CHARTER SMT UNAUTH RWY CROSSING CAUSES TKOF ABORT.

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SALISBURY ARPT IS A NON TWR ARPT. ADVISORY INFO IS HANDLED THROUGH THE FSS LOCATED ON THE FIELD. HOWEVER; IFR CLRNCS ARE OBTAINED THROUGH PATUXENT RIVER APCH WHICH IS REMOTED ON THE FIELD. AFTER ENG START WE OBTAINED RWY IN USE INFO FROM SBY FSS AND WERE ADVISED TO OBTAIN OUR IFR CLRNC FROM PATUXENT ON A DIFFERENT FREQ. OUR TAXI RTE REQUIRED OUR XING THE RWY IN USE AND DURING THIS TIME WE WERE OBTAINING OUR IFR CLRNC ON A FREQ DIFFERENT FROM THE ADVISORY FREQ. NEARING THE POINT WE WOULD CROSS THE RWY IN USE THE SIC (FLYING AS PIC) ASKED 'HOW DOES IT LOOK ON THAT SIDE?' I SCANNED THE SKY ON THE APCH TO THE RWY IN USE AND RPTED IT AS ALL CLR. LOOKING TO THE SAME AREA AS WE CROSSED THE RWY I NOTICED AN SMT ABORTING HIS TKOF ABOUT 100 YARDS FROM US. THE PLT MUST HAVE BEEN FURIOUS AT US. AFTER SWITCHING BACK TO THE FSS FREQ THEY HAD SOME STRONG ADVICE FOR US. WE CERTAINLY DESERVED IT. OUR WHEELS SHOULD NEVER HAVE MOVED WHILE WE WERE OFF THE ADVISORY FREQ. WE WOULD CERTAINLY HAVE HEARD THE PLT OF THE SMT ADVISING TFC OF HIS DEP.