2021 AIAA Aviation Forum: Accommodating operational uncertainty in UAM with strategic deconfliction

As many of our readers are well aware, The American Institute of Aeronautics and Astronautics (AIAA) is a worldwide leader in the global aerospace industry as the largest technical society devoted to the global aerospace profession. This year, I was honored to present our Airbus UTM paper titled “Accommodating Operational Uncertainty in Urban Air Mobility Operations with Strategic Deconfliction” at their annual Aviation Forum event.

In the next two decades, the aviation industry will experience significant growth, including in the urban environment from Unmanned Aircraft Systems (UAS) for package delivery operations and vertical takeoff and landing (VTOL) cargo and passenger air taxis. Existing air traffic management (ATM) procedures are not expected to scale sufficiently to support this growth, and hence approaches from UAS Traffic Management (UTM) are being explored for Urban Air Mobility (UAM). One such approach is the use of strategic deconfliction – resolving a predicted conflict prior to departure or well upstream of it – to support separation provision.

Our paper explores the effectiveness of strategic deconfliction in mitigating the impact of operational uncertainty on scheduled and unscheduled flight delays for Urban Air Mobility (UAM) operations. We simulated three different approaches to strategic deconfliction which varied how operations were rescheduled when they incurred departure or airborne error. These simulations were compared to a baseline that simulated tactical deconfliction without strategic deconfliction.

The three approaches simulated were:

  1. Strategic deconfliction with a tight conformance requirement: conforms to the minimum spacing requirement.
  2. Strategic deconfliction with a relaxed conformance requirement: similar to that used for internal departure scheduling in Time-Based Flow Management.
  3. Strategic deconfliction with no conformance requirement: operations were never rescheduled into the existing schedule, only replanned tactically.

A range of demand levels representing early-stage UAM operations were simulated using a conceptual network of vertiports located near three major airports—SFO, SJC and OAK—in the San Francisco Bay Area.

The work resulted in four key findings:

  1. UAM departure and airborne delays under strategic deconfliction are highly sensitive to how much rescheduling is required into the existing schedule.
  2. Results simulating the baseline with no strategic deconfliction show low delays suggesting tactical deconfliction alone could be effective at managing operational uncertainty in UAM operations. This analysis did not, however, incorporate safety metrics which we plan to explore in future work.
  3. Strategic deconfliction with a tight conformance requirement may not be a feasible approach to managing operational uncertainty due to the high resulting delays, passenger sensitivity to travel time and potential energy limitations of future UAM vehicles.
  4. Relaxing the slot conformance requirement shows improved results. While the relaxed conformance requirement simulated may only be feasible at low demand or uncertainty levels, results simulating no conformance requirement show significantly reduced delays even at high demand and uncertainty levels.

Our research unveils key findings about how to manage UAM operations with and without strategic deconfliction. Our ongoing research will explore the safety implications of the approaches we have presented, as well as research the use of demand capacity balancing to strategically manage traffic instead of using strategic deconfliction. Stay tuned for more updates!

To read the full paper, please visit HERE.

- Tony Evans