A300 LNDG JFK PREMATURELY CHANGED FREQ AND MISSED TURN TO FINAL AT 3000 FT DURING PARALLEL APCH PROCS.

Narrative

APCH CTL WAS BUSY WITH 2 PRECEDING ACFT -- A HVY AND A FLT PROVIDING SEPARATION FOR PARALLEL APCHS. WE WERE ON BASE LEG APCHING OUR NORMAL DOGLEG AND SWITCH TO TWR. OUT OF HABIT; THE FO SWITCHED TO TWR FREQ AND PUT JFK GND ON THE OTHER CTL HEAD. I QUESTIONED WHEN WE WERE GOING TO GET A TURN; AND HE SWITCHED BACK TO THE CTL HEAD THAT NOW HAD JFK GND SELECTED. WE RESELECTED APCH AND IMMEDIATELY ESTABLISHED COM. WE WERE GIVEN A TURN BACK TO THE ILS AND CLRED FOR THE APCH. WE WENT THROUGH THE LOC BY ABOUT 2 MI BEFORE THIS TURN BACK. NOTHING OTHER EVENTFUL HAPPENED THROUGHOUT APCH AND LNDG. WE WERE BOTH TIRED AND HABIT PATTERNS WERE FOLLOWED WITHOUT THE NORMAL INPUT FROM APCH CTL. SUPPLEMENTAL INFO FROM ACN 619431: IN A MOMENTARY LAPSE OF REASON; I REACHED DOWN TO PRESET GND FREQ AND MISTAKENLY SET IT IN THE ACTIVE WINDOW; THEREBY INTERRUPTING OUR COM WITH JFK APCH. WE FIGURED OUT THE PROB AND SWITCHED BACK AFTER 1-2 MI; BUT WE DID FLY THROUGH THE ILS COURSE BEFORE RECEIVING OUR CLRNC TO JOIN.