A Risk Observatory for the total aviation system is being developed in the scope of project 4 of the Future Sky Safety program. The goal of the risk observatory is to collect data from all involved domains in order to compute and monitor the operational risks as well as to derive risk mitigation or reduction measures to improve the safety level throughout the system. The focus of this present work is the Physical Model, which contributes to the buildup of the Risk Observatory. The Physical Models use the relationships of contributing and influencing factors with respect to the aircraft’s flight dynamics in order to simulate the flight operations from the operator’s point of view. The goal of the approach is to quantify the occurrence probability of runway excursions in order to use this as a safety performance indicator. Connections to other models used by other domains are shown as well as the contribution of the Physical Models to the Risk Observatory.