Airspace risk management using surveillance track data: Stabilized approaches

The outcome of operations in a designated airspace is a function of the cooperation between flights in the airspace and the coordination of Air Traffic Control (ATC). A critical airspace is the approach airspace in which flights are sequenced and separated to minima to maximize utilization of the available runways. Airline procedures call for flights to meet “stable approach criteria” at 1000 ft. and 500 ft. above ground level (AGL). ATC procedures define the trajectories flown, including airspeed, to maximize throughput through the airspace and runways. The ability to achieve the stabilized approach criteria is therefore a function of the coordination of the flight crews and ATC. This paper describes a method for analysis of stabilized approaches using surveillance track data. Risk events and factors related to stabilized approach criteria are defined. A case study of 8,219 approaches is conducted at a runway of slot controlled airport with a dominant carrier. The results quantify the portion of the approaches which violate the stabilized approach criteria. Results show that 27.8% of the approaches exhibited more than 10 knots change in groundspeed after sequencing 1000 ft. AGL, 14.1% after sequencing 750 ft. AGL, and 4.4% after sequencing 500 ft. AGL. The flights with rate of descent in excess of 1000 feet per minute (fpm.) are also studied. The effects of factors such as the speed at Final Approach Fix (FAF) and the runway centerline/glidepath acquisition position are analyzed. Results show that a flight that acquires glidepath after FAF has a higher probability of having an excessive speed change from 1000 ft. AGL to the runway threshold. Aircraft weight classes are also studied. The results indicate a lower landing speed and higher deceleration rate for small aircraft. The implications of these results and the limitations of using surveillance track data for this purpose are discussed.