Case Study - Aircraft Safety

Improving aircraft safety in icing conditions

Professor Frank Smith (UCL Mathematics) et al.

The accumulation of ice on forward-facing parts of aircraft (icing) when flying through cloud at or below freezing temperatures has been a significant factor in a number of incidents and accidents, some of which resulted in the loss of life. Icing occurs when supercooled water droplets suspended in the cloud come into contact with the body of the aircraft and freeze onto it. Following a number of accidents, the European Aviation Safety Agency (EASA) proposed an update to their aircraft icing regulations in 2011. Since then, aircraft manufacturers have been working to ensure their designs meet these specifications.

Whilst mathematical models predict reasonably accurately the shape and quantity of ice produced when droplets are small, the quality of these predictions is typically lower for larger droplets. Partly because larger droplets tend to splash, these models have traditionally been prone both to dramatically over-predicting the amount of ice produced and wrongly predicting its location, resulting in errors in forecasting aerodynamic performance and safety.

Between 2001 and 2013, researchers in UCL's Department of Mathematics investigated and modelled various aspects of aircraft icing, taking larger droplets into account to improve the accuracy of the models. Findings included the first-ever predictions of surface roughness effects after impact and of the amount of the water layer splashed away. Some of the work was done in collaboration with the Mathematical Institute in Oxford, the University of Nottingham and the University of East Anglia, who had arrived simultaneously at the same research conclusions.

Collaborations including the EPSRC-funded Knowledge Exchange Programme facilitated the subsequent use of the research by AeroTex, an aircraft icing consultancy whose customers include several aircraft manufacturers and Tier 1 (the top approved) equipment suppliers. AeroTex's use of UCL's research to support its specialist icing work has enabled their customers to operate aircraft more safely in icing conditions and to comply with improved safety legislation.