S1/2009L Ultralight Aviation Safety and its Improvement through Accident Investigation

In a relatively short period of time in 2009 there were more serious accidents in Finnish ultralight aviation than in previous years. As a result, Accident Investigation Board of Finland (AIB) began to investigate five ultralight aviation accidents that occurred in 2009. AIB also wanted to establish whether there were any common contributing factors behind ultralight accidents, minor accidents and serious incidents. The primary aim of this study was to research and analyse the human factors that contributed to the occurrences in ultralight aviation. The study was restricted to class B ultralight incidents that the AIB had investigated between 2000–2009. Another aim of the study was to analyse and assess the significance of accident investigation with regard to improvements in ultralight aviation safety.

The most important research method used in the analysis of the AIB investigation reports on ultralight accidents, minor accidents and serious incidents was the systematic application of the SHELL-model. The research material included altogether 20 investigation reports. To an extent, information in investigation reports was augmented by means of conversations with investigators and the AIB’s archives. The effectiveness of accident investigation on the improvement of ultralight safety was mainly researched through the analysis of AIB’s safety recommendations and by interviewing the recipients of said safety recommendations. The development of the present safety level in Finnish ultralight aviation was also established. A further goal of the study was to establish how ultralight accidents and incidents are being investigated in foreign countries.

Judging by accident investigation reports and conversations with the investigators, it was the pilot’s limited flight experience that contributed to most occurrences. In almost half of the cases the pilot’s poor flying skills and his unsound course of action contributed to the event. Also inadequate aircraft construction or repair skills and unfavourable weather conditions played a role in many occurrences. Other human factors influencing the occurrences included the pilot’s inadequate flight training, an inadequate flight manual, substandard aircraft construction, incorrect aircraft loading and the pilot’s poor skills in using cockpit equipment. In one quarter of the examined cases the immediate cause of the occurrence was a stall at low altitude. The pilot failed to recognise the symptoms of the approaching stall.

On average, ultralight aviation safety improved during the 2000s, on the basis of this study. The research showed that some safety actions concerning ultralight aviation have only been implemented as a consequence of accident investigation. Nearly all safety actions have been implemented as an outcome of accident investigation but there have also been other contributing factors. This being the case, accident investigation has improved ultralight aviation safety. However, it is very difficult to estimate the level of its impact because there are also many other factors that affect the improvement of ultralight aviation safety. In Finland every ultralight aviation accident and serious incident is investigated. Judging by this study, at least one third of the European countries also investigates ultralight aviation accidents and incidents.

S1/2009L Report (pdf, 3.47 Mt)