Competing Discourses in Aircraft Cabin Air Contamination: How to Define a Problem

In the scientific literature and in the media there is a growing concern about toxins in aircraft originating from the air conditioning system as a result from pyrolised jet engine and hydraulic oil, and more recently also de-icing fluid. Many crews have reported long-term neurological and respiratory health effects, but also acute impairment or even incapacitation while performing their flight duties. Several incident reports described that pilots had cognitive impairments that interfered with flight safety. Numerous incident/accident and technical investigations have revealed oil leaks, after crew reported such impairments. Engine and hydraulic oils contain known neurotoxins, which are suspected to cause these impairments. Single-case investigations and summary reports have repeatedly defined this as a threat to flight safety. Nevertheless, there are diverging views on the actions that are needed. Pilots have no warning or detection systems to either identify or dismiss a contaminated bleed air event, although it is a requirement that warning devices should be installed to warn pilots for any unsafe situation that needs corrective action. This unsettles crews in their decision-making and produces diversion costs for airlines in the case of false negatives when the only possible reaction is a diversion landing. The aim of this study is to deliver a more abstract definition of the problem space, by analysing the issue of cabin air contamination not only by its final effects, but also by the complex interactions that are involved when accepting the identification problems for crews and incident investigators. This thesis will explore some reasons behind the competing discourses on flight safety, but also investigate the mechanisms that enable such divergent interpretations and which effects are further created by it. The central question is which signals the system has generated in relation to cabin air contamination and how the effects of contaminated bleed air on aircraft have been interpreted and defined