A CL600 TRAINING FLT GETS INVOLVED IN IMC FLT IN VFR DURING A CLOSING OF THE LCL TWR AND APCH CTL FACILITY AT GSP; SC.

Narrative

THIS WAS AN ACFT FAMILIARIZATION FLT AFTER SIMULATOR TRAINING. I WAS LULLED INTO A FALSE SENSE OF SECURITY BY THE CHK AIRMAN IN REGARDS TO THE AIRSPACE/WX REQUIREMENTS. THE PIC (CHK AIRMAN) PICKED UP OUR LCL IFR CLRNC FOR OUR TRAINING FLT. ON OUR THIRD TKOF THE TWR AND APCH CTL WERE IN THE PROCESS OF CLOSING DOWN FOR THE NIGHT AND HANDING THE AIRSPACE OVER TO ZTL. THE PIC CALLED FOR AND RECEIVED TKOF CLRNC FROM THE TWR. ONCE AIRBORNE; PIC CALLED ZTL AND THEY WERE UNAWARE OF US AND OUR IFR STATUS. WE WERE TOLD TO MAINTAIN VFR; WE WERE STILL IN SURFACE LEVEL CLASS C/E AIRSPACE WITH LESS THAN 3 MI OF GND VISIBILITY. I SLOWED THE ACFT TO MINIMUM MANEUVERING SPD AND PUT A PLAN TOGETHER TO KEEP THE ACFT SAFE IN THE DARK LIMITED VISIBILITY NIGHTTIME VFR SIT. WE NEVER STATED 'CANCEL MY IFR.' THE PIC WAS HANDLING THE RADIOS; BUT I THINK A CALL BACK TO GREER WOULD HAVE CLRED UP THE CONFUSION THAT WE WERE ON AN IFR CLRNC. I WOULD HAVE BEEN MORE INSISTENT ABOUT OUR IFR CLRNC; THUS PREVENTING US FROM THE DANGERS OF NIGHTTIME LIMITED VISIBILITY VFR. AFTER THE INBOUND TFC WAS CLR; WE WERE GIVEN OUR IFR CLRNC. ON A 4 MI FINAL; THE PIC CANCELED OUR IFR. I DO NOT THINK HE REALIZED THAT NWS STILL RPTS THE WX AND THEY SAID THE GND VISIBILITY WAS LESS THAN 3 MI. THE AIRSPACE WAS THEN SURFACE BASED; CLASS E; WHICH REQUIRES AN IFR CLRNC FOR THESE CONDITIONS. BECAUSE IT WAS MY FIRST FLT IN THE ACFT; IT WAS VERY DIFFICULT TO BE ASSERTIVE EXCEPT WHEN SAFETY WAS AN ISSUE DURING OUR VFR ONLY SIT. I HAD TO LET THE NON SAFETY AIRSPACE ISSUES SLIDE; NOT FILING A COMPLETE GND BASED FLT PLAN COULD HAVE CONTRIBUTED.