400328_M_1Y.ppt Thompson MIT Lincoln Laboratory Analysis of Terminal Separation Standards and Radar Performance Dr. Steven D. Thompson Dr. Steven R. Bussolari 26 June 2003 ATM 2003 Budapest Hungary *This work is sponsored by the Federal Aviation Administration under Air Force Contract #F C Opinions, interpretations, conclusions, and recommendations are those of the author and are not necessarily endorsed by the U.S. Government.

400328_M_2Y.ppt Thompson MIT Lincoln Laboratory Outline Motivation Problem Statement and Approach Surveillance Analysis Findings Summary

400328_M_3Y.ppt Thompson MIT Lincoln Laboratory Motivation Airspace "Terminalization" A primary goal of the FAA’s Operational Evolution Plan is the expanded use of 3-mile separation and terminal procedures Operational benefit includes more efficient control of aircraft during transition to and from airports FAA Operational Evolution Plan hhtp://www2.faa.gov/programs/oep/

400328_M_4Y.ppt Thompson MIT Lincoln Laboratory Motivation Consolidated Terminal Radar Control (TRACON) Being commissioned –Southern California TRACON –Northern California TRACON –Potomac TRACON Need 3-mile separation throughout the extended airspace to achieve operational benefits BWI IAD DCA ADW Chesapeake Bay IAD BW1 ADW DCA

400328_M_5Y.ppt Thompson MIT Lincoln Laboratory Outline Motivation Surveillance Analysis Findings Next Steps Problem Statement and Approach –Current Radar Separation Standards –Radar Surveillance Environments –Analysis Approach Summary

400328_M_6Y.ppt Thompson MIT Lincoln Laboratory Current Radar Separation Standards Separation standards are contained in FAA Order N The order requires 5-mile separation if either aircraft is 40 miles or more from the same sensor antenna The order allows 3-mile separation when both aircraft are less than 40 miles from and tracked by the same sensor antenna A separation of 3 miles is not permitted with a mosaic display; 5-mile separation is required Allowable separation depends on range from sensor antenna

400328_M_7Y.ppt Thompson MIT Lincoln Laboratory Radar Surveillance Environments Single-Site In single-site environment both aircraft must be within 40 nmi of the sensor to allow 3 nmi separation Air Traffic Control Sectors 3 nmi 5 nmi 60 nmi 40 nmi

400328_M_8Y.ppt Thompson MIT Lincoln Laboratory Radar Surveillance Environments Mosaic In mosaic environment each geographic area (radar sort box) is assigned a: –Preferred sensor –Supplemental sensor –Tertiary sensors Currently 3 mile separation is not permitted in mosaic environment Radar Sort Box

400328_M_9Y.ppt Thompson MIT Lincoln Laboratory Analysis Approach Analyze the error characteristics of beacon sensors in the FAA inventory Analyze additional errors introduced with mosaic environment Perform statistical modeling of surveillance errors to: –Derive surveillance requirements based on currently acceptable performance of existing sensors –Determine acceptable coverage area of newer more accurate sensor systems, in both single sensor and mosaic environments, that meet currently acceptable performance standards

400328_M_10Y.ppt Thompson MIT Lincoln Laboratory Outline Motivation Surveillance Analysis –Error Characteristics of FAA Sensors –Additional Errors Introduced by Mosaic Display –Statistical Model of Surveillance Errors Findings Next Steps Problem Statement and Approach Summary

400328_M_11Y.ppt Thompson MIT Lincoln Laboratory Error Characteristics of FAA Beacon Sensors Secondary Surveillance Range Errors Range measurement errors are primarily due to errors in measuring the round trip travel time and errors in transponder turnaround time Range errors are small (  200–400 feet) and do not vary with range Transponder Antenna

400328_M_12Y.ppt Thompson MIT Lincoln Laboratory Error Characteristics of FAA Beacon Sensors Secondary Surveillance Azimuth Measurement Techniques Older “sliding window” –Measures azimuth as the center of multiple replies –Typical accuracy  4 milliradians –Examples: BI-4, BI-5 Newer Monopulse Secondary Surveillance Radar (MSSR) –Makes azimuth measurements for each reply –Typical accuracy  1.2 milliradians –Examples: Mode S, BI-6 MSSR offers a 3-fold improvement in azimuth accuracy

400328_M_13Y.ppt Thompson MIT Lincoln Laboratory Outline Motivation Surveillance Analysis –Error Characteristics of FAA Sensors –Additional Errors Introduced by Mosaic Display –Statistical Model of Surveillance Errors Findings Next Steps Problem Statement and Approach Summary

400328_M_14Y.ppt Thompson MIT Lincoln Laboratory Spatial Errors in Displayed Separation Single Sensor vs Mosaic Display Actual Separation Single Sensor Displayed Separation Bias Error (correlated) Multiple Sensors Mosaic Display Actual Separation Displayed Separation Bias Error Radar 1 Bias Error Radar 2 Bias errors are only reflected in separation measurements in mosaic display. Radar Sort Box Boundary

400328_M_15Y.ppt Thompson MIT Lincoln Laboratory Actual Separation Displayed Separation Actual Separation Displayed Separation Temporal Errors in Displayed Separation Single Sensor vs Mosaic Display Movement Of Aircraft Between Updates Time differences between target updates are typically larger for mosaic display. Single Sensor Multiple Sensors Mosaic Display Radar Sort Box Boundary

