Evaluation of Airborne Precision Spacing in a Human-in-the-Loop Experiment

Abstract

A significant bottleneck in the current air traffic system occurs at the runway. Expanding airports and adding new runways will help solve this problem; however, this comes with significant costs: financially, politically and environmentally. A complementary solution is to safely increase the capacity of current runways. This can be achieved by precisely spacing aircraft at the runway threshold, with a resulting reduction in the spacing buffer required under today's operations. At NASA's Langley Research Center, the Airspace Systems program has been investigating airborne technologies and procedures that will assist the flight crew in achieving precise spacing behind another aircraft. A new spacing clearance allows the pilot to follow speed cues from a new on-board guidance system called Airborne Merging and Spacing for Terminal Arrivals (AMSTAR). AMSTAR receives Automatic Dependent Surveillance-Broadcast (ADS-B) reports from an assigned, leading aircraft and calculates the appropriate speed for the ownship to fly to achieve the desired spacing interval, time-or distance-based, at the runway threshold. Since the goal is overall system capacity, the speed guidance algorithm is designed to provide system-wide benefits and stability to a string of arriving aircraft.An experiment was recently performed at the NASA Langley Air Traffic Operations Laboratory (ATOL) to test the flexibility of Airborne Precision Spacing operations under a variety of operational conditions. These included several types of merge and approach geometries along with the complementary merging and in-trail operations. Twelve airline pilots and four controllers participated in this simulation. Performance and questionnaire data were collected from a total of eighty-four individual arrivals. The pilots were able to achieve precise spacing with a mean error of 0.5 seconds and a standard deviation of 4.7 seconds. No statistically significant differences in spacing performance were found between in-trail and merging operations or among the three modeled airspaces. Questionnaire data showed general acceptance for both pilots and controllers. These results reinforce previous findings from full-mission simulation and flight evaluation of the in-trail operations. This paper reviews the results of this simulation in detail.

Evaluation of an Airborne Spacing Concept, On-board Spacing Tool, and Pilot Interface

“…Previous experiments have demonstrated that flight deck based spacing can deliver aircraft to the runway with mean errors less than seven seconds and standard deviations less than five seconds. 4,5,13,[23][24][25] In contrast, baseline scenarios of current day operations conducted at MITRE have produced a mean spacing error of 24.75 seconds and a standard deviation of 17.02 seconds. 4,5 The inter-arrival time recorded in this experiment revealed an interaction effect between Control Method and Error Source (p = 0.002), and results of post hoc comparisons revealed that scenarios conducted using RTA procedures during the presence of wind error resulted in a greater arrival error when compared with each of the other five Control Method by Error Source combinations (p < 0.05).…”

Operational Concept for Flight Crews to Participate in Merging and Spacing of Aircraft

“…15 This precise delivery of aircraft yields a 10 to 15 second reduction in the separation buffer and equates to at least a 10% increase in throughput for a nominal 120 second IFR separation criteria (5 nautical mile separation at 150 KIAS final approach speed approximates 120 seconds).…”

“…Past research indicates having the speed calculated on board the aircraft produces quicker and more accurate speed commands, and therefore allows flight crews to fly a speed that more precisely deliverers the aircraft to the runway at the desired time. 7,[15][16][17] Initial feedback from pilots during simulation studies indicate no significant change in workload is required to achieve the significant improvement in precision of aircraft delivery to the runway. Results from experiments conducted by MITRE and NASA indicate flight crews can consistently deliver aircraft to the runway within 5 seconds of the desired time, creating the potential to reduce the separation buffer added to minimum separation criteria, thereby increasing runway throughput.…”

Airborne Precision Spacing: A Trajectory-Based Aprroach to Improve Terminal Area Operations

“…A human-in-the-loop study conducted in NASA's Air Traffic Operations Laboratory (ATOL) tested the merging, as well as in-trail, operations [13]. The ATOL was used to study strings of 9 aircraft arriving to one of three modeled airspaces.…”

“…Subject questionnaires from the Integration Flight Deck (IFD) and ATOL studies show that pilots feel that the overall workload when spacing was not significantly different than the workload without spacing [9], [13]. Eye scan data collected during the IFD tests also show minimal change to the pilots scan pattern and dwell time when spacing compared to non-spacing [22].…”