In-Flight Contingency Management for Unmanned Aerial Vehicles

Contingency analysis and reaction is a critical task to be carried out by any airplane to guarantee its safe operation in a non-segregated airspace. Pilot’s reactions to any kind of incidences that may occur in-flight, like engine malfunctions, loss of electrical power, hydraulic failure, unexpected weather, etc, will determine the fate of the flight. Nowadays, contingency reactions are mainly driven by the airplane manufacturer, with pre-analyzed contingency scenarios covered in the airplane documentation, and by ICAO’s rules as defined in the way flight plans should be prepared and landing alternatives implemented. Flight dispatching is the set of tasks related to flight preparation, such as load and balance, meteorology study and briefing, operational flight planning, contingency analysis and planning, etc. However, managing contingencies on a UAS is a much more complex problem basically due to the automated nature of the vehicle and the lack of situational awareness that pilot’s in command should face. It is well known from the short history of UAS accidents that many of them are directly imputable to pilot errors when trying to manage an unexpected contingency. In this paper we will introduce an structured approach to automate contingency reactions in UAS. Our objective is to classify the contingency sources and up to a certain level abstract their impact on the system operation. Contingencies can be related to four wide aspects of the UAS operation: the flight itself, the mission, the payload, and the awareness systems. depending on the level of severity the contingency reaction may involve changing or canceling mission objectives to canceling the flight itself. In this way, the response to the contingency can be selected from a predefined limited catalog of automated reactions that may reconfigure the UAS operation in all aspects. This structured approximation is only possible because the contingency management is built upon a highly capable architecture called USAL (UAS Service Abstraction Layer) that offers capabilities to properly monitor contingencies and the flexibility to command pre-planned contingency reactions that may affect the flight operation and/or the mission carried out by the system. Contingency management becomes directly dependent upon the UAS dispatching process. USAL provides a dispatching methodology that identified the mission objectives, the UAV airframe and its various characteristics, the software services required for managing the flight and the mission, the sensor and computational payload, etc. All these elements are combined together in an iterative dispatching flow. The result of the process is the actual UAS configuration in terms of fuel, electrical system, payload configuration, flight plan, etc; but also detailed flight plan, alternative routes and landing sites, detailed USAL service architecture and the required contingency planning.