Narrative:

We were in cruise flight at FL280 and experiencing light and progressively more light to moderate turbulence. We asked ZTL if they had any ride reports at FL260 and they responded with 'no complaints, descend and maintain FL260.' the first officer responded with, 'ok, we'll go down and give it a try, air carrier abc out of 280 for 260.' approximately 1 min later center asked us what our altitude was and I responded with 'passing 270 for 260.' ZTL responded with a statement that we were supposed to be at FL280 and to make an immediate right turn to FL270. Another aircraft was given a turn to the east and I could see him about 5 or more mi away. After the confusion got squared away and we got further clearance to FL260, I noticed another aircraft on the frequency with a # somewhat like ours. It appears that the controller gave the descent to another aircraft in his mind at the time he was answering us and the other aircraft did not respond because he thought the clearance was for us. The controller was busy and it appears he got the language and call signs confused in his mind. There is an increasing problem today in similar or same call signs and frequency blockage because of too many aircraft on the same frequency. Supplemental information from acn 139701: a few mins later the controller asked another flight his altitude. The call sign was something similar like acd aed or pqcd. His reply was FL280. The controller then asked if they had received their clearance to FL260. Their response was negative. We were reassigned FL260 prior to turning back on our original course. When we left that frequency the controller said sorry for all the confusion. I feel the controller was busy and probably thinking about descending the other flight with the somewhat similar call sign when we called with our request, and bingo!

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Original NASA ASRS Text

Title: ARTCC RADAR CTLR AT ZTL ISSUES DESCENT CLRNC TO WRONG ACFT DUE TO SIMILAR SOUNDING CALL SIGNS. SEPARATION NOT LOST.

Narrative: WE WERE IN CRUISE FLT AT FL280 AND EXPERIENCING LIGHT AND PROGRESSIVELY MORE LIGHT TO MODERATE TURB. WE ASKED ZTL IF THEY HAD ANY RIDE RPTS AT FL260 AND THEY RESPONDED WITH 'NO COMPLAINTS, DSND AND MAINTAIN FL260.' THE F/O RESPONDED WITH, 'OK, WE'LL GO DOWN AND GIVE IT A TRY, ACR ABC OUT OF 280 FOR 260.' APPROX 1 MIN LATER CENTER ASKED US WHAT OUR ALT WAS AND I RESPONDED WITH 'PASSING 270 FOR 260.' ZTL RESPONDED WITH A STATEMENT THAT WE WERE SUPPOSED TO BE AT FL280 AND TO MAKE AN IMMEDIATE RIGHT TURN TO FL270. ANOTHER ACFT WAS GIVEN A TURN TO THE E AND I COULD SEE HIM ABOUT 5 OR MORE MI AWAY. AFTER THE CONFUSION GOT SQUARED AWAY AND WE GOT FURTHER CLRNC TO FL260, I NOTICED ANOTHER ACFT ON THE FREQ WITH A # SOMEWHAT LIKE OURS. IT APPEARS THAT THE CTLR GAVE THE DSCNT TO ANOTHER ACFT IN HIS MIND AT THE TIME HE WAS ANSWERING US AND THE OTHER ACFT DID NOT RESPOND BECAUSE HE THOUGHT THE CLRNC WAS FOR US. THE CTLR WAS BUSY AND IT APPEARS HE GOT THE LANGUAGE AND CALL SIGNS CONFUSED IN HIS MIND. THERE IS AN INCREASING PROB TODAY IN SIMILAR OR SAME CALL SIGNS AND FREQ BLOCKAGE BECAUSE OF TOO MANY ACFT ON THE SAME FREQ. SUPPLEMENTAL INFO FROM ACN 139701: A FEW MINS LATER THE CTLR ASKED ANOTHER FLT HIS ALT. THE CALL SIGN WAS SOMETHING SIMILAR LIKE ACD AED OR PQCD. HIS REPLY WAS FL280. THE CTLR THEN ASKED IF THEY HAD RECEIVED THEIR CLRNC TO FL260. THEIR RESPONSE WAS NEGATIVE. WE WERE REASSIGNED FL260 PRIOR TO TURNING BACK ON OUR ORIGINAL COURSE. WHEN WE LEFT THAT FREQ THE CTLR SAID SORRY FOR ALL THE CONFUSION. I FEEL THE CTLR WAS BUSY AND PROBABLY THINKING ABOUT DSNDING THE OTHER FLT WITH THE SOMEWHAT SIMILAR CALL SIGN WHEN WE CALLED WITH OUR REQUEST, AND BINGO!

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.