ABSTRACT
Having reliable methods for identifying slippery runway conditions is very important. However, measuring the runway frictionwith a satisfactory precision is very difficult. There are two main reasons for these problems. Firstly, measuring the runway friction with a satisfactory precision is very difficult. While many different measurement devices have been developed, it is hard to find equipment that produces stable and consistent results. The second problem is that in order to measure friction, the runway needs to be shut down. Thus, in order to avoid severe delays to the traffic, such measurements cannot be carried out too frequently. As a result the braking action reports are often too old to be useful. This is especially true during heavy snowfalls, where the conditions change very rapidly.
