ACR ON ILS VECTOR TO BHB SWITCHED TO CTAF AND ANNOUNCED OM AND REQUESTED ANY TFC TO ADVISE. TFC WAITING ON THE GND WAS TOLD TO HOLD FOR RELEASE. WHEN THE ACR WAS AT 200 FT THE TFC ON THE GND RPTED THEY WERE ON THE RWY IN POS AND ASKED IF THERE WAS ANY TFC ON THE ILS.

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WE WERE BEING VECTORED BY BANGOR APCH FOR THE ILS RWY 22. A BONANZA ON THE GND AT BHB REQUESTED IFR RELEASE FROM BGR APCH. BGR SAID 'HOLD FOR RELEASE.' BGR VECTORED US ONTO THE LOC AND CLRED US FOR THE APCH. ABOUT 2 MI FROM THE OM; BGR SWITCHED US OVER TO THE CTAF. WE SWITCHED OVER AND ANNOUNCED THAT WE WERE AT THE OM FOR THE ILS RWY 22 AT BHB AND REQUESTED ANY TFC AT BHB TO ADVISE. WE RECEIVED NO RESPONSE. THE APCH WAS ROUTINE UNTIL APPROX 200 FT ABOVE DECISION HT. AT THAT TIME WE HEARD 'IS ANYONE ON THE ILS?' WE ADVISED WE WERE ON SHORT FINAL. THE OTHER ACFT ADVISED HE WAS A BONANZA IN TKOF POS RWY 22 AWAITING IFR RELEASE FROM BGR. BY THEN; WE HAD BROKEN OUT OF THE CLOUDS AND VISUALLY CONFIRMED THAT AN ACFT WAS ON THE RWY. WE EXECUTED THE PUBLISHED MISSED APCH. AFTER RECONTACTING BGR APCH; I ASKED BGR TO RELEASE THE BONANZA TO AVOID A POSSIBLE RECURRENCE. THE AIRFIELD IS UNCTLED AND IT'S UNCLR IF THE BONANZA KNEW HE WAS BEING HELD FOR AN INBOUND ACFT. WE WILL BE MAKING ADDITIONAL CTAF XMISSIONS TO INCREASE CHANCES OF ACFT ON GND HEARING US.