Narrative:

Our aircraft (#1) was cleared to taxi into position and hold. We were then cleared for takeoff and assigned fly runway heading. We began our takeoff roll from departure end. Aircraft #2 was holding in position at taxiway B and was cleared to taxi into position and hold after clearing aircraft #1 for takeoff. Aircraft #2 taxied onto runway 11 during our takeoff roll. We aborted our takeoff and was able to get the aircraft. Stopped without colliding with aircraft #2. Our opinion of the cause of the incident was the failure of ATC to positively identify the position of aircraft #2 and subsequently clearing aircraft #2 onto the runway at the same time aircraft #1 was cleared for takeoff. Callback conversation with reporter revealed the following information: reporter called the tower and was advised that the controller forgot to verify the actual position of the cessna prior to clearing him onto the runway. The reporter advised he had to brake very hard. Following the training flight, the aircraft was inspected and two of the three tires had to be replaced, specifically attributed to this event.

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Original NASA ASRS Text

Title: C172 REJECTS TKOF A CAE LCL CLRS ANOTHER ACFT INTO POSITION AND HOLD IN FRONT OF DEPING CESSNA.

Narrative: OUR ACFT (#1) WAS CLRED TO TAXI INTO POSITION AND HOLD. WE WERE THEN CLRED FOR TAKEOFF AND ASSIGNED FLY RWY HDG. WE BEGAN OUR TKOF ROLL FROM DEP END. ACFT #2 WAS HOLDING IN POSITION AT TXWY B AND WAS CLRED TO TAXI INTO POSITION AND HOLD AFTER CLRING ACFT #1 FOR TAKEOFF. ACFT #2 TAXIED ONTO RWY 11 DURING OUR TKOF ROLL. WE ABORTED OUR TKOF AND WAS ABLE TO GET THE ACFT. STOPPED WITHOUT COLLIDING WITH ACFT #2. OUR OPINION OF THE CAUSE OF THE INCIDENT WAS THE FAILURE OF ATC TO POSITIVELY IDENTIFY THE POSITION OF ACFT #2 AND SUBSEQUENTLY CLRING ACFT #2 ONTO THE RWY AT THE SAME TIME ACFT #1 WAS CLRED FOR TKOF. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR CALLED THE TWR AND WAS ADVISED THAT THE CTLR FORGOT TO VERIFY THE ACTUAL POSITION OF THE CESSNA PRIOR TO CLRING HIM ONTO THE RWY. THE RPTR ADVISED HE HAD TO BRAKE VERY HARD. FOLLOWING THE TRNG FLT, THE ACFT WAS INSPECTED AND TWO OF THE THREE TIRES HAD TO BE REPLACED, SPECIFICALLY ATTRIBUTED TO THIS EVENT.

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.