Analysis Blunder Risk Model is a computational model to evaluate the probability of a collision, given a particular blunder (controller error, pilot error, equipment malfunction) between one aircraft involved in the error (the “blunderer”) and another aircraft (the “evader”). ABRM considers both the probability of a collision assuming no intervention, and then the probability of timely intervention by pilots or controllers. It uses empirical probability distributions for reaction times and a closed form probability equation to compute the probability that a collision will occur. This permits it to consider combinations of events with small probabilities efficiently and accurately.
ABRM is programmed in Excel (with macros). Developed by Ken Geisinger (FAA) in 1985.