PUSHBACK CLRNC CONFUSION WITH B757 DEPARTING MDW.

Narrative

AT APPROX A50 ON THE EVENING OF MAR/THU/03; WE WERE READY TO PUSH BACK FROM THE NEW GATE AT MDW ARPT. THE PLANE THAT WE WERE IN HAD AN INOP PNEUMATIC FUNCTION ON THE APU. THEREFORE; WE HAD TO START ONE OF THE ENGS AT THE GATE WITH AN AIR START. I ASKED THE GND CTLR; WHO WAS ALSO CLRNC; TWR; ETC; IF WE COULD START AN ENG AT THE GATE. HE REPLIED 'I HAVE NO CTL OVER THAT; GIVE ME A CALL WHEN YOU'RE READY TO TAXI.' I THOUGHT THAT THIS WAS A BIT ODD. I REPEATED WHAT WAS SAID TO THE CAPT. HE SAID THAT THAT WAS OK. WE PROCEEDED TO START THE R ENG AT THE GATE. WE THEN PROCEEDED TO PUSH BACK FROM GATE ONTO TXWY Y. WE THEN CONDUCTED A XBLEED START ON THE L ENG. THE PUSH CREW DISCONNECTED. THE GND CTLR THEN ASKED WHO WAS PARKED ON TXWY Y. I TOLD HIM THAT WE WERE. HE THEN TOLD US THAT WE WERE NOT GIVEN PERMISSION TO PUSH BACK ONTO ACTIVE TXWY Y AND THAT; IN THE FUTURE; WE NEED TO CHK WITH HIM. I SIMPLY RESPONDED WITH OUR CALL SIGN. HE THEN GAVE US TAXI INSTRUCTIONS TO THE ACTIVE RWY. I BELIEVE THAT THE ROOT OF THE PROB WAS THE CTLR BEING OVERWORKED. HE WAS EXTREMELY BUSY; BECAUSE AT THAT TIME OF NIGHT THEY GO TO ONE CTLR AT MIDWAY. THAT IS ONE CTLR TO HANDLE ALL CLRNCS; GND; AND TWR. I THINK THAT HE MEANT TO TELL US TO CALL HIM WHEN WE WERE READY TO PUSH; BUT HE ACTUALLY TOLD US TO CONTACT HIM WHEN READY TO TAXI. I THINK THE PROB CAN BE CORRECTED BY WAITING UNTIL LATER IN THE EVENING; WHEN TFC FLOW IS LOWER; BEFORE GOING TO ONE CTLR OPS.