C172 TRAINING FLT VEERS OFF THE TXWY DURING AN ATTEMPTED 45 DEG TURN ONTO TXWY A AT MYF; CA.

Narrative

PREFLT AND START-UP WERE COMPLETED AS NORMAL. AS TAXI WAS STARTED; I TESTED THE L AND R RUDDER PEDALS; THEN THE BRAKES. THE STUDENT THEN DID THE SAME. ONCE REACHING THE INTXN OF TXWY I AND TXWY G; THE STUDENT RECEIVED A TAXI CLRNC TO RWY 28R VIA TXWY H AND TXWY A. WE PROCEEDED TO TAXI AND WHEN THE STUDENT MADE THE R-HAND TURN FROM TXWY G AND TXWY H; I REALIZED OUR TAXI SPD WAS HIGH. I TOLD THE STUDENT TO REDUCE PWR AND SLOW DOWN. THE STUDENT DID AS INSTRUCTED AND WE CONTINUED E ON TXWY H. UPON REACHING THE INTXN OF TXWY H AND TXWY A; THE STUDENT APPLIED L RUDDER AND THE ACFT CONTINUED STRAIGHT AHEAD. I REACTED BY PULLING THE REMAINING PWR AND APPLYING HVY BRAKING. THE ACFT WAS UNABLE TO BE STOPPED ON THE TXWY AND DID NOT COME TO A COMPLETE STOP UNTIL IN THE DIRT AT THE E END OF THE TXWY. I FEEL THAT THE INCIDENT COULD HAVE BEEN AVOIDED HAD I; THE INSTRUCTOR; HAD THE STUDENT REDUCE PWR TO IDLE BEFORE THE TURN; AND ALSO SLOWED THE TAXI SPD. THE ACFT MAY NOT HAVE REACTED TO THE CTL INPUT AS QUICKLY AS EXPECTED; BUT AFTER TESTING THE CTLS ONCE BACK ON THE TXWY; I WAS UNABLE TO FIND ANY FAULT DUE TO ACFT SYS MALFUNCTION. THIS INCIDENT OCCURRED AT MYF; SAN DIEGO; CA.