Narrative:

As we approached the beginning of the runway we were #1 for takeoff on that side of the runway. The active runway was runway 27. Winds were 080 degrees at 9 KTS. There was an aircraft on the other side of runway 27 holding back about 75 ft from the hold short line. ATC then told us, or so we assumed, that we were cleared for takeoff, turn right heading 330 degrees. We read back our clearance and entered runway 27 for departure. I was busy with checklists when my captain heard a conversation with the aircraft across the runway that made him think we entered the runway by mistake. I asked for confirmation that we were cleared for takeoff and ATC said, 'are you on the runway?' I replied, 'yes.' he said something like, 'ok, you are cleared for takeoff, turn right heading 090 degrees.' the word ok and the new heading of 090 degrees instead of 330 degrees makes me believe we were not cleared onto the runway as I and my captain thought. During takeoff, I heard him clear the aircraft across the runway into position and hold. The other aircraft was flight Y, with similar alpha numeric. Even when he cleared aircraft #2 onto runway 27, I still heard our call sign. I believe the non standard phraseology of, 'oh', the letter instead of 'zero' the number, and our assumption we were the only ones around with a call sign in our number range both led to this possible mistake. We can be more attentive in the future and not 'assume' ATC will tell us similar call signs are on frequency and the age-old problem of non standard phraseology could prevent this in the future.

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Original NASA ASRS Text

Title: RWY 27 INCURSION DURING A CALL SIGN MIX UP WITH 2 ACR'S AWAITING TKOF AT CVG.

Narrative: AS WE APCHED THE BEGINNING OF THE RWY WE WERE #1 FOR TKOF ON THAT SIDE OF THE RWY. THE ACTIVE RWY WAS RWY 27. WINDS WERE 080 DEGS AT 9 KTS. THERE WAS AN ACFT ON THE OTHER SIDE OF RWY 27 HOLDING BACK ABOUT 75 FT FROM THE HOLD SHORT LINE. ATC THEN TOLD US, OR SO WE ASSUMED, THAT WE WERE CLRED FOR TKOF, TURN R HDG 330 DEGS. WE READ BACK OUR CLRNC AND ENTERED RWY 27 FOR DEP. I WAS BUSY WITH CHKLISTS WHEN MY CAPT HEARD A CONVERSATION WITH THE ACFT ACROSS THE RWY THAT MADE HIM THINK WE ENTERED THE RWY BY MISTAKE. I ASKED FOR CONFIRMATION THAT WE WERE CLRED FOR TKOF AND ATC SAID, 'ARE YOU ON THE RWY?' I REPLIED, 'YES.' HE SAID SOMETHING LIKE, 'OK, YOU ARE CLRED FOR TKOF, TURN R HDG 090 DEGS.' THE WORD OK AND THE NEW HDG OF 090 DEGS INSTEAD OF 330 DEGS MAKES ME BELIEVE WE WERE NOT CLRED ONTO THE RWY AS I AND MY CAPT THOUGHT. DURING TKOF, I HEARD HIM CLR THE ACFT ACROSS THE RWY INTO POS AND HOLD. THE OTHER ACFT WAS FLT Y, WITH SIMILAR ALPHA NUMERIC. EVEN WHEN HE CLRED ACFT #2 ONTO RWY 27, I STILL HEARD OUR CALL SIGN. I BELIEVE THE NON STANDARD PHRASEOLOGY OF, 'OH', THE LETTER INSTEAD OF 'ZERO' THE NUMBER, AND OUR ASSUMPTION WE WERE THE ONLY ONES AROUND WITH A CALL SIGN IN OUR NUMBER RANGE BOTH LED TO THIS POSSIBLE MISTAKE. WE CAN BE MORE ATTENTIVE IN THE FUTURE AND NOT 'ASSUME' ATC WILL TELL US SIMILAR CALL SIGNS ARE ON FREQ AND THE AGE-OLD PROB OF NON STANDARD PHRASEOLOGY COULD PREVENT THIS IN THE FUTURE.

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.