The Spot and Runway Departure Advisor, or SARDA, is NASA’s contribution to improving the efficiency of airport surface operations. It is the centerpiece of a partnership among airlines, airports, and air traffic controllers to improve operations at the nation’s busiest airports.
There are two main sources of inefficiencies in current airport surface operations. One is peak traffic due to multiple aircraft that push back from their gates at around the same time causing long runway queues and congestion on taxiways. Stop-and-go taxi operations resulting from surface congestion can potentially delay takeoff times and limit airport throughput.
The second source of airport surface inefficiencies results when relevant planning information is not shared between various airport surface stakeholders such as controllers in the ramp and air traffic control towers (ATCT). Thus, decisions made by each entity may not be the most efficient and sometimes may even be counterproductive to overall operations.
SARDA uses time-based metering of aircraft to reduce the congestion on the airport surface, and facilitates a collaboration amongst the various airport surface stakeholders for obtaining better situational awareness of flight operations information. Then, for each aircraft, SARDA provides metering advisories at three main locations: gate, spot, and runway. By controlling the release of aircraft from the gates and the spots, SARDA effectively shifts the delays from the taxiways and runways to the gates. By incurring delays at the gates, with aircraft engines off, fuel and emissions are reduced. Metering of aircraft at the gates also reduces the number of aircraft on the movement area at any time, increasing predictability.
The SARDA concept has been evaluated in human-in-the-loop (HITL) simulations at NASA Ames Research Center’s FutureFlight Central (FFC) facility. Aircraft traffic was simulated on the surface and in the airspace near the airport, and displayed on radar maps. Metering advisories from the optimization algorithm were either shown to ATCT controllers through an Electronic Flight Strip (EFS) display system or to ramp controllers through NASA’s Ramp Traffic Console (RTC).
Three sets of HITL simulations have been successfully conducted, modeling SARDA in operation at Dallas/Fort Worth International Airport (DFW) in 2010 and 2012, and at Charlotte/ Douglas International Airport (CLT) in 2014. In the 2012 simulation of surface operations on the east side of DFW, researchers observed SARDA could achieve reductions of up to 60% in taxi delays and estimated 33% in fuel and emissions. In the CLT simulations, SARDA advisories were found to reduce the departure taxi delay by one minute per flight and the fuel consumption of departing flights by 10-12%. Wait times in the departure runway queue were also found to be reduced, which suggests SARDA improved takeoff time conformance and lowered tower controller workload.
Looking ahead, plans are underway to conduct a joint field test with American Airlines in 2016. Prototype SARDA ramp decision support automation will be tested with operations at CLT.