HDG TRACK DEV IN A NIGHT OP.

Narrative

HOW THE PROB AROSE. I PREPARED FOR THE ILS RWY 7 APCH. I SET UP THE KNS 81 FOR ILS IN BIN 0 AND GAVIOTTA VOR (GVO) IN BIN 1 GPS HAD HABUT; NAPPS; SBA AS WAYPOINTS DISPLAYED ON EFIS. I TUNED IN ILS; LISTENED TO MORSE CODE 'ISBA' - GOT READY FOR ILS. APCH SAID BECAUSE OF OTHER TFC; I WOULD HAVE TO FLY VOR 25; CIRCLE FOR RWY 15 (I'M NOT SURE NOW IF IT WAS RWY 15). I RESET KNS 81 TO BIN 1 AND PRESSED THE 'USE' BUTTON AND GOT READY FOR VOR 25. I CROSSED ILS HDG ABOUT SE. APCH SAID I COULD HAVE ILS 7 AFTER ALL AND GAVE ME A VECTOR TO ILS. I SELECTED BIN 0 (KNS 81 DISPLAYED 0) BUT; IN THE CONFUSION; I DID NOT PRESS 'USE.' THEN THE KNS 81 DISPLAYED DATA FOR ILS BUT WAS SET TO GVO VOR!. I PUNCHED APCH ON AUTOPLT AND INITIAL ACTION SEEMED APPROPRIATE. I WAS VERY BUSY IN COCKPIT WHEN APCH CALLED 'YOU ARE N OF LOC' I NOTICED HDG HAD SLOWED TO N AND WAS JUST SORTING THINGS OUT WHEN APCH GAVE ME AN IMMEDIATE VECTOR TO S. CLOSE ATTN AND PROMPT ACTION BY APCH WAS GREATLY APPRECIATED. HOWEVER THE DESIGN OF THE ANCIENT KNS 81 THAT WILL DISPLAY THE ILS (WHILE BLINKING A LIGHT) WHILE NAVIGATING TO THE VOR CAN BE A SAFETY HAZARD. THE FACT THAT I HAD ONCE VERIFIED ILS BY CODE CONTRIBUTED TO THE FACT THAT I DID NOT VERIFY BY CODE THE SECOND TIME -- I HAD ALREADY DONE IT -- OR SO I THOUGHT.