AN INITIAL PLTDEV DETERMINATION WAS CHANGED TO AN OPERROR AT PHL WHEN TKOF WAS ABORTED BY CTLR BECAUSE OF POSSIBLE RWY INCURSION BY TAXIING ACFT; AMASS ALERTED.

Narrative

INITIALLY; THE EVENT WAS DETERMINED TO BE A PLTDEV AT THE FACILITY LEVEL. WASHINGTON HEADQUARTERS DETERMINED THE EVENT TO BE CTLR ERROR. ACFT X; AN LR25; LANDED RWY 9R. THE CTLR INSTRUCTED ACFT X TO HOLD SHORT RWY 9L AT TXWY M. ACFT X READ BACK 'RWY 9L; TXWY M.' THE CTLR CLRED ACR Y; A B757; FOR TKOF RWY 9L. THE CTLR OBSERVED ACFT X TAXIING AT A STANDARD RATE. IT APPEARED TO THE CTLR; THAT ACFT X WAS NOT GOING TO COMPLY WITH THE HOLD SHORT INSTRUCTIONS. THE CTLR AGAIN ISSUED HOLD SHORT INSTRUCTIONS TO ACFT X AT RWY 9L; TXWY M. THE CTLR CANCELED TKOF CLRNC FOR ACR Y FOR WHICH ACR Y ACKNOWLEDGES. ACFT X ADVISES THE CTLR HE IS NOT ON THE RWY. APPROX 20 SECONDS AFTER THE TKOF CLRNC WAS CANCELED FOR ACR Y. THE AMASS ALERTS; ACFT X IS NOT ON THE RWY; HOWEVER; THE ACFT IS PAST THE HOLD LINE. ACR Y EXITS RWY 9L AT TXWY N; UPFIELD OF ACFT X; AND SHORT OF TXWY M. WASHINGTON HEADQUARTERS INTERP/EXPLANATION FOR CTLR ERROR IS DUE TO THE PLT OF ACFT X; NOT READING BACK THE HOLD SHORT INSTRUCTIONS VERBATIM AND THE CTLR NOT CATCHING THE READBACK.