Large Transport; Low Wing; 2 Turbojet Eng
Time Pressure; Distraction; Confusion; Communication Breakdown; Workload
ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Human Factors; Procedure; Company Policy; Airport
We were late pushing off the gate at Midway and could not push deep enough to let holding traffic get onto our gate. Aircraft holding for gates had several aircraft stacked behind them. Airport was very busy with lots of radio chatter of aircraft trying to push and taxi. The First Officer (FO) had made several calls to Ground for taxi clearance; but; so was everyone else. I knew we were blocking a lot of traffic and I was trying to monitor Ground and Ops at the same time. After several attempts by FO; I thought I heard our call sign cleared to taxi. So believing I was cleared; and because I felt rushed; I didn't confirm with FO we had been cleared to taxi; I started to turn out on to the Taxiway. At that point; Ground informed me we had been not cleared to taxi.Never rush! I should have focused all my attention monitoring Ground in that busy environment. If I wasn't positive I should have reconfirmed clearance my FO and reconfirmed with Ground Control that we had taxi clearance. My FO should have stopped me from taxiing if he wasn't positive we had clearance.
A Pilot reported MDW radio and aircraft traffic gridlocked. He became confused and thought taxi clearance was issued but after moving was stopped by Ground.