Narrative:

Our flight number for this leg was abc. We departed mem directly behind another eastbound company heavy aircraft whose flight number was air data computer. We were very aware of the similarities, and each control facility advised us that company flight air data computer was also on the frequency. When we xferred to the memphis low sector we were cleared to FL230. Prior to handing us off to the high sector, we were advised that they were very saturated and that we might be held at FL230 for a short while. We heard a frequency change for what sounded like our flight number, however, there was enough ambiguity in the syntax that we questioned which aircraft the change was for, and were advised that the change was for air data computer. A few mins later, we were handed off to ZME high sector. When we checked in, we were cleared to maintain FL230, and were again advised that company flight air data computer was also on this frequency. About 4 mins later we acknowledged a clearance to climb and maintain FL330. It is important to note that as we were anticipating being at FL230 for an extended length of time, there were no preconceived expectations to receive this clearance. As well, as PF, I set the new altitude in the fcp window at the same time as the first officer acknowledged receiving the clearance. The point is that there were no distrs, we were vigilant that a similar call sign was on the frequency, and there was no ambiguity as happened in the cited frequency change. The first officer and I both independently heard what sounded like a clearance for abc to climb and maintain FL330. After acknowledging the clearance we began the climb to FL330. There was no challenge to our acknowledgement by either ZME or any other aircraft. As we passed through approximately FL265 we were queried about our climb by ZME. We informed them that we were climbing to FL330 per our clearance. We were advised that the climb clearance was intended for flight air data computer. After a brief moment of silence, we asked center where they would like us. We were subsequently cleared to maintain FL270. At this point it is unclr whether ZME or we committed the error. In any event, our company is well aware that they often place flts with virtually indistinguishable flight numbers in close proximity. They acknowledge that this is a safety issue, yet they have done very little to resolve this concern.

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Original NASA ASRS Text

Title: ENRTE A300 CONFUSED CALL SIGN AND STARTED CLB WITHOUT ATC CLRNC.

Narrative: OUR FLT NUMBER FOR THIS LEG WAS ABC. WE DEPARTED MEM DIRECTLY BEHIND ANOTHER EBOUND COMPANY HVY ACFT WHOSE FLT NUMBER WAS ADC. WE WERE VERY AWARE OF THE SIMILARITIES, AND EACH CTL FACILITY ADVISED US THAT COMPANY FLT ADC WAS ALSO ON THE FREQ. WHEN WE XFERRED TO THE MEMPHIS LOW SECTOR WE WERE CLRED TO FL230. PRIOR TO HANDING US OFF TO THE HIGH SECTOR, WE WERE ADVISED THAT THEY WERE VERY SATURATED AND THAT WE MIGHT BE HELD AT FL230 FOR A SHORT WHILE. WE HEARD A FREQ CHANGE FOR WHAT SOUNDED LIKE OUR FLT NUMBER, HOWEVER, THERE WAS ENOUGH AMBIGUITY IN THE SYNTAX THAT WE QUESTIONED WHICH ACFT THE CHANGE WAS FOR, AND WERE ADVISED THAT THE CHANGE WAS FOR ADC. A FEW MINS LATER, WE WERE HANDED OFF TO ZME HIGH SECTOR. WHEN WE CHKED IN, WE WERE CLRED TO MAINTAIN FL230, AND WERE AGAIN ADVISED THAT COMPANY FLT ADC WAS ALSO ON THIS FREQ. ABOUT 4 MINS LATER WE ACKNOWLEDGED A CLRNC TO CLB AND MAINTAIN FL330. IT IS IMPORTANT TO NOTE THAT AS WE WERE ANTICIPATING BEING AT FL230 FOR AN EXTENDED LENGTH OF TIME, THERE WERE NO PRECONCEIVED EXPECTATIONS TO RECEIVE THIS CLRNC. AS WELL, AS PF, I SET THE NEW ALT IN THE FCP WINDOW AT THE SAME TIME AS THE FO ACKNOWLEDGED RECEIVING THE CLRNC. THE POINT IS THAT THERE WERE NO DISTRS, WE WERE VIGILANT THAT A SIMILAR CALL SIGN WAS ON THE FREQ, AND THERE WAS NO AMBIGUITY AS HAPPENED IN THE CITED FREQ CHANGE. THE FO AND I BOTH INDEPENDENTLY HEARD WHAT SOUNDED LIKE A CLRNC FOR ABC TO CLB AND MAINTAIN FL330. AFTER ACKNOWLEDGING THE CLRNC WE BEGAN THE CLB TO FL330. THERE WAS NO CHALLENGE TO OUR ACKNOWLEDGEMENT BY EITHER ZME OR ANY OTHER ACFT. AS WE PASSED THROUGH APPROX FL265 WE WERE QUERIED ABOUT OUR CLB BY ZME. WE INFORMED THEM THAT WE WERE CLBING TO FL330 PER OUR CLRNC. WE WERE ADVISED THAT THE CLB CLRNC WAS INTENDED FOR FLT ADC. AFTER A BRIEF MOMENT OF SILENCE, WE ASKED CTR WHERE THEY WOULD LIKE US. WE WERE SUBSEQUENTLY CLRED TO MAINTAIN FL270. AT THIS POINT IT IS UNCLR WHETHER ZME OR WE COMMITTED THE ERROR. IN ANY EVENT, OUR COMPANY IS WELL AWARE THAT THEY OFTEN PLACE FLTS WITH VIRTUALLY INDISTINGUISHABLE FLT NUMBERS IN CLOSE PROX. THEY ACKNOWLEDGE THAT THIS IS A SAFETY ISSUE, YET THEY HAVE DONE VERY LITTLE TO RESOLVE THIS CONCERN.

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.