GA SMT ALTDEV EXCURSION FROM CLRNC ALT.

Narrative

MY ACFT WAS IN THE #1 POS FOR THE DEP RWY AT WATERLOO; IA; ON NOV/THU/91; MID AFTERNOON; ON AN IFR FLT PLAN FOR OSU ARPT AT COLUMBUS; OH. I HAD REQUESTED FL190. THE PRIMARY RADAR FOR APCH/DEP CTL AT WATERLOO WAS OTS AND CHICAGO CENTER WAS HANDLING ALL THEIR INBOUND/OUTBOUND LOAD. UPON CONTACTING DEP CTL ON 118.9 MHZ; I WAS IMMEDIATELY CLRED TO FL190. THERE WAS MUCH RADIO TFC; WITH INTERRUPTIONS AND 'WALKOVERS.' AS I WAS PASSING ABOUT 8000 FT; CENTER TOLD US TO MAINTAIN 11000 FT. I RPTED LEVEL AT 11000; AND CENTER CALLED OUT OUR TFC AT 11 O'CLOCK; 3 MI; SWBOUND AT 12000 FT. I SAID THAT I HAD THE TFC AND HEARD SOME PARTIALLY BLOCKED EXCHANGE THAT TOLD ME THAT THE OTHER ACFT; WHICH WAS A LARGE CORPORATE TYPE; HAD ME IN SIGHT TOO. THEN CENTER TOLD ME THAT AFTER PASSING THE TFC; I COULD CONTINUE MY CLB TO FL190. I DID HEAR THE WORD 'CLB' AND WORDS 'AFTER PASSING.' I DID NOT HEAR THE WORD 'EXPECT.' AFTER PASSING; WITH THE OTHER ACFT AT 3 O'CLOCK HIGH; I CALLED OUT OF 11000 FOR FL190. BY THIS TIME; THE OTHER ACFT WAS OUT OF MY R VIEW AND ABOUT 2 MI W. CENTER IMMEDIATELY QUESTIONED MY ALT; AND I RESPONDED OUT OF 11000. CENTER AGAIN QUESTIONED MY ALT; AND SAID I WAS TO MAINTAIN 11000. I WAS ABLE TO STOP THE CLB AT 11600 AND TOLD CENTER I HAD UNDERSTOOD I WAS CLRED TO CONTINUE TO CLB TO 190 AFTER PASSING TFC.