Predictability of Top of Descent Location for Operational Idle-Thrust Descents

To enable arriving aircraft to fly optimized descents computed by the flight management system (FMS) in congested airspace, ground automation must accurately predict descent trajectories. To support development of the trajectory predictor and its uncertainty models, commercial flights executed idle-thrust descents at a specified descent speed, and the recorded data included the specified descent speed profile, aircraft weight, and the winds entered into the FMS as well as the radar data. The FMS computed the intended descent path assuming idle thrust after top of descent (TOD), and the controllers and pilots then endeavored to allow the FMS to fly the descent to the meter fix with minimal human intervention. The horizontal flight path, cruise and meter fix altitudes, and actual TOD location were extracted from the radar data. Using approximately 70 descents each in Boeing 757 and Airbus 319/320 aircraft, multiple regression estimated TOD location as a linear function of the available predictive factors. The cruise and meter fix altitudes, descent speed, and wind clearly improve goodness of fit. The aircraft weight improves fit for the Airbus descents but not for the B757. Except for a few statistical outliers, the residuals have absolute value less than 5 nmi. Thus, these predictive factors adequately explain the TOD location, which indicates the data do not include excessive noise.

• Record URL:
  http://www.aviationsystemsdivision.arc.nasa.gov/publications/2010/Stell_ATIO2010_final.pdf
• 
• Supplemental Notes:
  • Presented at 10th American Institute of Aeronautics and Astronautics Aviation Technology, Integration, and Operations Conference, Fort Worth, Texas, September 13-15, 2010.
• Corporate Authors:

  National Aeronautics and Space Administration

  Ames Research Center
  Moffett Field, CA  United States  94035
• Authors:
  • Stell, Laurel L
• Publication Date: 2010-9

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 12p

Subject/Index Terms

• TRT Terms: Air traffic control; Descent; Flight paths; Goodness of fit; Multiple regression analysis; Pilotage; Uncertainty
• Uncontrolled Terms: Flight management system; Flight trajectories
• Subject Areas: Aviation; Operations and Traffic Management;

Filing Info

• Accession Number: 01358983
• Record Type: Publication
• Report/Paper Numbers: ARC-E-DAA-TN2171
• Files: TRIS
• Created Date: Dec 16 2011 2:47PM