The capability enables the drones to take account of failure modes, such as command and control (C2) link failure, and take measures to ensure the safety of the vehicle, other vehicles and people and property on the ground. This includes identification of possible problems (auto-diagnostic) and all equipment required to manage solutions.
The reference for this definition is the "European ATM Master Plan: Roadmap for the safe integration of drones into all classes of airspace". On-going Research activities on U-space may update this definition in future datasets. Note that in this reference this capability is identified as U1/U2.