A310-200. THE ATCT TWR SUPVR QUESTIONS WHETHER THE CREW OBSERVED THE CLOSED RWY.

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CLRED TO LAND BGR WITH FIRST 3500 FT CLOSED OF RWY 15. WE HAD A PLAN; EXECUTED IT AND WERE HAPPY; BUT THE TWR WASN'T. I OPERATED AS THE CAPT FROM ZZZZ TO BANGOR; ME. PRIOR TO THE DEP NOTAMS FOR BANGOR SAID 'RWY CLOSED 15/33 NW 3500 FT.' ALSO NOTAMED OUT WERE ILS RWY 15 GS AND DME; AND RWY 15 PAPI. FO WAS PF. WE HAD HRS TO CONSIDER RWY 15. WE ALSO RECEIVED ATIS WITH SAME RWY CLOSURE INFO AND RPTING 10 MI VISIBILITY; CLR OF CLOUDS BELOW 12000 FT; AND GS AND DME FOR ILS 15 UNRELIABLE. WE REVIEWED APCHS AND SELECTED VOR/DME 15 BECAUSE OF ITS NAVAIDS WERE FUNCTIONING AND IT WOULD PROVIDE US WITH AN AID FOR VERT NAV BY GUIDING US TO A CERTAIN KNOWN POINT (MDA AND VDP) TO BEGIN OUR FINAL DSCNT TO THE DISPLACED LNDG AREA. THE MDA FOR VOR DME 15 IS 368 FT ABOVE TOUCHDOWN ELEVATION. FO COMPUTED A NORMAL VDP AT .7 DME PAST THE VOR. HE THEN ADDED .5 MI TO SLIDE THE NORMAL VDP TOWARD THE RWY TO COMPENSATE FOR THE DISPLACED THRESHOLD. I REPEATED THE VDP CALCULATIONS AND ARRIVED AT THE SAME NUMBERS. WE ALSO PLANNED TO USE THE PRECISION INST RWY MARKINGS TO AID IN DETERMINING 3500 FT. PAGE 156 OF COMMERCIAL CHART INTRO SHOWS THE LAST SET OF SINGLE BAR MARKINGS EXTENDING FROM 3000 FT TO 3075 FT. DURING VECTORS TO THE RWY; WE WERE ADVISED AND CONFIRMED BACK 3500 FT RWY CLOSURE. AT ABOUT 8 MI ON FINAL; I CALLED 'FIELD IN SIGHT' AND WAS CLRED VISUAL APCH. SOON TO FOLLOW WE WERE 'CLRED TO LAND; FIRST 3500 FT CLOSED.' WE CONTINUED TO FLY THE BRIEFED VOR/DME 15 PROFILE. AT THE ADJUSTED VDP OF 1.2 DME AND ON MDA AND ON AIRSPD; THE PF ANNOUNCED 'LEAVING MDA' AND BEGAN A NORMAL DSCNT. I SCANNED THE RWY FOR ACFT OR EQUIP. THE ENTIRE RWY WAS CLR AND HAD NO DISPLACED THRESHOLD MARKINGS OR SIGNAGE OF ANY KIND. I CONTINUED TO STUDY THE RWY FOR MARKINGS. I SAW THE PRECISION INST RWY MARKINGS THAT WE WERE FLYING OVER. I DID ALSO SEE THE '8' DISTANCE REMAINING SIGN GO BY US PRIOR TO TOUCHDOWN. THIS I TOOK AS CONFIRMATION OF CORRECT DISTANCE DOWN THE RWY. 11500 FT LENGTH RWY MINUS 8000 REMAINING = 3500 FT BEHIND US. WE WERE AWARE OF THIS 8000 FT REMAINING VALUE; BECAUSE WE HAD ADDRESSED IT IN THE SHORTENED RWY COMPUTATIONS (PRECISE NUMBERS ARE 11440 FT MINUS 8000 FT = 3440 FT). I REMEMBER FLYING BEYOND THE LAST OF THE PRECISION INST RWY MARKINGS. LNDG WAS NORMAL AND WE TAXIED TO THE RAMP AND SHUT DOWN. WHILE CHKING INTO OPS; I RECEIVED A CALL FROM TWR SAYING THEY WERE CONCERNED ABOUT OUR TOUCHDOWN POINT. AT THE TWR MAN'S REQUEST; I PROVIDED HIM WITH MY NAME AND CERTIFICATE NUMBER. LATER I LEARNED FROM A LCL PIPER PLT THAT THERE ARE WHITE LATTICE PANELS IN THE GRASS OFF