Narrative:

We were flying air carrier X flight XXXA from rsw to ewr. We were level at FL310, just north of sqt NDB. ZMA gave us a clearance to fly heading 020 degrees until receiving ilm, then direct ilm. ZMA then conducted a changeover briefing because we heard it over their hot microphone. During the brief, I heard the outgoing controller brief the oncoming controller that 'air carrier X flight XXXA was given 020 degrees until receiving ilm, but they have not checked in yet.' I wanted to correct the new controller that we had checked in, but it became apparent he was busy controling several frequencys. A few moments later, I heard the instructions 'air carrier X flight XXXA, I have some parallel traffic, so fly heading 045 degrees to increase separation.' my captain was making a PA to the passenger, so I acknowledged 'air carrier X flight XXXA heading 045 degrees' and complied. I soon noticed that ZMA controller was also controling another air carrier X aircraft on a different frequency with a similar call sign which I believe was flight XXXB. I was concerned that, with similar call signs and simultaneous frequencys, we might have simultaneously acknowledged a 045 degree heading. I wanted to verify that the controller knew I had turned, but I had to wait while he worked another frequency. I finally got through to him and said 'miami, air carrier X flight XXXA, I wanted to make sure you knew that we are level FL310 heading 045 degrees.' he came back with 'air carrier X flight XXXA, fly heading 015 degrees until receiving ilm.' we had been on a 045 degree heading for a couple of mins. During the remaining time with this controller, several flts on different frequencys were probably, unwittingly, calling the controller near simultaneously, and this made his job difficult. This also happened when we were instructed to contact ZJX. I did not see any emerging conflicts on our TCASII while we flew the 045 degree heading. The mia controller made no mention of a heading deviation, if indeed there was one. Obviously, the use of simultaneous frequencys diminishes situational awareness on the part of air crews, and increases controller workload. We listen carefully to the radios, use active noise reduction headsets to mitigate the noisy ambient level of the B737-200 cockpit, and try not to transmit if we think the controller might be busy on another frequency.

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Original NASA ASRS Text

Title: B737-200 CREW HAD ZMA CTLR MIX UP CALL SIGNS. CTLR SHIFT CHANGE WAS TAKING PLACE AT THE TIME.

Narrative: WE WERE FLYING ACR X FLT XXXA FROM RSW TO EWR. WE WERE LEVEL AT FL310, JUST N OF SQT NDB. ZMA GAVE US A CLRNC TO FLY HDG 020 DEGS UNTIL RECEIVING ILM, THEN DIRECT ILM. ZMA THEN CONDUCTED A CHANGEOVER BRIEFING BECAUSE WE HEARD IT OVER THEIR HOT MIKE. DURING THE BRIEF, I HEARD THE OUTGOING CTLR BRIEF THE ONCOMING CTLR THAT 'ACR X FLT XXXA WAS GIVEN 020 DEGS UNTIL RECEIVING ILM, BUT THEY HAVE NOT CHKED IN YET.' I WANTED TO CORRECT THE NEW CTLR THAT WE HAD CHKED IN, BUT IT BECAME APPARENT HE WAS BUSY CTLING SEVERAL FREQS. A FEW MOMENTS LATER, I HEARD THE INSTRUCTIONS 'ACR X FLT XXXA, I HAVE SOME PARALLEL TFC, SO FLY HDG 045 DEGS TO INCREASE SEPARATION.' MY CAPT WAS MAKING A PA TO THE PAX, SO I ACKNOWLEDGED 'ACR X FLT XXXA HDG 045 DEGS' AND COMPLIED. I SOON NOTICED THAT ZMA CTLR WAS ALSO CTLING ANOTHER ACR X ACFT ON A DIFFERENT FREQ WITH A SIMILAR CALL SIGN WHICH I BELIEVE WAS FLT XXXB. I WAS CONCERNED THAT, WITH SIMILAR CALL SIGNS AND SIMULTANEOUS FREQS, WE MIGHT HAVE SIMULTANEOUSLY ACKNOWLEDGED A 045 DEG HDG. I WANTED TO VERIFY THAT THE CTLR KNEW I HAD TURNED, BUT I HAD TO WAIT WHILE HE WORKED ANOTHER FREQ. I FINALLY GOT THROUGH TO HIM AND SAID 'MIAMI, ACR X FLT XXXA, I WANTED TO MAKE SURE YOU KNEW THAT WE ARE LEVEL FL310 HDG 045 DEGS.' HE CAME BACK WITH 'ACR X FLT XXXA, FLY HDG 015 DEGS UNTIL RECEIVING ILM.' WE HAD BEEN ON A 045 DEG HDG FOR A COUPLE OF MINS. DURING THE REMAINING TIME WITH THIS CTLR, SEVERAL FLTS ON DIFFERENT FREQS WERE PROBABLY, UNWITTINGLY, CALLING THE CTLR NEAR SIMULTANEOUSLY, AND THIS MADE HIS JOB DIFFICULT. THIS ALSO HAPPENED WHEN WE WERE INSTRUCTED TO CONTACT ZJX. I DID NOT SEE ANY EMERGING CONFLICTS ON OUR TCASII WHILE WE FLEW THE 045 DEG HDG. THE MIA CTLR MADE NO MENTION OF A HDG DEV, IF INDEED THERE WAS ONE. OBVIOUSLY, THE USE OF SIMULTANEOUS FREQS DIMINISHES SITUATIONAL AWARENESS ON THE PART OF AIR CREWS, AND INCREASES CTLR WORKLOAD. WE LISTEN CAREFULLY TO THE RADIOS, USE ACTIVE NOISE REDUCTION HEADSETS TO MITIGATE THE NOISY AMBIENT LEVEL OF THE B737-200 COCKPIT, AND TRY NOT TO XMIT IF WE THINK THE CTLR MIGHT BE BUSY ON ANOTHER FREQ.

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.