In order to provide increased utilization of the airspace, separation standards may decrease between runways, between aircraft, between landing operations, and for vertical separation.
For mixed operations such as conventional departures and RNAV Off-the-Ground, current separation standards may need to be modified.
Current separation standards are based on independent (>4300 ft. runway separation) or dependent (2500>runway separation>4300 ft.) approach flows.
The hope is that RNP approaches will be so accurate that separation standards can be safety reduced. Radius-to-Fixed turn legs must be flown by the automation.
- Uncertain availability of technologies and procedures enabling reduced separation especially space-based navigation/timing assets.
- Uncoordinated ground flow control and departure/approach flows due to separation of functions.
- NextGen/SESAR hazard condition: As departing aircraft taxi to runway, ground controller overly relies on observing automation to monitor conformance. Associated human performance hazard: Ground Controller fails to issue corrective instruction to resolve conflict because of lack of alert from surface automation. Ground controller is overly reliant on conformance alert. ASDE-X (based on transponder codes) is not currently used for ground separation purposes.
- NextGen/SESAR hazard condition: Departing aircraft deviates from issued taxi route. Surface automation provides conformance alerts and is overly sensitive with a high rate of nuisance alerts. Associated human performance hazard: Ground Controller ignores accurate conformance alert and fails to issue corrective instructions for a true alert.
- NextGen/SESAR hazard condition: Arriving aircraft deviates from control instructions. Controller performs conformance monitoring with assistance from automation. Automation is overly sensitive with a high rate of nuisance alerts. Associated human performance hazard: Controller ignores accurate conformance alert and fails to issue corrective instructions for a true alert.
- NextGen/SESAR hazard condition: Automation identifies candidates for delegated spacing. Associated human performance hazard: Automation indentifies incorrect candidate.
- NextGen/SESAR hazard condition: Automation used to sequence aircraft. Associated human performance hazard: Controller fails to notice flaw in automation sequence.
- NextGen/SESAR hazard condition: Pilots establish linkage with paired aircraft. Associated human performance hazard: Pilot fails to establish linkage. Pilot establishes linkage with incorrect aircraft.
- Failure or lack of available backup systems
- Failure of systems in in-trail aircraft to detect and warn of high-strength wake vortices
- Inaccurate modeling of wake location and strength
Corroborating sources and comments
A REDUCED AIRCRAFT SEPARATION RISK ASSESSMENT MODEL
Roger Shepherd, Rick Cassell, Rajeev Thapa, Derrick Lee
Rannoch Corporation, 1800 Diagonal Road, Suite 430, Alexandria, VA 22314
Sawyer, Michael, Ph.D., Berry, Katie, Ph.D., Blanding, Ryan, NextGen Human Hazard Assessment Report, TASC, Inc., Washington, DC, November 2010
Reduced Horizontal Separation Minima (RHSM) Concept Exploration Simulation
Elizabeth Elkan, ACT-540 Parimal Kopardekar, Ph.D., SRC David Stahl, SRC
IFATCA Vision Document (Towards the 21st Century)
European Study on Reduced Separation Minima –RESET (2009)