This Data Item demonstrates the application of an empirical model to determine the depth of a layer of contaminant that is covering a runway surface@ based on the resistive forces that are measured by a ground-test machine that comprises a free-rolling wheel and a braked wheel. The contaminants considered are water@ slush@ loose snow and ice. The Data Item forms part of a series of Data Items which outline application of the empirical model that is defined in ESDU 10015@ Model for performance of a single aircraft tyre rolling or braking on dry and precipitate contaminated runways@ and summarised in ESDU 05011@ Summary of the model for performance of an aircraft tyre rolling or braking on dry or precipitate contaminated runways. Background information relating to the application of the model is given in ESDU 10002@ Introduction to worked examples of tyres rolling or braking on dry or precipitate contaminated runways. Application of ESDU 05011 and ESDU 13007. Step-by-step solutions involving use of the model@ with detailed explanations@ are provided in ESDU 10003@ Worked example of tyre in linear motion on a dry or contaminated runway surface. Application of ESDU 05011.