ACR B737 CHARTER FLT TO MIL FIELD WITH TWR NOT OPERATING LANDS WITHOUT PROPER CLRNC AT GTB.

Narrative

ON THE SECOND LEG OF A 3 LEG PART 121 CHARTER TRIP; WE WERE ENRTE TO THE ARMY AIR FIELD AT FT BENNING; GA. I WAS FLYING AND THE CAPT WAS PERFORMING THE PNF DUTIES. ABOUT 100 MI FROM THE FIELD; THE CAPT TUNED THE ATIS. THE INFO INDICATED THAT THE TWR WAS CLOSED AND WOULD NOT OPEN UNTIL XB00. WE WERE APCHING THE FIELD AT APPROX XA00. ARPT ADVISORIES WERE AVAILABLE THOUGH. WE RECEIVED CURRENT WX FROM ZTL. I BRIEFED A VOR APCH TO THE FIELD. ZTL CLRED US FOR THE APCH AND TOLD US TO CONTACT ADVISORY. THE CAPT TUNED THE PUBLISHED ADVISORY FREQ AND ATTEMPTED CONTACT. I DID NOT KNOW IF HE MADE CONTACT OR NOT BECAUSE HE WAS ON THE #2 RADIO. I WAS ON #1 RADIO. THE TWR FREQ WAS TUNED IN #1. BUT TWR WAS CLOSED. WE LANDED UNEVENTFULLY AND DURING TAXI IN; SOMEONE CALLED US ON TWR AND SAID WE NEEDED TO HAVE PERMISSION TO LAND. WE APOLOGIZED AND TAXIED IN. WE AGAIN CHKED THE ATIS AND IT SAID THE TWR WAS CLOSED. EVIDENTLY ARPT ADVISORIES WERE ON TWR FREQ BUT COMMERCIAL CHART DATA ON THE APCH CHARTS HAD A SEPARATE ADVISORY FREQ WHEN THE TWR WAS CLOSED. WE SHOULD NOT HAVE LANDED BECAUSE PART 121 REQUIRES CONTACT; EVEN IF ADVISORY IN NATURE; BEFORE LNDG. SOME FACTORS THAT WERE A FACTOR WERE A NIGHTTIME APCH TO AN UNFAMILIAR ARPT AND THE LATE HRS OF THE CHARTER. I WILL BE MORE VIGILANT TO THIS NEXT TIME.