Narrative:

At the end of an instruction night with a multi-engine student we returned to dpa airport and landed on runway 10. We decided to taxi back for 1 more takeoff and landing. Traffic was using both runways 15 and 10. An small aircraft was given a clearance to taxi into position and hold runway 15 and, at the same time, my student and I were also given a clearance to taxi into position and hold runway 10. Immediately following, there was a series of clrncs given at the same time which is where our confusion began. The small aircraft in position on runway 15 was 'cleared for takeoff no delay' immediately followed by a clearance for another small aircraft Z waiting at runway 15 to 'taxi into position and hold for traffic departing runway 10.' my student, believing the takeoff clearance was intended for him, began to roll. I didn't question his decision after 'traffic departing runway 10.' my student recalls answering the takeoff clearance with our call sign 'aircraft X.' as we began to rotate, I noticed the small aircraft traffic approximately 200 ft AGL crossing the departure end of runway 10. No evasive action was necessary, and we were never closer than approximately 1500 ft from the departing small aircraft traffic, but the result was less than standard separation. I believe this incident was caused by the confusion in the series of clearance and the speed they were given. This could have been prevented by a full readback in clearance rather than just our call sign.

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Original NASA ASRS Text

Title: UNAUTH TKOF CREATES A POTENTIAL CONFLICT WITH ANOTHER DEPARTING ACFT.

Narrative: AT THE END OF AN INSTRUCTION NIGHT WITH A MULTI-ENG STUDENT WE RETURNED TO DPA ARPT AND LANDED ON RWY 10. WE DECIDED TO TAXI BACK FOR 1 MORE TKOF AND LNDG. TFC WAS USING BOTH RWYS 15 AND 10. AN SMA WAS GIVEN A CLRNC TO TAXI INTO POS AND HOLD RWY 15 AND, AT THE SAME TIME, MY STUDENT AND I WERE ALSO GIVEN A CLRNC TO TAXI INTO POS AND HOLD RWY 10. IMMEDIATELY FOLLOWING, THERE WAS A SERIES OF CLRNCS GIVEN AT THE SAME TIME WHICH IS WHERE OUR CONFUSION BEGAN. THE SMA IN POS ON RWY 15 WAS 'CLRED FOR TKOF NO DELAY' IMMEDIATELY FOLLOWED BY A CLRNC FOR ANOTHER SMA Z WAITING AT RWY 15 TO 'TAXI INTO POS AND HOLD FOR TFC DEPARTING RWY 10.' MY STUDENT, BELIEVING THE TKOF CLRNC WAS INTENDED FOR HIM, BEGAN TO ROLL. I DIDN'T QUESTION HIS DECISION AFTER 'TFC DEPARTING RWY 10.' MY STUDENT RECALLS ANSWERING THE TKOF CLRNC WITH OUR CALL SIGN 'ACFT X.' AS WE BEGAN TO ROTATE, I NOTICED THE SMA TFC APPROX 200 FT AGL XING THE DEP END OF RWY 10. NO EVASIVE ACTION WAS NECESSARY, AND WE WERE NEVER CLOSER THAN APPROX 1500 FT FROM THE DEPARTING SMA TFC, BUT THE RESULT WAS LTSS. I BELIEVE THIS INCIDENT WAS CAUSED BY THE CONFUSION IN THE SERIES OF CLRNC AND THE SPD THEY WERE GIVEN. THIS COULD HAVE BEEN PREVENTED BY A FULL READBACK IN CLRNC RATHER THAN JUST OUR 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.