Narrative:

Air carrier X and air carrier Y entered my airspace 10 mi in trail at 17000'. Both were slowed to 250 KTS along with 2 more rdu arrs. I turned both aircraft to 190 degree heading for spacing along with the third arrival, and descended them to 16000'. These aircraft were on 132.55 (sector 23 frequency) because the normal sector 24 frequency (123.85) had a stuck microphone. After turning air carrier X to 280 degrees to join the arrival route, I noticed air carrier Y was no longer on the 190 degree heading and tried to put him back on the 190 degree heading but could not contact him. The frequency coverage was not sufficient on 132.55. I then tried to reach X but had lost him as well. I then had #4 aircraft broadcast for air carrier X to come up on the next sector's (sector 28) frequency and when he did they descended him and re-established sep with air carrier Y. Each sector should have a back up frequency that can cover the entire area. Supplemental information from acn 99436: air carrier X and air carrier Y were inbound to raleigh on converging courses being worked by sector 24. X was on V66 and Y on V615. Sector 24 lost his frequency and combined with sector 23 because there were no spare frequencys. Air carrier Y was descended to 16000' and given a heading to go behind X. Air carrier X was already at 16000' to make altitude and spacing requirements for the next sector. X and Y were approaching the radio limits of sector 23 and X aircraft was given a heading, but Y acknowledged the turn. Radio contact was lost before it could be corrected. Our radio equipment failed much too often. It took almost 5 mins to re-establish radio contact. This time we were lucky. Supplemental information from acn 101166: adjacent sector sequencing approximately 10 arrs to rdu. After in trail spacing established they are handed off to our sector for final descent and speed reduction to approach control. Rdu is a hub for abc airlines with several arrival flows and departures daily. During these intense flows as many as 20 aircraft on same frequency. All with abc call signs. One abc aircraft took a clearance for another abc aircraft, which put him on a converging course at same altitude.

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Original NASA ASRS Text

Title: RADIO COM PROBLEM RESULTS IN LESS THAN STANDARD SEPARATION BETWEEN 2 ACR. OPERATIONAL ERROR.

Narrative: ACR X AND ACR Y ENTERED MY AIRSPACE 10 MI IN TRAIL AT 17000'. BOTH WERE SLOWED TO 250 KTS ALONG WITH 2 MORE RDU ARRS. I TURNED BOTH ACFT TO 190 DEG HDG FOR SPACING ALONG WITH THE THIRD ARR, AND DSNDED THEM TO 16000'. THESE ACFT WERE ON 132.55 (SECTOR 23 FREQ) BECAUSE THE NORMAL SECTOR 24 FREQ (123.85) HAD A STUCK MIC. AFTER TURNING ACR X TO 280 DEGS TO JOIN THE ARR ROUTE, I NOTICED ACR Y WAS NO LONGER ON THE 190 DEG HDG AND TRIED TO PUT HIM BACK ON THE 190 DEG HDG BUT COULD NOT CONTACT HIM. THE FREQ COVERAGE WAS NOT SUFFICIENT ON 132.55. I THEN TRIED TO REACH X BUT HAD LOST HIM AS WELL. I THEN HAD #4 ACFT BROADCAST FOR ACR X TO COME UP ON THE NEXT SECTOR'S (SECTOR 28) FREQ AND WHEN HE DID THEY DSNDED HIM AND RE-ESTABLISHED SEP WITH ACR Y. EACH SECTOR SHOULD HAVE A BACK UP FREQ THAT CAN COVER THE ENTIRE AREA. SUPPLEMENTAL INFO FROM ACN 99436: ACR X AND ACR Y WERE INBND TO RALEIGH ON CONVERGING COURSES BEING WORKED BY SECTOR 24. X WAS ON V66 AND Y ON V615. SECTOR 24 LOST HIS FREQ AND COMBINED WITH SECTOR 23 BECAUSE THERE WERE NO SPARE FREQS. ACR Y WAS DSNDED TO 16000' AND GIVEN A HDG TO GO BEHIND X. ACR X WAS ALREADY AT 16000' TO MAKE ALT AND SPACING REQUIREMENTS FOR THE NEXT SECTOR. X AND Y WERE APCHING THE RADIO LIMITS OF SECTOR 23 AND X ACFT WAS GIVEN A HDG, BUT Y ACKNOWLEDGED THE TURN. RADIO CONTACT WAS LOST BEFORE IT COULD BE CORRECTED. OUR RADIO EQUIP FAILED MUCH TOO OFTEN. IT TOOK ALMOST 5 MINS TO RE-ESTABLISH RADIO CONTACT. THIS TIME WE WERE LUCKY. SUPPLEMENTAL INFO FROM ACN 101166: ADJACENT SECTOR SEQUENCING APPROX 10 ARRS TO RDU. AFTER IN TRAIL SPACING ESTABLISHED THEY ARE HANDED OFF TO OUR SECTOR FOR FINAL DSCNT AND SPD REDUCTION TO APCH CTL. RDU IS A HUB FOR ABC AIRLINES WITH SEVERAL ARR FLOWS AND DEPS DAILY. DURING THESE INTENSE FLOWS AS MANY AS 20 ACFT ON SAME FREQ. ALL WITH ABC CALL SIGNS. ONE ABC ACFT TOOK A CLRNC FOR ANOTHER ABC ACFT, WHICH PUT HIM ON A CONVERGING COURSE AT SAME ALT.

Data retrieved from NASA's ASRS site as of August 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.