AoC number


Primary domain



  1. It is the interaction of aircraft of vastly different size, speed and complexity in procedural airspace will necessitate close attention in the shorter term.
  2. In the longer-term future (2025-2050), the airspace may contain and even be dominated by a much more heterogeneous mix of vehicles than exist today. These fleets will include conventionally piloted, remotely piloted, and fully autonomous vehicles that have large variations in speed, altitude, mass, and operating characteristics.
  3. Not all aircraft will have the same level of equipage in the future. The promise of advanced air traffic management concepts such as SESAR and NextGen relies on a critical mass of aircraft equipped with the similar technologies. ( NOTE: Or a large group of airlines that successfully begins flying 4-D trajectories because, a. they have capable aircraft, and b. they are willing to invest in a computer system to generate the 4-D trajectories.) SESAR/NextGen capabilities will not be used in certain areas of the world. There will be regions of the world that cannot afford to equip their aircraft to SESAR/NextGen standards. The variation in sophistication of digital and electromechanical systems within an individual aircraft type must also be considered. Unless fundamental changes are made in aircraft lifespan assumptions, there will continue to be unavoidable mixes of new and reused (legacy) software. There will be a significant number of aircraft equipped with more advanced avionics than the majority of the legacy fleet.

Potential hazard

  1. ATC coordination problems when low-technology aircraft are mixed with high technology aircraft in high-technology airspace and associated.
  2. Loss of separation of mixed technology aircraft sharing same airspace.
  3. NextGen/SESAR hazard condition: Several issues arise in a controller’s sector, many involving mixed equipage. Controller reviews the events and prioritizes response to them. Associated human performance hazard: Controller misprioritizes response order of events.
  4. NextGen/SESAR hazard condition: TMC Reroute is de-conflicted by automation probe. Sector controller resolves any remaining predicted problems with the reroutes as necessary. Associated human performance hazards: Sector controller overly reliant on automation and TMU to resolve sector issues. Controller fails to identify/resolve predicted problems in a timely manner.
  5. Departure separation issues for between aircraft equipped for “RNAV-off-the-ground” departures and those unequipped..
  6. Airports open only to equipped aircraft
  7. Near mid-air collisions in complex Metroplex environments.

While future technologies will provide new and innovative solutions and efficiencies, it will be essential to continually monitor triggers for airspace change, review procedures and assess surveillance strategies.

Corroborating sources and comments

  • Airspace Phase Transitions and the Traffic Physics of Interacting 4D Trajectories; Bruce K. Sawhill, James W. Herriot
  • Sawyer, Michael, Ph.D., Berry, Katie, Ph.D., Blanding, Ryan, NextGen Human Hazard Assessment Report, TASC, Inc., Washington, DC, November 2010
  • Bruce J. Holmes, and Ken Seehart, NextGen AeroSciences, LLC, Williamsburg, VA, Ninth USA/Europe Air Traffic Management Research and Development Seminar (ATM2011)
  • February 21, 2013: Airbus Predicts Move To Larger Planes: Says Airlines Want To Lower The Cost-Per-Seat On Existing Routes. An Airbus executive says that the company thinks airlines will begin looking at larger aircraft as they seek to lower their cost-per-seat on existing routes. Airbus’ director for strategic marketing and analysis Andrew Gordon said in an interview in Helsinki that there has been an “upscaling” in the airplanes that are being sold. He told Bloomberg News that the changes are being “driven by existing routes getting bigger as well as airlines lowering their seat costs.” He said the trend is factored into the planemaker’s sales forecasts.

Last update

February 21, 2013