SMA PLT FAILS TO CLOSE IFR FLT PLAN WITH CTLR AT CTR.

Narrative

WHEN I RECEIVED MY CLRNC FOR THE VOR 35 APCH INTO BEATRICE; ZMP INCLUDED THE NORMAL 'CLOSE WITH RADIO UPON LNDG;' WHICH I ACKNOWLEDGED. WHILE CONDUCTING THE PROC TURN;. ANOTHER ACFT CALLED CTR REQUESTING THEIR IFR CLRNC OUT OF BEATRICE. THEY HAD DEPARTED VFR SBOUND AND WANTED THEIR CLRNC PRIOR TO CLBING THROUGH THE LOW CLOUD LAYER (TOPS 4000 MSL). CTR ASKED THEIR POS RELATIVE TO BEATRICE AND; SINCE BEATRICE DOES NOT HAVE DME (WHICH THE CTR CTLR DID NOT KNOW); THEY COULD ONLY GIVE CTR AN ESTIMATE. ALTHOUGH CTR HAD CLRED ME TO THE ADVISORY FREQ; I WAS STILL MONITORING CTR AND ADVISED THAT I WAS IMC AND JUST PASSING TO ENE AND DSNDING FROM 3500 TO 1940. CTR ADVISED THE OTHER ACFT TO REMAIN VFR. SHORTLY; I BROKE OUT OF THE OVCST AND HAD THE ARPT IN SIGHT. I RPTED TO CTR THAT I WAS VISUAL AND TO CANCEL IFR. CTR AGAIN ASKED THE OTHER ACFT THEIR POS AND THEN; IN A FEW MINS; ASKED ME MY POS. BY THEN; I WAS ON A HALF MILE FINAL; WHICH I RPTED AND AGAIN REPEATED 'CANCEL IFR.' THERE WERE A LOT OF OTHER ACFT TALKING TO CTR DURING ALL OF THIS TIME; AND ADMITTEDLY; THE CTR CTLR WAS A BUSY MAN. THERE IS ALSO THE POSSIBILITY THAT CTR DID NOT HEAR MY 'CANCEL IFR' EITHER TIME. TO THIS I SHOULD HAVE BEEN ALERT; AS I WAS NOT TOLD TO SQUAWK 1200. IN FACT; IT WASN'T UNTIL I STARTED THIS LAST PARAGRAPH THAT I REALIZED THAT FACT. SO; I MUST SAY THAT I GOOFED. HAVING CANCELLED IFR TWICE WITH CTR; IT DID NOT DAWN ON ME THAT; AS A PRECAUTION; I SHOULD STILL CANCEL WITH COLUMBUS RADIO AS CTR ORIGINALLY INSTRUCTED ME TO DO WHEN I RECEIVED MY APCH CLRNC. AFTER ARRIVING HOME; THE LINE BOY AT THE ARPT CALLED TO TELL ME THAT A SUPVR AT ZMP HAD CALLED ASKING THE WHEREABOUTS OF MY AIRPLANE. THE LINE BOY SAID THAT HE HAD JUST HELPED ME PUT IT IN THE HANGAR. HE SAID THE SUPVR THANKED HIM AND ASKED NO FURTHER QUESTIONS. FROM THIS; I GATHERED THAT CTR WAS NOT SURE WHETHER I HAD AIR CANCELLED; AS NORMALLY FSS WOULD FOLLOW UP ON AN ACFT NOT CLOSING A FLT PLAN. AT ANY RATE; NEXT TIME I WILL REMEMBER THAT IF I DON'T GET A 'SQUAWK 1200;' I MAY NOT HAVE BEEN HEARD. IF THERE IS ANY QUESTION AT ALL; I WILL ALSO CLOSE THROUGH FSS.