No abstract

Convective weather can cause arrival traffic to fly less efficient weather avoidance routes and is the primary cause for time-based metering to be discontinued. Dynamic Arrival Routes (DAR) is a trajectory-based weather avoidance system that is designed to help improve arrival traffic flow when weather is present. The DAR system continuously analyzes airborne arrival flights for opportunities to reroute them to more efficient arrival routes or around weather that is predicted to be on their current flight plan early enough to allow the arrival time-based metering system to adjust its times of arrival for the presence of weather. Analysis of 93 hours of actual traffic over 12 different days from Fort Worth Center showed DAR proposed more efficient arrival reroutes for 352 arrival flights for an average time savings of 12.3 minutes per flight at a look-ahead time of 60 minutes from the meter fix. DAR also identified 642 arrival flights with a need to deviate around weather and proposed weather avoidance routes that were analytically shown to remain weather-free 83 percent of the time for a look-ahead time of 30 minutes from the meter fix.

No abstract

This paper presents analyses of the strategic airspace constraints and the environmental impact of Dynamic Weather Routes automation. The Dynamic Weather Routes are flight plans along which an aircraft can save a user-specified amount of windcorrected flying time compared to the currently active flight plan. The strategic airspace constraints address sector congestion and Special Activity Area traversal along the two flight plans. The environmental impact considers fuel burn and emissions (e.g., hydrocarbons, carbon dioxide, etc.) along the two flight plans. A comparison of airspace constraints and emission values between the as-flown tracks of the aircraft and the suggested Dynamic Weather Route is presented. The results are for August 1 through October 31, 2012, when NASA's Dynamic Weather Routes software was running continuously at the American Airlines System Operations Center in Ft. Worth, TX. The results indicate that Dynamic Weather Routes not only save flying time and fuel, but help reduce traffic congestion and harmful emissions as well.

Under current National Airspace System operations conflict alerts for aircraft in holding patterns are often missed or in error due to the fact that trajectories for holding aircraft are not modeled in existing Conflict Alert or Conflict Probe automation. In addition, a controller in one sector may not know when aircraft are holding in a neighboring sector. These factors can lead to an increased potential for loss of separation while aircraft are flying in holding patterns. The objective of this work is to develop a holding function that automatically determines when an aircraft enters a holding pattern, computes a holding region around the pattern, and probes the holding region for conflict with other traffic. Since controller workload is generally high during periods when aircraft are in holding the operational concept of use assumes the holding region is automatically computed and the controller is alerted only if another aircraft is predicted to fly through the holding region. The holding algorithm is applied only to aircraft that would likely go into holding during rush periods, e.g., arrivals to capacity constrained airports. A holding region is computed for aircraft that settle out on a steady outbound course. Initial estimates of the holding fix position, turn radius, and holding pattern leg length are computed and automatically updated as the aircraft flies the pattern. The holding algorithm was implemented in the Center/TRACON Automation System software suite and tested using Host radar track and flight plan data from the Fort Worth Air Route Traffic Control Center. Of 37 aircraft that went into holding during a 1 hour severe weather period, the holding function correctly computed and updated 34 holding regions that accurately reflected the holding pattern airspace. One of these aircraft was involved in an operational error that would certainly have been prevented had the 3 min holding alert been displayed to the controller. In 3 cases the holding region was activated incorrectly, then deactivated following subsequent track updates, and later computed correctly on the second outbound leg. The results show that Host track and flight plan data alone may be used to automatically model and conflict probe holding airspace in real-time.