NASE DTW false target report

1. NASE DTW false target report To investigate the source of false targets on Runway 4R/22L between the runway threshold and taxiway Y9, NASE conducted several tests. This reports describes our findings. Based on the location of terminals A, B/C and runway 4R/22L, an aligned aerial photo was used to identify several primary reflectors. (Figure 2) Terminal B/C is half way between terminal A and runway 4R/22L (~900 ft) For this test the false radar returns on Y3 was selected. The possible primary reflectors include the Jet way on Gates B3 and B5, and terminal B/C(Figure 3) As the Jet way on Gate B3 was maneuvered, raw radar video was recorded. The ASDE-X displays at the tower and the ASDE-3X manger were used to see the effect of the Jet way on the false target at the intersection of 4R/22L and Y3. Figure 4 shows the radar video during Normal operation As the Jet way was closed (moved towards the building), the size and the amplitude of the radar returns was reduced. It did not completely disappear. See Figures 5 As the Jet way was opened (moved away from the building), the false target returns became bigger. Figure 7 Conclusion: The Jet way did not completely eliminate the false returns but its movement towards and away from the building affected the size and amplitude of the false target. Based on this tests, terminal B/C was identified as the primary reflector for the false targets on runway 4R/22L . The attached playback(DTW_093009_TXYY3_Falsetarget.zip ) shows the system track (cat10) and the radar extent during the testing. The radar extent shows the radar returns footprint as the jet way moved. The second report discusses possible solutions

3. Terminal B/C Radar hitting Terminal B/C Terminal A TWY Y4 TWY Y3 Reflection from Terminal A RWY 4R/22L

4. False target Y3 A5 False target Y4 B3 B1

9. DTW False target solution Since terminal B/C was identified as the Primary reflector for the false targets on runway 4R/22L, it becomes nearly impossible to eliminate all of the false targets from the runway with out major changes. Depending on the position of the Jet ways, basically the structure that is facing terminal A can become primary reflector. This section looks at the possible way of mitigating the effects of the false radar targets. 1. To leave the system in its present form: The system was optimized to declare all tracks that start inside the false reflection area as false targets. Targets that start in side these areas need to satisfy certain parameters before they can be declared real targets. For the most part this changes are effective in eliminating static false targets. Unfortunately, as SMR only targets stop or taxi (slow moving vehicles) near or on top of the false targets, sometime the system will display the false targets as real. The SMR only targets and the false return will merge and the SMR only target‘s system track gets stolen by the false return. Consequently, the false return will be displayed as a real track with a high existence confidence (eligible for safety logic alert) and the vehicle will temporarily be declared false target. Once the vehicles satisfy region parameters, theywill be displayed as real targets. We have several of these incidents. For an example of this, see the attached avi. The only know solution that will completely prevent these type of alerts will degrade radar performance. The radar thresholds on the affected areas can be raise above the false target’s radar returns . This will lead to radar holes. Vehicle that stop at the false radar locations will be thresholded out/removed from display. Vehicles that drive through the affected areas will be affected for brief periods. These can be applied sparingly on runway and taxiway intersection in which vehicle tend to stop or slow down. The intersection of Y3 and Y4 are good examples. The next section will look into this two scenarios. 2.The only known solution that does not degrade the system is for local Air Traffic to manually "Terminate Control" false targets as they appear. Perhaps a combination of the above solutions can help prevent false target. 3 To make change to the surface of the building . This requires applying radar reflectors at specific locations.

10. Small Vehicle test Runs (avi) After temporarily implementing the threshold scenario, the system was tested using a small vehicle. By changing the golden.cmap, the intersection of runway 4R and taxiways Y3 and Y4 were modified to threshold out the radar returns (See Figure 8) DTW_093009_VehilceTest1_Filtering.avi and DTW_093009_VehilceTest2_Filtering.avi show the results of the test. Test 1: As the vehicle (cat11 #2128 ) drove over the area (taxiway Y4), it lost radar support for 2 seconds (15:19:30-32) and it disappeared from display for 1 second (15:19:33) . The vehicle was not affected by the changes on taxiway Y3. Test 2: Two vehicles approach taxiway Y3 and Y4. As Cat11#2128 reached taxiway Y3, loss radar support and disappeared from display 3 seconds latter. The vehicle was instructed to stop on top of the thresholdedarea. Cat#2136 lost radar support for 8 scan and disappeared from display for that long. DTW_093009_TXYY3_Falsetarget.avi : This depicts the current state of the system. All thresholding are removed. At 15:32:40 Vehicle stops near false target (4R/Y4); At 15:35:30, Vehicle merges with false target; At 15:38:00 Vehicle moves away from false target. False target becomes real target with high existence confidence while the vehicle is briefly declared MP. Once it meets system parameters, the vehicle becomes real. Unless AT Manually terminates the “false target” on taxiway Y4, it will generate a false alert with Arrivals and Departures.