy', 'drunk', etcetera form part of our everyday language to ascribe the reasons for accidents. In aviation, the general term 'pilot error' has been used to ascribe the cause of accidents since the time of the first heavier-than-air aircraft flights by the Wright brothers in 1903. The problem with this generalised term is that it offers no insight into why the pilot erred so that training steps may be undertaken to try to avoid the error from recurring – not only for the pilot concerned, but for the entire community. Under the direction of the Federal Aviation Administration (FAA) in the United States in 1976, Jensen and Benel determined that poor pilot decision-making is a significant factor in the causation of accidents in general aviation (Lester, Diehl, & Buch, 1985). These results were corroborated in an analysis of airline and military accidents by Diehl (1991b). The follow up to the Jensen and Benel findings was the development of training manuals by the Embry-Riddle Aeronautical University (ERAU) to address the identified problem. The effectiveness of these manuals in practice was tested empirically in experiments conducted in the U.S.A., Canada, and Australia that showed improvements in pilot decision-making ranging from 8% to 46% (Diehl, 1990). Simultaneously with this work airlines such as KLM and UAL developed their own human factors training programmes, which was the beginning of the significant industry of aviation human factors training. This activity has been supported academically through a bi-annual 'Symposium on Aviation Psychology' held at the University of Illinois since 1981. iv Since the initial verification of the ERAU training programmes, the continued support for aviation human factors training has come mainly from anecdotal evidence of its success in assisting pilots to avoid accidents. There is a paucity of experimental evidence to support this dynamic activity. Evidence for this is illustrated from the intense and extensive debate on the Crew Resource Management website (crmdevel@ yahoogroups.com) in 2001/2 on the topic "CRM – is it working?" Despite the widely accepted and even legislated (by the International Civil Aviation Organisation) application of aviation human factors training for pilots, this activity has been slow to filter through to other aviation activities. For example it was introduced into the South African air traffic control community for the first time only in 2001. With the introduction of this training the opportunity arose to develop a practical means to assess its effectiveness. This research study outlines the basis on which the developed assessment method has been achieved. The research method followed in the study is the Design and Development model of Thomas and Rothman (1994a). The disciplined approach to intervention development in the human sciences that the model demands, ensures that the parameters for the successful development of the intervention are clearly established in advance of its application, so that its validity can be assessed on an acceptable academic basis. It is confidently anticipated that the assessment questionnaire and the recommended procedures for its implementation will demonstrate whether or not human factors training (team resource management training [TRM training]) is effective in improving the attitudes and performance of air traffic controllers. A secondary outcome of this research project is the development of a TRM training manual for South African air traffic controllers and the measurement of the empirical results of this training. These results indicate positive acceptance, learning, and attitudinal changes as a result of the implementation of the training programme.