Narrative:

I was administering OJT at the time to a developmental radar trainee. Air carrier X on initial call-up requested 160 as his final cruising altitude and apparently had difficulty receiving the climb clearance to 160 as he had to ask for a repeat of the clearance. Approximately at the same time, air carrier Y, an medium large transport, hnl-ogg departed climbing to 130. Radar trainee observed air carrier Y as conflicting eastbound traffic for air carrier X and issued clearance to 140 for air carrier X. Air carrier X did not acknowledge the first clearance and trainee repeated the clearance to 140. Pilot of air carrier X apparently heard and read back 100 as the assigned altitude. Trainee and myself heard '140' as the reply. Tape of incident reveals that our radio receiver or aircraft transmitter broke up just as he was reading back the altitude in single digits and comes across as 'one (unintelligible) thousand' on readback. Air carrier Y on initial call-up level at 130 to us, was issued traffic (air carrier X) at 12 O'clock, 7 mi, wbound company medium large transport leaving 14,500 for 140, and pilot of air carrier Y called this traffic in sight. Air carrier X was then issued a 250 KT restriction and on his readback 'called out of 13,500 for 10,000' which alerted us to the confliction. Trainee then took immediate action by turning air carrier X to a 180 degree heading and air carrier Y to a 060 degree heading. My supervisor said that the cdr readout showed the closest distance the two aircraft came were 2 1/2 mi and 100'. Radio frequencys -- both transmitters and receivers -- have been less than satisfactory for months at the cerap, and I believe that this factor contributed to the incident. Something may have also been wrong with the pilot's radio since he missed two clrncs, and since the jets are routinely assigned 100 west of lny prior to handoff to hnl approach, pilot may have been expecting a clearance to 100 and out of habit read back 100. Since our receiver was also bad, it broke up at a critical moment, but just enough so we heard '14,000' on the readback. Supplemental information from acn 134345: air carrier X cruising at 16,000, we received descent clearance. The controller's instructions were broken, and we read back the clearance and told the controller his transmission was broken. His reply, 'how do you read me now'. Our reply 'loud and clear'. A normal descent clearance would be, cleared to cross julle at or below 14,000 to maintain 10,000. This is the clearance we read back. The controller did not acknowledge anything but :how do you read this transmission.' we started our descent and reported leaving 16,000. Descending through 14,000' we heard the controller give traffic to company, opposite direction at 13,000' (i.e., company traffic opposite direction at 14,000). Realizing that we were that traffic, we stopped the descent at 13,500' and asked the controller what altitude he wanted us at. He said maintain 13,500 and turn left 180 and gave company a heading of 090. The controller never clarified the misunderstanding. I did call center, and found out that a student controller was on duty with a supervisor and apparently both missed our readback or didn't hear it.

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Original NASA ASRS Text

Title: ACR X HAD LESS THAN STANDARD SEPARATION FROM ACR Y. SYSTEM ERROR.

