RPTR'S ACFT X WAS CLRED TO 11000 FT; FLC WAS UNSURE OF ASSIGNED ALT; SO LEVELED OFF AT 12000 FT.

Narrative

ON JUN/XA/99; THE FLT WAS UNDER MY COMMAND FROM COLUMBUS; OH; TO DETROIT. WE WERE FLYING DAY 3 OF A 3-DAY TRIP; LEG 3 OF 5. I WAS THE PNF FOR THIS PARTICULAR LEG. ISOLATED STORM CELLS IN THE IMMEDIATE AREA OF THE COLUMBUS ARPT WERE CAUSING MINOR DEVS IN ROUTINGS. WE WERE CLRED TO CLB TO 10000 FT AFTER A NORMAL DEP OFF OF RWY 28L. DEP CTL GAVE US A TURN FROM RWY HEADING TO THE NE. WE ENCOUNTERED BUILDUPS AND REQUESTED HEADING CHANGES TO AVOID THEM. A COUPLE OF HEADING CHANGES WERE ASSIGNED DURING THE CLB. THE WX BEGAN TO CLR OF BUILDUPS AS WE TURNED TO THE NW TOWARD KIRBY INTXN. I BECAME UNCERTAIN AS TO THE LAST ASSIGNED ALT; WHICH WAS ASSIGNED LATE IN THE CLB. THE DEP FREQ HAD BECOME VERY BUSY AND I WAS UNABLE TO REQUEST A CONFIRMATION OF THE ALT ASSIGNED; HOWEVER; I BELIEVED WE HAD BEEN ASSIGNED TO 12000 FT. THE FREQ FINALLY HAD A BREAK IN THE VOICE TFC AND I ASKED WHAT OUR ASSIGNMENT WAS. HE STATED IT WAS 11000 FT AND NOTED WE WERE AT 12000 FT. HE FURTHER NOTED THAT THERE HAD BEEN NO TFC CONFLICT AND THAT WE SHOULD REMAIN AT 12000 FT. WE CONTINUED WITH THE IMPRESSION THAT WAS THE END OF THE MATTER.