Narrative:

I had just started a 70% benchmark evaluation of a trnee at local control #1. I had been told this trnee was close to recommendation for certification. We had been signed on position for 4 mins when the incursion took place. Local control #1 was busy with 6-8 departures ready to go at various intxns and 2-3 aircraft inbound. The tower was also staffed with a cabin coordinator to assist local controller #1. The trnee had 1 aircraft on left base, 1 aircraft in position and holding at N2, and another ready to depart at N3. Cc had coordinated with ground control and local control #1 to cross runway 7L at west with a veh and at east with 2 small aircraft's. The trnee cleared small aircraft X at N3 for takeoff anticipating the xings to be clear by the time the aircraft took the runway and began his takeoff roll. The trnee thought the second small aircraft Y was clear when in reality it was only the first small aircraft. The veh was never a factor in this incursion. He then went back to the departing small aircraft X and told him 'no delay, cleared for takeoff.' I recognized the fact that small aircraft Y was still crossing the runway and I verbally instructed the trnee to cancel the takeoff clearance due to the crossing small aircraft Y. The trnee promptly complied. Apparently the instrument and student pilot did not hear and/or comprehend the cancelled clearance and questioned the takeoff clearance, but continued to roll. At this point the trnee replied again to cancel takeoff clearance and taxi into position and hold. During this transmission small aircraft X became airborne and the instructor onboard replied 'we're airborne.' small aircraft Y was approximately 3/4 across the runway and downfield approximately 2500' downfield. Being a 70% benchmark evaluation on a trnee who was nearing readiness for certification I felt I had to let the trnee go as long as possible to see if he would correct his error. He did not until I verbally instructed him to do so. This particular trnee has 15 yrs ATC experience (more than I do) and has been previously qualified as an fpl at this facility. I was willing to let this situation develop moreso than I would have done with a less experience trnee. I felt everything that could have been done by the trnee (with my prompting) to correct his error was done. Compliance by the instrument and/or student pilot after the takeoff clearance had been cancelled (which is very clear on tape) could have aided in preventing this runway incursion. One solution for the aircraft pilots to have better heard the first transmission to cancel the takeoff clearance would have been by using headsets instead of speakers. Also they should have been very careful to monitor all xmissions during this critical part of flight, and due to the fact that the tower was very busy with several departures. Better scanning by the local controller would have also prevented this occurrence.

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Original NASA ASRS Text

Title: SMA X HAD LESS THAN STANDARD SEPARATION FROM SMA Y. SYSTEM ERROR. SMA X DEPARTED ON OCCUPIED RWY AFTER TKOF CLRNC WAS CANCELLED. PLT DEVIATION.

Narrative: I HAD JUST STARTED A 70% BENCHMARK EVALUATION OF A TRNEE AT LCL CTL #1. I HAD BEEN TOLD THIS TRNEE WAS CLOSE TO RECOMMENDATION FOR CERTIFICATION. WE HAD BEEN SIGNED ON POS FOR 4 MINS WHEN THE INCURSION TOOK PLACE. LCL CTL #1 WAS BUSY WITH 6-8 DEPS READY TO GO AT VARIOUS INTXNS AND 2-3 ACFT INBND. THE TWR WAS ALSO STAFFED WITH A CABIN COORDINATOR TO ASSIST LCL CTLR #1. THE TRNEE HAD 1 ACFT ON LEFT BASE, 1 ACFT IN POS AND HOLDING AT N2, AND ANOTHER READY TO DEPART AT N3. CC HAD COORDINATED WITH GND CTL AND LCL CTL #1 TO CROSS RWY 7L AT W WITH A VEH AND AT E WITH 2 SMA'S. THE TRNEE CLRED SMA X AT N3 FOR TKOF ANTICIPATING THE XINGS TO BE CLR BY THE TIME THE ACFT TOOK THE RWY AND BEGAN HIS TKOF ROLL. THE TRNEE THOUGHT THE SECOND SMA Y WAS CLR WHEN IN REALITY IT WAS ONLY THE FIRST SMA. THE VEH WAS NEVER A FACTOR IN THIS INCURSION. HE THEN WENT BACK TO THE DEPARTING SMA X AND TOLD HIM 'NO DELAY, CLRED FOR TKOF.' I RECOGNIZED THE FACT THAT SMA Y WAS STILL XING THE RWY AND I VERBALLY INSTRUCTED THE TRNEE TO CANCEL THE TKOF CLRNC DUE TO THE XING SMA Y. THE TRNEE PROMPTLY COMPLIED. APPARENTLY THE INSTR AND STUDENT PLT DID NOT HEAR AND/OR COMPREHEND THE CANCELLED CLRNC AND QUESTIONED THE TKOF CLRNC, BUT CONTINUED TO ROLL. AT THIS POINT THE TRNEE REPLIED AGAIN TO CANCEL TKOF CLRNC AND TAXI INTO POS AND HOLD. DURING THIS XMISSION SMA X BECAME AIRBORNE AND THE INSTRUCTOR ONBOARD REPLIED 'WE'RE AIRBORNE.' SMA Y WAS APPROX 3/4 ACROSS THE RWY AND DOWNFIELD APPROX 2500' DOWNFIELD. BEING A 70% BENCHMARK EVALUATION ON A TRNEE WHO WAS NEARING READINESS FOR CERTIFICATION I FELT I HAD TO LET THE TRNEE GO AS LONG AS POSSIBLE TO SEE IF HE WOULD CORRECT HIS ERROR. HE DID NOT UNTIL I VERBALLY INSTRUCTED HIM TO DO SO. THIS PARTICULAR TRNEE HAS 15 YRS ATC EXPERIENCE (MORE THAN I DO) AND HAS BEEN PREVIOUSLY QUALIFIED AS AN FPL AT THIS FAC. I WAS WILLING TO LET THIS SITUATION DEVELOP MORESO THAN I WOULD HAVE DONE WITH A LESS EXPERIENCE TRNEE. I FELT EVERYTHING THAT COULD HAVE BEEN DONE BY THE TRNEE (WITH MY PROMPTING) TO CORRECT HIS ERROR WAS DONE. COMPLIANCE BY THE INSTR AND/OR STUDENT PLT AFTER THE TKOF CLRNC HAD BEEN CANCELLED (WHICH IS VERY CLR ON TAPE) COULD HAVE AIDED IN PREVENTING THIS RWY INCURSION. ONE SOLUTION FOR THE ACFT PLTS TO HAVE BETTER HEARD THE FIRST XMISSION TO CANCEL THE TKOF CLRNC WOULD HAVE BEEN BY USING HEADSETS INSTEAD OF SPEAKERS. ALSO THEY SHOULD HAVE BEEN VERY CAREFUL TO MONITOR ALL XMISSIONS DURING THIS CRITICAL PART OF FLT, AND DUE TO THE FACT THAT THE TWR WAS VERY BUSY WITH SEVERAL DEPS. BETTER SCANNING BY THE LCL CTLR WOULD HAVE ALSO PREVENTED THIS OCCURRENCE.

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.