Narrative:

This is an ongoing situation at atl ARTCC sector #18, frequency 134.8. The primary and secondary main transmitter/receiver are constantly going out, leaving the sector to operate on the buec backup system. What has prompted this report is a situation that occurred on 4/thu/91, 13.5 NM south of the toccoa airport, GA. With the main radios, coverage exists almost to the ground around the vicinity of the airport. But with the buec, the radio coverage diminishes somewhere around 20 NM south of TOC airport below 4000' MSL. Small aircraft X was en route from macon, GA, to TOC on an IFR flight plan at 5000' MSL. At or about xx:45Z, small aircraft X cancelled IFR and requested VFR5 advisories 25 NM south of TOC. As small aircraft X began its VFR descent to TOC, I noticed VFR traffic head-on at 2700' MSL. When attempting to advise small aircraft X of traffic, I was unable to reach him because the buec was inadequate at his altitude. I continued to attempt radio communication and finally saw the 2 targets merge at 2700' MSL, 13.5 NM south of TOC. I am very aware that pilots are supposed to see and avoid, especially when they are VFR. However, as a controller, it is my duty and responsibility to provide the safe flow of traffic and enhance that safety when possible. Due to a continued equipment problem, I was unable to enhance the see and avoid by not being able to alert a pilot of potential traffic he is expecting me to issue. After I saw the targets pass, I experienced great relief. I do not know if the pilots saw each other, but I do know that if I had proper working radios, I could have advised small aircraft X of head-on traffic. Callback conversation with reporter revealed the following: reporter gave ATC experience. Said that many ucr's have been filed on this problem. Last ucr was by the reporter when this incident occurred. TOC is located approximately 80 mi northeast of atl. The problem with the main and secondary equipment is a microwave dish that continuously gets out of alignment. The buec system is located in another area, thereby not providing the same overlapping radio coverage. There are 2 VHF frequencys that are involved, 134.8 and 121.35, plus UHF. Reporter says this is an old problem. Main and standby radio equipment were being worked on 2 days last week to try to fix it again, but the problem still exists. Reporter says the buec system is used more than the main and standby equipment. The incident occurred just after the aircraft cancelled IFR.

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Original NASA ASRS Text

Title: CTLR COMPLAINS ABOUT RADIO COVERAGE ON BUEC SYSTEM VERSUS PRIMARY RADIO SYSTEM. CTLR REPORTER WITNESSES MERGING TARGETS AND UNABLE TO ISSUE TRAFFIC.

Narrative: THIS IS AN ONGOING SITUATION AT ATL ARTCC SECTOR #18, FREQ 134.8. THE PRIMARY AND SECONDARY MAIN XMITTER/RECEIVER ARE CONSTANTLY GOING OUT, LEAVING THE SECTOR TO OPERATE ON THE BUEC BACKUP SYS. WHAT HAS PROMPTED THIS RPT IS A SITUATION THAT OCCURRED ON 4/THU/91, 13.5 NM S OF THE TOCCOA ARPT, GA. WITH THE MAIN RADIOS, COVERAGE EXISTS ALMOST TO THE GND AROUND THE VICINITY OF THE ARPT. BUT WITH THE BUEC, THE RADIO COVERAGE DIMINISHES SOMEWHERE AROUND 20 NM S OF TOC ARPT BELOW 4000' MSL. SMA X WAS ENRTE FROM MACON, GA, TO TOC ON AN IFR FLT PLAN AT 5000' MSL. AT OR ABOUT XX:45Z, SMA X CANCELLED IFR AND REQUESTED VFR5 ADVISORIES 25 NM S OF TOC. AS SMA X BEGAN ITS VFR DSNT TO TOC, I NOTICED VFR TFC HEAD-ON AT 2700' MSL. WHEN ATTEMPTING TO ADVISE SMA X OF TFC, I WAS UNABLE TO REACH HIM BECAUSE THE BUEC WAS INADEQUATE AT HIS ALT. I CONTINUED TO ATTEMPT RADIO COM AND FINALLY SAW THE 2 TARGETS MERGE AT 2700' MSL, 13.5 NM S OF TOC. I AM VERY AWARE THAT PLTS ARE SUPPOSED TO SEE AND AVOID, ESPECIALLY WHEN THEY ARE VFR. HOWEVER, AS A CTLR, IT IS MY DUTY AND RESPONSIBILITY TO PROVIDE THE SAFE FLOW OF TFC AND ENHANCE THAT SAFETY WHEN POSSIBLE. DUE TO A CONTINUED EQUIP PROB, I WAS UNABLE TO ENHANCE THE SEE AND AVOID BY NOT BEING ABLE TO ALERT A PLT OF POTENTIAL TFC HE IS EXPECTING ME TO ISSUE. AFTER I SAW THE TARGETS PASS, I EXPERIENCED GREAT RELIEF. I DO NOT KNOW IF THE PLTS SAW EACH OTHER, BUT I DO KNOW THAT IF I HAD PROPER WORKING RADIOS, I COULD HAVE ADVISED SMA X OF HEAD-ON TFC. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR GAVE ATC EXPERIENCE. SAID THAT MANY UCR'S HAVE BEEN FILED ON THIS PROB. LAST UCR WAS BY THE RPTR WHEN THIS INCIDENT OCCURRED. TOC IS LOCATED APPROX 80 MI NE OF ATL. THE PROB WITH THE MAIN AND SECONDARY EQUIP IS A MICROWAVE DISH THAT CONTINUOUSLY GETS OUT OF ALIGNMENT. THE BUEC SYS IS LOCATED IN ANOTHER AREA, THEREBY NOT PROVIDING THE SAME OVERLAPPING RADIO COVERAGE. THERE ARE 2 VHF FREQS THAT ARE INVOLVED, 134.8 AND 121.35, PLUS UHF. RPTR SAYS THIS IS AN OLD PROB. MAIN AND STANDBY RADIO EQUIP WERE BEING WORKED ON 2 DAYS LAST WK TO TRY TO FIX IT AGAIN, BUT THE PROB STILL EXISTS. RPTR SAYS THE BUEC SYS IS USED MORE THAN THE MAIN AND STANDBY EQUIP. THE INCIDENT OCCURRED JUST AFTER THE ACFT CANCELLED IFR.

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.