Narrative:

Air carrier Z was at FL310 eastbound awaiting higher when by air carrier Y there was 1 NORDO aircraft in the sector. Severe WX with tops to FL410 from lit-cle. Air carrier X at FL330 inbound to ind was put on a north heading to get around aircraft in order to descend. Air carrier Y was vectored for spacing to dtw. There were 4 aircraft (of the 16 on the sector frequency at the time) being spaced to dtw. There was a lot of frequency bleedthrough on the r-side. Air carrier X was issued FL240, air carrier Y took the clearance for air carrier X. On the frequency, it sounded like air carrier X. The d-side tape was much clearer than the r-side. When the mode C on air carrier Y showed below FL330 I inquired as to what he was doing. I then cleared him to climb immediately to FL330 and issued the traffic below him at FL310, air carrier Z. Afterwards, air carrier X was issued FL240 and he said he was confused about the earlier clearance, but elected not to say anything. I feel that if the pilot on air carrier X was confused about the clearance, then it was inexcusable of him to say nothing. The pilot on air carrier Y should have paid closer attention and not taken the clearance for someone else. The lousy frequency equipment was a contributing factor. Supplemental information from acn 337488: 2 factors that come into the picture are the similar sounding call signs and the clarity of the control frequencys. The control frequencys were usable, but with new equipment how much clearer would the readback have been? The similar sounding call signs were turned into the traffic management unit to contact the company about a change of call sign.

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Original NASA ASRS Text

Title: OPERROR OCCURRED WHEN RPTR ISSUED DSCNT CLRNC FOR ACR X TO DSND TO FL240 FROM FL330. ACR Y, SAME COMPANY WITH SIMILAR CALL SIGNS, ACKNOWLEDGED THE READBACK AND BEGAN DSCNT. ACR Y'S DSCNT CONFLICTED WITH ACR Z AT FL310. RPTR ALLEGED THAT DUE TO A FREQ BLEEDTHROUGH, ACR Y CALL SIGNS SOUNDED LIKE ACR X'S. PLTDEV.

Narrative: ACR Z WAS AT FL310 EBOUND AWAITING HIGHER WHEN BY ACR Y THERE WAS 1 NORDO ACFT IN THE SECTOR. SEVERE WX WITH TOPS TO FL410 FROM LIT-CLE. ACR X AT FL330 INBOUND TO IND WAS PUT ON A N HDG TO GET AROUND ACFT IN ORDER TO DSND. ACR Y WAS VECTORED FOR SPACING TO DTW. THERE WERE 4 ACFT (OF THE 16 ON THE SECTOR FREQ AT THE TIME) BEING SPACED TO DTW. THERE WAS A LOT OF FREQ BLEEDTHROUGH ON THE R-SIDE. ACR X WAS ISSUED FL240, ACR Y TOOK THE CLRNC FOR ACR X. ON THE FREQ, IT SOUNDED LIKE ACR X. THE D-SIDE TAPE WAS MUCH CLEARER THAN THE R-SIDE. WHEN THE MODE C ON ACR Y SHOWED BELOW FL330 I INQUIRED AS TO WHAT HE WAS DOING. I THEN CLRED HIM TO CLB IMMEDIATELY TO FL330 AND ISSUED THE TFC BELOW HIM AT FL310, ACR Z. AFTERWARDS, ACR X WAS ISSUED FL240 AND HE SAID HE WAS CONFUSED ABOUT THE EARLIER CLRNC, BUT ELECTED NOT TO SAY ANYTHING. I FEEL THAT IF THE PLT ON ACR X WAS CONFUSED ABOUT THE CLRNC, THEN IT WAS INEXCUSABLE OF HIM TO SAY NOTHING. THE PLT ON ACR Y SHOULD HAVE PAID CLOSER ATTN AND NOT TAKEN THE CLRNC FOR SOMEONE ELSE. THE LOUSY FREQ EQUIP WAS A CONTRIBUTING FACTOR. SUPPLEMENTAL INFO FROM ACN 337488: 2 FACTORS THAT COME INTO THE PICTURE ARE THE SIMILAR SOUNDING CALL SIGNS AND THE CLARITY OF THE CTL FREQS. THE CTL FREQS WERE USABLE, BUT WITH NEW EQUIP HOW MUCH CLEARER WOULD THE READBACK HAVE BEEN? THE SIMILAR SOUNDING CALL SIGNS WERE TURNED INTO THE TFC MGMNT UNIT TO CONTACT THE COMPANY ABOUT A CHANGE OF CALL SIGN.

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.