TO THE SIDES OF THE RWY. I CANNOT SAY WHERE WE TOUCHED DOWN IN RELATION TO THESE PANELS BECAUSE WE NEVER SAW THEM. I HAVE NEVER SEEN OR HEARD OF WHITE LATTICE PANELS BEING USED TO MARK ANYTHING AT AN ARPT; CERTAINLY NOT AS THE SOLE SIGNAGE IDENTING A DISPLACED THRESHOLD. THE AIM TELLS ME THAT A DISPLACED THRESHOLD IS MARKED WITH A WIDE WHITE BAR ACROSS THE WIDTH OF THE RWY. MY MEMORY SAYS THAT I HAVE ALWAYS SEEN A LARGE WHITE BAR IDENTING A DISPLACED THRESHOLD AND IN AT LEAST ONE CASE THE WHITE BAR WAS SUPPLEMENTED WITH FLASHING STROBES. IF BANGOR INTENDED LATTICE PANELS AS THE SOLE MARKERS; THEN THAT INFO TO ME WOULD HAVE BEEN HELPFUL TO US. SELF CRITIQUE: WE IDENTED A RISK -- THE LACK OF VERT GUIDANCE TO RWY 15. WE ADDRESSED THAT RISK BY POSITIONING OURSELVES AT THE KNOWN MDA AND AT THE 1.2 DME POINT IN SPACE. THEN WE FLEW A NORMAL DSCNT PAST THE KNOWN POINT PRECISION INST MARKINGS AND HAPPENED TO NOTE A PASSING '8' REMAINING BOARD JUST AT TOUCHDOWN. IF I'D KNOWN THE RWY HAD NO WHITE THRESHOLD BAR AND KNOWN TO LOOK 'OUTBOARD' THE RWY FOR ONLY LATTICE PANELS; THAT WOULD HAVE SIMPLIFIED OUR 'WHERE TO AIM' PROB. I DIDN'T KNOW TO LOOK OUTBOARD FOR LATTICE PANELS. WE HAD A PLAN TO ADDRESS VERT DSCNT AND DOWN RWY POSITIONING. WE EXECUTED THAT PLAN; AND WE BOTH BELIEVED THAT WE HAD ME THE HURDLE OF A STABILIZED APCH TO A POINT 3500+ FT DOWN THE RWY -- ONLY THE TWR'S CALLS PUT ME IN DOUBT. SUPPLEMENTALINFO FROM ACN 624115: LNDG AT BANGOR ARPT. WAS AWARE OF BGR NOTAM 'RWY CLOSED 15/33 NW 3500 FT EXC 15 MIN PPR.' NOTAM DID NOT ADDRESS ANY DESCRIPTION OF DISPLACED THRESHOLD MARKINGS OR VISUAL CUES DELINEATING CLOSED PORTION OF RWY. SINCE ILS GS INFO AND PAPI INFO TO RWY 15 WERE UNRELIABLE DUE TO CLOSED PORTION OF RWY; PLANNED AND BRIEFED TO FLY THE VOR/DME APCH TO RWY 15 AS AN AID FOR VERT NAV. COMPUTED A VISUAL DSCNT POINT OF .7 DME PAST VOR FOR NORMAL APCH AND ADDED .5 DME (3000 FT) TOTALING 1.2 DME FOR AN ADJUSTED VDP IN ORDER TO LAND LONG. BEGAN DSCNT OUT OF MDA (560 FT MSL; 368 FT AGL) AT 1.2 DME AND MAINTAINED A NORMAL 3 DEG DSCNT ATE LOOKING AT RWY. NOTICING NO DISPLACED THRESHOLD MARKINGS OR SIGNAGE OF ANY KIND DENOTING CLOSED PORTION OF RWY; A VISUAL AIM POINT WAS ESTABLISHED AT LAST SINGLE BAR OF RWY TOUCHDOWN ZONE MARKING WHICH SHOULD EQUATE TO 3000 FT FROM THRESHOLD. AFTER FLARE WAS INITIATED; PLANNED ON FLOATING AT LEAST 500 FT BEYOND TOUCHDOWN ZONE MARKING AIM POINT AND LNDG BEYOND 3500 FT FROM NORMAL THRESHOLD. TOUCHDOWN AND TAXI WERE NORMAL. AFTER SHUTDOWN; BANGOR FLT OPS INFORMED CAPT TO CONTACT TWR ABOUT A POSSIBLE LNDG EVENT. AT NO TIME DID WE SEE PERSONNEL OR VEHICLES ON ANY PART OF THE CREW OR CLOSED LNDG RWY SURFACE WHICH OUR ACFT MIGHT HAVE ENDANGERED.