INSTRUCTOR WITH INST STUDENT CROSSES HOLD LINE WHEN INSTRUCTED TO HOLD SHORT.

Narrative

WHILE WAITING FOR CLRNC TO DEPART RWY 2R AT PDK; THE CTLR CLRED US (MY INST STUDENT AND ME) TO HOLD SHORT RWY 2R. BECAUSE OF THE VOLUME OF TFC WAITING TO DEPART (7 ACFT) AND LAND; MY STUDENT MISTOOK THE INSTRUCTIONS FOR 'TAXI INTO POS AND HOLD 2R.' AS A RESULT; PWR WAS GIVEN AND THE AIRPLANE ROLLED PAST THE HOLD LINE; BUT WELL SHORT OF THE ACTIVE RWY. I APPLIED BRAKES AND HELD THE AIRPLANE IN POS UNTIL CLRNC WAS GIVEN TO DEPART. THE SITUATION WAS CAUSED PRIMARILY BY THE VERY HECTIC ATMOSPHERE AT PDK AT THE TIME. TFC WAS VERY HVY. FROM THE TIME OF OUR START UP TO OUR DEP; OVER 1 HR HAD ELAPSED. THE CTLR WAS VERY COMPETENT IN HANDLING TFC; BUT AS A PLT; I HAD TO PAY STRICT ATTN TO THE CTLR SO I COULD RECEIVE ALL CLRNCS AND COM. THE ARPT VOLUME WAS NEW TO MY STUDENT; THEREFORE; I HANDLED THE RADIO AND RELAYED THE INSTRUCTION TO HIM. AT THE TIME OF THE INCIDENT THE CTLR DID CLR US TO HOLD SHORT; TO WHICH I REPLIED 'IDENT; HOLDING SHORT 2R.' AFTER WE CROSSED THE LINE; THE CTLR NEVER QUESTIONED OUR INTENTIONS; BUT I CALLED BACK FOR CONFIRMATION OF THE 'HOLD SHORT' INSTRUCTIONS AND WAS INDEED INSTRUCTED TO HOLD SHORT. NO FURTHER COMPLICATIONS AROSE; BUT A POTENTIAL DEADLY SCENARIO COULD HAVE TRANSPIRED WITH LNDG TFC. THE PROBLEM WAS NOT ARPT MARKINGS; BUT COM BTWN MY STUDENT; THE TWR; AND MYSELF. AFTER THE FLT; I QUESTIONED MY STUDENT ABOUT WHAT HE PERCEIVED THE PROBLEM TO BE. HE TOLD ME HE HEARD THE CTLR CLR THEM TO TAXI INTO POS. I REEMPHASIZED THE CARE AND IMPORTANCE OF LISTENING; WAITING DOWN; AND REPEATING INSTRUCTIONS.