|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||0601 To 1200|
|Locale Reference||atc facility : sli|
airport : sna
|Altitude||msl bound lower : 2000|
msl bound upper : 13000
|Controlling Facilities||tracon : sna|
|Make Model Name||Any Unknown or Unlisted Aircraft Manufacturer|
|Affiliation||government : faa|
|Function||controller : approach|
|Qualification||controller : radar|
|Experience||controller military : 8|
controller radar : 10
|Function||flight crew : single pilot|
|Qualification||pilot : instrument|
|Anomaly||other anomaly other|
|Independent Detector||other controllera|
|Resolutory Action||none taken : unable|
|Miss Distance||horizontal : 3000|
vertical : 100
|Primary Problem||ATC Human Performance|
|Air Traffic Incident||other|
|ATC Facility||other physical facility|
Blind spot over sli VORTAC approximately 3 1/2 mi radius. On more than one occasion, I have had pilots of both VFR and IFR aircraft report near misses with aircraft in this blind spot, some requiring evasive action. In nearly all cases, the pilot(south) want to know why I didn't call the traffic. Of course, I never saw the traffic. On at least one occasion, the civil aircraft (VFR, not talking to me) who caused the near miss could not be seen entering the blind spot even on the radar playback. These VFR aircraft are not required to call me, this would be no problem if I could see them. The real problem, in my opinion, is that pilots are unaware that they (and potential conflicting traffic) are not in radar contact for about 7 flight mi over the VORTAC. They trust me to call the traffic for them. The same problem exists over nzj VORTAC. Military jets departing nzj execute a right climbing turn over the VORTAC to 13000. On more than one occasion, they have busted their altitude restriction, and the controller couldn't catch it or warn ZLA because aircraft was in blind spot. Callback conversation with reporter revealed the following information. Call to facility revealed that both VORTAC's are in the same location as the radar antenna's and that loss of radar does occur as the reporter states. This is common to all radar antenna sites. When loss of radar occurs, the controller is required to advise the pilot. There are no IFR routing procedures that take aircraft over either VORTAC, however, they do have a lot of VFR traffic in the vicinity of sli VORTAC. The radar antenna at sli is an ASR-8, but will soon be upgraded to an ASR-9. The facility has no plans to change procedures.
Original NASA ASRS Text
Title: CTLR STATES THAT THERE IS A RADAR BLIND SPOT OVER SLI VORTAC THAT ALLEGEDLY IMPACTS SAFETY.
Narrative: BLIND SPOT OVER SLI VORTAC APPROX 3 1/2 MI RADIUS. ON MORE THAN ONE OCCASION, I HAVE HAD PLTS OF BOTH VFR AND IFR ACFT RPT NEAR MISSES WITH ACFT IN THIS BLIND SPOT, SOME REQUIRING EVASIVE ACTION. IN NEARLY ALL CASES, THE PLT(S) WANT TO KNOW WHY I DIDN'T CALL THE TFC. OF COURSE, I NEVER SAW THE TFC. ON AT LEAST ONE OCCASION, THE CIVIL ACFT (VFR, NOT TALKING TO ME) WHO CAUSED THE NEAR MISS COULD NOT BE SEEN ENTERING THE BLIND SPOT EVEN ON THE RADAR PLAYBACK. THESE VFR ACFT ARE NOT REQUIRED TO CALL ME, THIS WOULD BE NO PROBLEM IF I COULD SEE THEM. THE REAL PROBLEM, IN MY OPINION, IS THAT PLTS ARE UNAWARE THAT THEY (AND POTENTIAL CONFLICTING TFC) ARE NOT IN RADAR CONTACT FOR ABOUT 7 FLT MI OVER THE VORTAC. THEY TRUST ME TO CALL THE TFC FOR THEM. THE SAME PROBLEM EXISTS OVER NZJ VORTAC. MIL JETS DEPARTING NZJ EXECUTE A R CLBING TURN OVER THE VORTAC TO 13000. ON MORE THAN ONE OCCASION, THEY HAVE BUSTED THEIR ALT RESTRICTION, AND THE CTLR COULDN'T CATCH IT OR WARN ZLA BECAUSE ACFT WAS IN BLIND SPOT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. CALL TO FACILITY REVEALED THAT BOTH VORTAC'S ARE IN THE SAME LOCATION AS THE RADAR ANTENNA'S AND THAT LOSS OF RADAR DOES OCCUR AS THE RPTR STATES. THIS IS COMMON TO ALL RADAR ANTENNA SITES. WHEN LOSS OF RADAR OCCURS, THE CTLR IS REQUIRED TO ADVISE THE PLT. THERE ARE NO IFR ROUTING PROCS THAT TAKE ACFT OVER EITHER VORTAC, HOWEVER, THEY DO HAVE A LOT OF VFR TFC IN THE VICINITY OF SLI VORTAC. THE RADAR ANTENNA AT SLI IS AN ASR-8, BUT WILL SOON BE UPGRADED TO AN ASR-9. THE FACILITY HAS NO PLANS TO CHANGE PROCS.
Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.