400328_M_16Y.ppt Thompson MIT Lincoln Laboratory Outline Motivation Surveillance Analysis –Error Characteristics of FAA Sensors –Additional Errors Introduced by Mosaic Display –Statistical Model of Surveillance Errors Findings Next Steps Problem Statement and Approach Summary

400328_M_17Y.ppt Thompson MIT Lincoln Laboratory Monte Carlo Simulations to Estimate Errors in Measured Separation Modeled Error Sources Registration errors –Location bias –Azimuth bias Range errors –Radar bias –Radar jitter Azimuth errors –Azimuth jitter Transponder errors Aircraft movement between updates Data-dissemination quantization (common digitizer format) Mosaic Random Orientation Single Sensor Range to Midpoint  3 nmi  Range to Midpoint Range To Midpoint Radar Sort Box Boundary

400328_M_18Y.ppt Thompson MIT Lincoln Laboratory Monte Carlo Simulations to Estimate Errors in Measured Separation (Cont’d) Surveillance errors simulated in Monte Carlo simulations Statistics generated on errors in the separation displayed to a controller Position error distributions From model Measured Separation Actual Separation Probability density of measured separation  Standard deviation in measured separation Actual Separation Individual position estimate (sample) for each trial 1,000,000 trials

400328_M_19Y.ppt Thompson MIT Lincoln Laboratory Simulation Results for Sliding Window Short-Range Radar at a Range of 40 Nautical Miles Estimated Separation (nmi) Nautical Miles Probability Density Nautical Miles.06 33 33 Aircraft 2, Position ErrorsAircraft 1, Position Errors

400328_M_20Y.ppt Thompson MIT Lincoln Laboratory Measured Separation Probability Surface Sliding Window Short Range Radar Sliding Window Separation (nmi) Range from Sensor (nmi) Probability Density 33 33

400328_M_21Y.ppt Thompson MIT Lincoln Laboratory Range to Center of Two Aircraft Separated by Three Miles (nmi) Single Sensor Sliding Window  Displayed Separation Error (nmi) Current Acceptable Performance Results Measured Separation Errors for Short Range Radars Acceptable performance is defined by single sensor sliding window

400328_M_22Y.ppt Thompson MIT Lincoln Laboratory Results Measured Separation Errors for Short Range Radars MSSR short-range sensors provide currently acceptable single-sensor separation performance at ranges beyond 100 miles Range to Center of Two Aircraft Separated by Three Miles (nmi) Single Sensor MSSR  Displayed Separation Error (nmi) Current Acceptable Performance Single Sensor Sliding Window

400328_M_23Y.ppt Thompson MIT Lincoln Laboratory Results Measured Separation Errors for Short Range Radars MSSR short-range sensors provide currently acceptable single-sensor separation performance at ranges beyond 100 miles MSSR mosaic display of short-range sensors provides better than currently acceptable performance at 40 miles (i.e., each aircraft is within 40 miles of its respective sensor) Range to Center of Two Aircraft Separated by Three Miles (nmi) Mosaic MSSR Single Sensor MSSR  Displayed Separation Error (nmi) Current Acceptable Performance Single Sensor Sliding Window

400328_M_24Y.ppt Thompson MIT Lincoln Laboratory Results Measured Separation Errors for Short Range Radars MSSR short-range sensors provide currently acceptable single-sensor separation performance at ranges beyond 100 miles MSSR mosaic display of short-range sensors provides better than currently acceptable performance at 40 miles (i.e., each aircraft is within 40 miles of its respective sensor) Sliding window short-range sensors in mosaic display mode offer acceptable separation performance when each aircraft is within 28 miles of its respective sensor Range to Center of Two Aircraft Separated by Three Miles (nmi) Mosaic Sliding Window Mosaic MSSR Single Sensor Sliding Window Single Sensor MSSR  Displayed Separation Error (nmi) Current Acceptable Performance

400328_M_25Y.ppt Thompson MIT Lincoln Laboratory Results Measured Separation Errors for Long Range Radars MSSR long-range sensors provide currently acceptable single-sensor separation performance at ranges beyond 100 miles Sliding window and MSSR long-range sensors do not support 3-mile separation with mosaic display at any range Mosaic MSSR Single Sensor Sliding Window Single Sensor MSSR Range to Center of Two Aircraft Separated by Three Miles (nmi) 3  Displayed Separation Error (nmi) Current Acceptable Performance Mosaic Sliding Window

400328_M_26Y.ppt Thompson MIT Lincoln Laboratory Findings MSSR sensors (short- and long-range) offer acceptable separation performance for 3-mile separation at ranges beyond 100 miles for a single sensor MSSR short-range sensors in mosaic mode offer acceptable separation performance when each aircraft is within 40 miles of its respective sensor Long-range sensor update periods (12 seconds) are insufficient to support 3-mile separation with mosaic display

400328_M_27Y.ppt Thompson MIT Lincoln Laboratory Summary A technique has been developed to derive surveillance requirements for 3-mile separations –Using existing standards and sensors as a baseline Analysis shows significant expansion of 3-mile separation is possible –Using existing sensors and display techniques Further expansion may be possible –Using surveillance fusion to eliminate time bias errors