In June 2014, the Federal Aviation Administration implemented new rules at Hartsfield-Jackson Atlanta International Airport for keeping airplanes far enough apart so they are not affected by each other’s wake turbulence. It is the fourth airport in the last 18 months to implement such wake turbulence recategorization, or RECAT. This work is part of the agency’s continuous efforts to improve efficiency and reduce the aviation industry’s environmental impact and aligns well with ASPIRE’s best practices in the areas of arrivals optimisation and departure optimisation.
Memphis International Airport was the first airport to implement RECAT in November 2012, and Louisville International Airport followed in September 2013. Cincinnati/Northern Kentucky International Airport adopted the revised NextGen separation standards this past March.
Wake RECAT more narrowly and accurately defines safe wake turbulence separation standards based on the performance characteristics of aircraft. This eliminates conservatively long separation standards that are necessary under current broader wake-turbulence classifications, which are based primarily on aircraft weight classes. The standards were last updated in 1994, when the FAA defined five classes of aircraft -- heavy, B757, large, small-plus and small. After the wake turbulence separation for the A380 was determined in 2008, the super class was added.
The new system also has six categories, identified by the letters A through F, but reflecting recent research into wake physics, they are based on aircraft weight, approach speeds, wing characteristics and other special considerations. Depending on the pairings of leading and trailing aircraft, RECAT requires less or more separation than before or the same amount.
Once controllers learn the standards, they can use different tools to decrease the separation of arriving aircraft while also enhancing safety, reducing delays, saving fuel and reducing aviation’s environmental impact.
One tool, simply adding the wake category into the data block, shows controllers the wake categories for leading and trailing aircraft as they approach a runway. Separation distance categories were also added to flight strips.
Another tool, the automated terminal proximity alert, gives controllers a readout of the required separation between two aircraft. ATPA also digitally indicates the separations achieved and monitors the speed of planes to show if they are losing separation.
The NextGen-funded Wake Turbulence Research Program has been analyzing operational data collected from each airport before and after RECAT implementation to compare and contrast the operational advantages of the new wake separation standards.
Analyses have shown about a 20 percent capacity gain for arrivals and departures at Memphis during instrument meteorological conditions. Before RECAT, Memphis accepted 77 per hour. Now the airport has raised that rate to 99 per hour. FedEx, which is headquartered in Memphis, reported $1.8 million in savings per month as a result of the changes.
Louisville is experiencing similar capacity gains. UPS is headquartered there and is saving 52,000 pounds of fuel per night on its arrivals.
The FAA and its controllers union have been able to explain RECAT to controllers and pilots so they can understand how it works and see that safety is not sacrificed when aircraft separation is decreased under specific parameters.
Safety example for wake turbulence separations
This collaborative effort is improving the efficiency of the NAS, and the results are being noticed almost immediately after the new procedures are implemented at a facility.
The FAA is working to identify other opportunities and locations for implementing wake RECAT over the next three years.
Honolulu International Airport is tentatively scheduled to implement RECAT in 2015, which would bring these additional efficiencies and emissions savings to the Asia Pacific region. The Northern California Terminal Radar Approach Control facility is also in the discussion about future implementations, which would benefit several current and future ASPIRE-Daily city pairs.