PLT RECEIVES A LOW ALT WHILE CONDUCTING A NON PRECISION APCH.

Narrative

I WAS ON AN ILS RWY 6 APCH INTO ISP. I HAD A FRIEND ALONG FOR THE FLT WHO IS A CFI AIM ALSO. WHILE ON THE APCH THE TWR CALLED AN ALT ALERT AND STATED LCL ALTIMETER SETTING. A LITTLE MORE THAN A MIN WAS LEFT TO GO ON THE APCH. THE PLT IN THE OTHER SEAT WHO WAS 'WORKING' THE RADIOS CAUGHT SIGHT OF THE APCHING LIGHTS. I LOOKED UP TO VERIFY THIS AND ALSO CAUGHT SIGHT OF THE APCH LIGHTS. I THEN DSNDED FROM ABOUT 500 FT MSL TO A LITTLE BELOW LOC MDA (420 FT) TO KEEP THE LIGHTS IN SIGHT. I STAYED AT THE ALT FOR ABOUT 5-10 SECONDS. THE TWR THEN CALLED AN ALT ALERT. HAVING NEVER HEARD THAT TERM BEFORE ON AN APCH I WAS A LITTLE STARTLED AND CLB BACK ABOVE MDA AND LOST SIGHT OF THE LIGHTS. KNOWING I WOULD SEE THE APCH LIGHTS AGAIN IN A FEW SECONDS (CEILING WAS RAGGED) I MAINTAINED ALT AND COURSE. WHEN I HAD THE APCH LIGHTS IN SIGHT AGAIN; I TOLD THE OTHER PLT TO TELL THE CTLR WE HAD THE ARPT IN SIGHT. WE WERE CLRED TO LAND AND MADE A NORMAL APCH AND LNDG. THE MAIN CONTRIBUTING FACTOR FOR RECEIVING AN ALT ALERT WAS NOT CALLING THE ARPT IN SIGHT THE FIRST TIME TO THE CTLR. THE CEILING WAS RAGGED WHICH ACCOUNTED FOR SIGHTING THE ARPT THE FIRST TIME AND THEN LOSING SIGHT OF THE ARPT FOR A FEW SECONDS WHEN I CLBED ALSO; WHEN I BROKE OUT THE FIRST TIME; I DID NOT WANT TO LOSE SIGHT OF THE ARPT; SO I MAY HAVE DSNDED BELOW AN MDA ALT THAT MAY HAVE MADE THE CTLR A LITTLE UNCOMFORTABLE. A LITTLE LIGHT CHOP WAS ALSO ENCOUNTERED ON THE APCH. A LOT OF CONCENTRATION IS NEEDED WHEN ON AN APCH TO NEAR MINS. ONCE THE ARPT IS IN SIGHT; HUMAN TENDENCY IS TO RELAX A LITTLE AND 'BRING IT HOME.' CONCENTRATION AND AWARENESS OF ALL INVOLVED MUST BE KEPT UNTIL THE ACFT IS PARKED AND TIED DOWN. NEVER ASSUME SOMEONE ELSE KNOWS WHAT YOU SEE OR DON'T SEE.