A320
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 150; Flight Crew Total 18000; Flight Crew Type 5500
Ground Event / Encounter Other / Unknown; Ground Excursion Taxiway; Inflight Event / Encounter Loss Of Aircraft Control
Flight Crew Returned To Gate; General Flight Cancelled / Delayed
Airport; Weather
We pushed back from the gate and getting underway was a tedious process due to the severe cold; ineptitude of the ramp personnel; and the usual slow ACARS performance with takeoff data. Due to the horrendous [winter] conditions of the night before we planned to start both engines; let everything warm up slowly; and carefully taxi out due to expected poor braking action on the apron and taxiways. We were cleared to Runway XX via Taxiway XX and X. As we slowly transitioned from the apron to Taxiway XX the aircraft began to skid toward Taxiway X. I tried to arrest the skid by reapplying the brakes and tried to steer the aircraft onto Taxiway X but braking action was NIL and the airplane continued to slide down the slightest incline on XX from the apron to X. The airplane came to a stop at an angle with the nose gear and left main gear in the snow on the left side of Taxiway X. We did not know at the time if we were off the hard surface so we started the APU; shut down the engines; and notified the flight attendants and passengers as to what had just happened. We sent Dispatch a message through ACARS that we slid off the taxiway and he started coordinating with Flight Operations managers and Maintenance with regard to moving the airplane. We also notified Ground and they sent an OPS vehicle to meet us and gave us a discrete frequency to communicate on. The Operations people told us that our nose gear was about two feet into a snow bank with snow up to the axle. He said the left main gear was on the edge of the snow bank and that the aircraft was still on the taxiway surface. He called for a front end loader to remove the snow in front of the aircraft so the tug could pull us back to the gate. The tug pulled us to the gate without further incident.
ATIS reported slippery conditions all taxiways. It was late evening and the temperature was approximately -18C. The Polar Vortex weather conditions that we experienced on arrival the night prior were still present; but there was no precipitation and visibility was good. The pavement appeared patchy ice and dry.
An A320; taxiing for takeoff during extreme winter field conditions lost traction; slid into a snow bank with the nose gear off the hard surface.