Flight Crew Air Transport Pilot (ATP)
Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Taxiway
General Flight Cancelled / Delayed
Weather; Airport
After engine start it started lightly raining. I inspected the front aircraft surfaces including the radardome; wipers; and the non-heated aft window to determine if the rain was freezing and it was not. Also I opened the window and felt the lower fuselage [which] was wet with no ice present. As we taxied out to runway 01L via Charlie Delta we observed a car on the runway doing a contamination check. The aircraft was readied for takeoff and we were informed 01L was now closed with Mu reading below 20. We inquired about 1R and we were told it was chemically treated and may be better. I decided to taxi down 1L toward the ramp. During the taxi; First Officer (FO) and I discussed the need to deice before departure and whether or not to taxi directly back to the ramp. Tower instructed us to exit 01L at Bravo while we formulated a plan of action. Taxi to 01L and the taxi down 01L were normal with braking action fair. The turn on to Bravo was normal. Once on Bravo the aircraft started to slide and weather vane. I used a little differential thrust and braking to try to keep the aircraft on the centerline but the right downwind wheels left the taxiway. I set the parking brake and made a PA announcement to the pasengers informing them of the situation. We informed the tower of the situation and reported braking action on Bravo was nil. [A few minutes later] we were informed by the tower that the airport was closed with braking actions on all runways nil. A Medivac [aircraft] diverted and after about 30 minutes of worsening conditions an [air carrier] jet diverted also. From the time of the incident till when we departed for the hotel no other aircraft took off or landed in the airport remain closed.Initial reports from ground personnel stated that the #4 wheel was off the taxiway but after further inspection both wheels were in the dirt. The wind was 90deg off the left wingtip at 30+ gusting to 40. This force kept pushing and digging in the right wheels. Multiple PA's were make and the Passengers were kept informed thought the process. (FO) and I coordinated with tower/ground control; company operations; fire and rescue; company dispatch; Maintenance control; and the duty pilot. Logbook write-ups were made. We initially planned to tug the aircraft back onto the taxiway and tow it to the gate with passengers onboard but the presence of freezing rain and the condition of the taxiways made that impossible. After consulting Maintenance control we decided to bus the passengers to the terminal after the taxiways were deiced and cleared. Company personnel arrived and dropped the aft stairs and I consulted face to face with fire rescue and solidified the plan to deplane the passengers. While the busses were readied; I completed a walk around and installed the gear pin at the direction of Maintenance control. I then made a logbook write-up reflecting that. The taxiways needed to be deiced before the busses could safely be brought to the rear of the aircraft. All passengers and crew were deplaned without incident and injury. (FO) and I volunteered to stay behind and ride the brakes for maintenance control. I sent the flight attendants to the hotel and (FO) and I stayed behind. After approximately 45 minutes taxiway Bravo was deiced and a tug was attached to the airplane. After several attempts to pull the airplane out; the wheels appeared to be frozen in place and the tug was having trouble gaining traction. The decision was made to leave the airplane where it was. I called maintenance control to remind them to drain the potable water system due to the cold weather. After the situation was again reviewed with the mechanic on site we have left the airplane in his care with the APU running; packs on; all other systems secured.
Captain reported his aircraft slid off the taxiway in icy conditions.