Narrative:

Small aircraft X was at 9000' wbound, wrong altitude for direction of flight 30 mi northeast of psb. Then I got rho on another small aircraft Y approximately 30 mi north of psb also at 9000'. At this time the aircraft were approximately 60 mi apart or almost 10 mins flying time apart. I was visibility radar sep and due to the distance between aircraft, there was no imminent situation at this time. I right away tried to call the wbound aircraft X to change his altitude. He did not respond. He was on frequency 135.75 which is located at abe, approximately 80-90 mi away. (This frequency is normally used in our entire area at 9000' and above when sectors are combined as they were even though it is outside the normal range. We normally use it to reduce confusion of multiple frequency use and it normally works throughout our entire area. However for 2 or 3 days prior to this day the frequency was out for repairs.) when aircraft X did not respond, I tried to call him using the backup radio. After that I told the southbound aircraft Y who was the only aircraft in the area and was on a different frequency, 134.8, to go to frequency 135.75 and transmit to aircraft X to return to my other frequency 134.8 and then return to frequency 134.8 also. Aircraft Y responded asking me to verify the frequency to go to and I repeated the entire information. (At this time aircraft are still 8-9 mins apart, so still no urgency to situation.) after a few mins, when neither aircraft returned to my frequency, I tried to get other aircraft to change frequency and get aircraft X and Y back. I also continued to call both aircraft and issue vectors on all my frequencys, but neither plane could hear me, apparently the frequency was too weak today. The aircraft passed by approximately 3.5 mi then right after aircraft X and Y finally called on frequency 134.8. Aircraft Y stated he couldn't get me on frequency 135.75. I told him he was supposed to get aircraft X and return. He just said he heard aircraft X on other frequency and told him to come to frequency 134.8 now. He obviously misunderstood instructions and just sat on frequency 135.75 for awhile. Controller followed all applicable procedures. Contributing factors were facility procedure of using frequency out of range (even though it usually works), frequency being weak on this date, aircraft Y misunderstanding instructions, both aircraft realizing they were not in radio contact and not taking action to contact me as stated in the aim. Corrective action would be for controllers to try to use frequency within normal limits and for pilots to make sure they understand and follow instructions and also follow normal lost communication procedures.

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Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN 2 SMALL ACFT. BOTH IFR. OPEATIONAL ERROR.

Narrative: SMA X WAS AT 9000' WBOUND, WRONG ALT FOR DIRECTION OF FLT 30 MI NE OF PSB. THEN I GOT RHO ON ANOTHER SMA Y APPROX 30 MI N OF PSB ALSO AT 9000'. AT THIS TIME THE ACFT WERE APPROX 60 MI APART OR ALMOST 10 MINS FLYING TIME APART. I WAS VIS RADAR SEP AND DUE TO THE DISTANCE BTWN ACFT, THERE WAS NO IMMINENT SITUATION AT THIS TIME. I RIGHT AWAY TRIED TO CALL THE WBOUND ACFT X TO CHANGE HIS ALT. HE DID NOT RESPOND. HE WAS ON FREQ 135.75 WHICH IS LOCATED AT ABE, APPROX 80-90 MI AWAY. (THIS FREQ IS NORMALLY USED IN OUR ENTIRE AREA AT 9000' AND ABOVE WHEN SECTORS ARE COMBINED AS THEY WERE EVEN THOUGH IT IS OUTSIDE THE NORMAL RANGE. WE NORMALLY USE IT TO REDUCE CONFUSION OF MULTIPLE FREQ USE AND IT NORMALLY WORKS THROUGHOUT OUR ENTIRE AREA. HOWEVER FOR 2 OR 3 DAYS PRIOR TO THIS DAY THE FREQ WAS OUT FOR REPAIRS.) WHEN ACFT X DID NOT RESPOND, I TRIED TO CALL HIM USING THE BACKUP RADIO. AFTER THAT I TOLD THE SBND ACFT Y WHO WAS THE ONLY ACFT IN THE AREA AND WAS ON A DIFFERENT FREQ, 134.8, TO GO TO FREQ 135.75 AND XMIT TO ACFT X TO RETURN TO MY OTHER FREQ 134.8 AND THEN RETURN TO FREQ 134.8 ALSO. ACFT Y RESPONDED ASKING ME TO VERIFY THE FREQ TO GO TO AND I REPEATED THE ENTIRE INFO. (AT THIS TIME ACFT ARE STILL 8-9 MINS APART, SO STILL NO URGENCY TO SITUATION.) AFTER A FEW MINS, WHEN NEITHER ACFT RETURNED TO MY FREQ, I TRIED TO GET OTHER ACFT TO CHANGE FREQ AND GET ACFT X AND Y BACK. I ALSO CONTINUED TO CALL BOTH ACFT AND ISSUE VECTORS ON ALL MY FREQS, BUT NEITHER PLANE COULD HEAR ME, APPARENTLY THE FREQ WAS TOO WEAK TODAY. THE ACFT PASSED BY APPROX 3.5 MI THEN RIGHT AFTER ACFT X AND Y FINALLY CALLED ON FREQ 134.8. ACFT Y STATED HE COULDN'T GET ME ON FREQ 135.75. I TOLD HIM HE WAS SUPPOSED TO GET ACFT X AND RETURN. HE JUST SAID HE HEARD ACFT X ON OTHER FREQ AND TOLD HIM TO COME TO FREQ 134.8 NOW. HE OBVIOUSLY MISUNDERSTOOD INSTRUCTIONS AND JUST SAT ON FREQ 135.75 FOR AWHILE. CTLR FOLLOWED ALL APPLICABLE PROCS. CONTRIBUTING FACTORS WERE FAC PROC OF USING FREQ OUT OF RANGE (EVEN THOUGH IT USUALLY WORKS), FREQ BEING WEAK ON THIS DATE, ACFT Y MISUNDERSTANDING INSTRUCTIONS, BOTH ACFT REALIZING THEY WERE NOT IN RADIO CONTACT AND NOT TAKING ACTION TO CONTACT ME AS STATED IN THE AIM. CORRECTIVE ACTION WOULD BE FOR CTLRS TO TRY TO USE FREQ WITHIN NORMAL LIMITS AND FOR PLTS TO MAKE SURE THEY UNDERSTAND AND FOLLOW INSTRUCTIONS AND ALSO FOLLOW NORMAL LOST COM PROCS.

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.