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Advanced Surveillance Enhanced Procedural Separation

What it does

Improved oceanic surveillance could be the next opportunity for ADS-B coverage for the FAA. As part of a project called Advanced Surveillance Enhanced Procedural Separation (ASEPS), the FAA is analyzing two methods of improving surveillance coverage in oceanic service volumes: Space-Based ADS-B reports and more frequent Automatic Dependent Surveillance – Contract (ADS-C) reports.

Space-Based ADS-B may be the next step in the ADS-B evolution: moving from the current system of ADS-B ground stations to radios hosted on satellites, enabling surveillance across the entire globe.

With the Space-Based ADS-B concept, aircraft may be tracked anywhere they fly in near real-time, increasing safety and efficiency for all users. No additional avionics beyond current mandates for 2020 would be required, and only minimal changes to the existing ADS-B ground infrastructure would be necessary.


  • Potential for reduced separation standards in oceanic airspace
  • Improved accommodation of altitude, speed and route change requests
  • Precise approach in non-radar airspace (specifically at small South Pacific islands)
  • Precision surveillance over oceanic airspace
  • Accurate and timely information for search and rescue operations
  • Harmonization across international airspace boundaries
  • Improved controller situational awareness
  • Conflict detection and resolution

How it works

The ground system would receive high update rate Space-Based ADS-B or ADS-C surveillance reports, which could support reduced separation standards in oceanic airspace. This surveillance could be displayed on the ground system, which may be used for improved situational awareness for controllers who manage traffic procedurally in oceanic airspace.


The FAA currently is evaluating Space-Based ADS-B surveillance services for oceanic airspace. Testing will support development of the safety case, pre-operational assessments, and end-to-end system performance of Space-Based ADS-B in FAA automation systems.

The FAA plans to make a decision in 2018 whether to invest in Space-Based ADS-B. If so, Space-Based ADS-B could be enabled on ATOP (Advanced Technologies and Oceanic Procedures) in 2020.

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