A B737-700 PIC'S RPT REGARDING THE AUTO SHUT DOWN OF VASI REFERENCE DURING A LOCALIZER ONLY APCH TO RWY 30 L AT DUSK AT SJC; CA.

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APCH TO SJC 30 L AT DUSK WITH HAZE SUN IN YOUR EYES GS NOTAMMED OUT ILS RWY 30 L. FLYING LOC ONLY PICKED UP VASIS AND WERE TRACKING VASI FOR GS GUIDANCE. YOU COULD SEE THE VASI 2.3 MI BEFORE RWY CAME INTO VIEW. BTWN 4-5 MI FROM RWY VASI'S WENT OUT. ASKED TWER IF THEY TURNED THEM OFF; RESPONSE WAS VASI'S ARE HOOKED UP TO PHOTOELECTRIC CELL THAT TURNS THEM OFF AS IT GETS DARK AND THEY CAN'T TURN THEM BACK ON. VERY DISCONCERTING TO LOSE VASI'S ON APCH IN THIS SIT. RECOMMENDATION; VASI'S SHOULD BE TWR CTLED AT ALL TIMES REGARDLESS OF TIME OF DAY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE PIC RPTR STATED THAT HE CREW HAD THE PAPI LIGHTS IN SIGHT. THOSE ARE THE LIGHTS TO THE LEFT OF RWY 30L. IT SEEMS THAT AT DUSK THE LIGHTS GO OUT AS CONTROLLED BY THE PHOTO-ELECTRIC CELL BUT ARE READABLE LATER AT NIGHT. THE PIC MADE ANOTHER FLT INTO SJC AT DUSK AND THE SAME THING OCCURRED TO HIS FLT; THE LIGHTS WENT OUT. HE MAINTAINS THAT THE LIGHT CELL IS CONTROLLED BY THE CITY; NOT THE FAA.