  In this paper, we analyze the numerical stability of the popular Longley-Rice
Irregular Terrain Model (ITM). This model is widely used to plan wireless
networks and in simulation-validated research and hence its stability is of
fundamental importance to the correctness of a large amount of work. We take a
systematic approach by first porting the reference ITM implementation to a
multiprecision framework and then generating loss predictions along many random
paths using real terrain data. We find that the ITM is not unstable for common
numerical precisions and practical prediction scenarios.