Narrative: I WAS ADMINISTERING OJT AT THE TIME TO A DEVELOPMENTAL RADAR TRAINEE. ACR X ON INITIAL CALL-UP REQUESTED 160 AS HIS FINAL CRUISING ALT AND APPARENTLY HAD DIFFICULTY RECEIVING THE CLIMB CLRNC TO 160 AS HE HAD TO ASK FOR A REPEAT OF THE CLRNC. APPROX AT THE SAME TIME, ACR Y, AN MLG, HNL-OGG DEPARTED CLIMBING TO 130. RADAR TRAINEE OBSERVED ACR Y AS CONFLICTING EBND TFC FOR ACR X AND ISSUED CLRNC TO 140 FOR ACR X. ACR X DID NOT ACKNOWLEDGE THE FIRST CLRNC AND TRAINEE REPEATED THE CLRNC TO 140. PLT OF ACR X APPARENTLY HEARD AND READ BACK 100 AS THE ASSIGNED ALT. TRAINEE AND MYSELF HEARD '140' AS THE REPLY. TAPE OF INCIDENT REVEALS THAT OUR RADIO RECEIVER OR ACFT TRANSMITTER BROKE UP JUST AS HE WAS READING BACK THE ALT IN SINGLE DIGITS AND COMES ACROSS AS 'ONE (UNINTELLIGIBLE) THOUSAND' ON READBACK. ACR Y ON INITIAL CALL-UP LEVEL AT 130 TO US, WAS ISSUED TFC (ACR X) AT 12 O'CLOCK, 7 MI, WBOUND COMPANY MLG LEAVING 14,500 FOR 140, AND PLT OF ACR Y CALLED THIS TFC IN SIGHT. ACR X WAS THEN ISSUED A 250 KT RESTRICTION AND ON HIS READBACK 'CALLED OUT OF 13,500 FOR 10,000' WHICH ALERTED US TO THE CONFLICTION. TRAINEE THEN TOOK IMMEDIATE ACTION BY TURNING ACR X TO A 180 DEG HDG AND ACR Y TO A 060 DEG HDG. MY SUPVR SAID THAT THE CDR READOUT SHOWED THE CLOSEST DISTANCE THE TWO ACFT CAME WERE 2 1/2 MI AND 100'. RADIO FREQS -- BOTH TRANSMITTERS AND RECEIVERS -- HAVE BEEN LESS THAN SATISFACTORY FOR MONTHS AT THE CERAP, AND I BELIEVE THAT THIS FACTOR CONTRIBUTED TO THE INCIDENT. SOMETHING MAY HAVE ALSO BEEN WRONG WITH THE PLT'S RADIO SINCE HE MISSED TWO CLRNCS, AND SINCE THE JETS ARE ROUTINELY ASSIGNED 100 W OF LNY PRIOR TO HANDOFF TO HNL APCH, PLT MAY HAVE BEEN EXPECTING A CLRNC TO 100 AND OUT OF HABIT READ BACK 100. SINCE OUR RECEIVER WAS ALSO BAD, IT BROKE UP AT A CRITICAL MOMENT, BUT JUST ENOUGH SO WE HEARD '14,000' ON THE READBACK. SUPPLEMENTAL INFORMATION FROM ACN 134345: ACR X CRUISING AT 16,000, WE RECEIVED DSCNT CLRNC. THE CTLR'S INSTRUCTIONS WERE BROKEN, AND WE READ BACK THE CLRNC AND TOLD THE CTLR HIS XMISSION WAS BROKEN. HIS REPLY, 'HOW DO YOU READ ME NOW'. OUR REPLY 'LOUD AND CLEAR'. A NORMAL DSCNT CLRNC WOULD BE, CLRED TO CROSS JULLE AT OR BELOW 14,000 TO MAINTAIN 10,000. THIS IS THE CLRNC WE READ BACK. THE CTLR DID NOT ACKNOWLEDGE ANYTHING BUT :HOW DO YOU READ THIS XMISSION.' WE STARTED OUR DSCNT AND REPORTED LEAVING 16,000. DESCENDING THROUGH 14,000' WE HEARD THE CTLR GIVE TFC TO COMPANY, OPPOSITE DIRECTION AT 13,000' (I.E., COMPANY TFC OPPOSITE DIRECTION AT 14,000). REALIZING THAT WE WERE THAT TFC, WE STOPPED THE DSCNT AT 13,500' AND ASKED THE CTLR WHAT ALT HE WANTED US AT. HE SAID MAINTAIN 13,500 AND TURN LEFT 180 AND GAVE COMPANY A HDG OF 090. THE CTLR NEVER CLARIFIED THE MISUNDERSTANDING. I DID CALL CENTER, AND FOUND OUT THAT A STUDENT CTLR WAS ON DUTY WITH A SUPVR AND APPARENTLY BOTH MISSED OUR READBACK OR DIDN'T HEAR IT.

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.