Abstract: One of the most fundamental changes to the traffic management system is the use of trajectory based operations (TBO)(SESAR, 2007; FAA, 2014). TBO generates a shift from manual, tactical air traffic control, to more automated, strategic traffic management. With the introduction of such fundamental change to the ATM system, system safety and resilience (e.g. Hollnagel, 2010) is a critical concern. An important element of maintaining safety and resilience in air traffic is the ability of systems…