Date: 202001
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: IMC
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Situational Awareness
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Taxiway
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Gate; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Weather; Airport; Human Factors
Primary problem: Airport

Narrative: We were delayed several hours because the airport was closed due to airport conditions associated with a winter storm. The airplane had a deferred thrust reverser so we had to wait for the RCCs on the field to be 5/5/5 or better. We had to delay the flight while we waited for airport operations to improve the runways. When we finally managed to get the runway requirements necessary for our operational needs; we pushed back from the gate. We needed to get deiced with type I and IV due to blowing snow and flurries in the vicinity. When we reviewed the NOTAMs for the airport; we had noted that all taxiways we were operating on had medium to poor braking action so I decided to turn the plane into the wind on the ramp in order to clear our engines because the ramp seemed more suitable than any taxiway we were traversing on. We two engine taxied due to contamination and the FFOD checks. After we cleared the engines; we continued to taxi [and] I noted the poor conditions. Tower had advised us that we had a wheels up time in 3-5min. My First Officer alerted the Tower that we were probably not going to make the time due to our slow taxi and poor taxiway conditions. I had noted a slight improvement to taxi conditions but became wary when I saw a downslope. I slowed down to a crawl before entering the downslope and lost all directional control due to unreported nil braking action and a 41 kt wind pushing us clockwise. I tried my best to stop the skid but the wind and ice had conspired against us. We came to a rest when our left main gained traction on the grass and we had gone off the taxiway about 6 inches. I then shut down both engines and coordinated to safely remove passengers to the terminal and find a way to pull the airplane out of the grass. There were no injuries; no aircraft damage; and no airport damage reported.Inadequate taxiway friction reports led the crew to believe that they could continue to taxi to a runway when they should have picked an alternate route due to unreported NIL braking action. The crew taxied slowly and used a two engine taxi [in accordance with] policy. Alternate methods were used in order to accomplish tasks that required good braking action (clearing engines after deice; taking care of most tasks while not moving to limit heads down operations).After the event; airport operations promptly came to the area where the incident occurred and spent some time sanding down and salting the taxiway. This proved that they did not accurately report the braking action and were trying to cover their tracks before airport police and other officials came. Even after the taxiways were sanded and salted; the emergency vehicles were still sliding around and the officers were struggling to maintain traction while documenting the events.


Second narrative: Very slow taxi ~3-4mph; Medium-poor braking reported on the field. While on '[Taxiway X]' ATC ground control advised us of a release time [that was only] 5 minutes from current time. Crew advised ATC that due to slow taxiing there was the possibility that window would not be made due to taxi conditions. While taxiing the plane was brought to a complete stop multiple times to ensure adequate braking. A slight downhill was encountered; the plane was slowed to a crawl to ensure safety. At that point the wind weather-vaned the aircraft perpendicular to the taxiway; braking was found to be nil; and the plane slid back to a stop. The left main outboard tire left the taxiway and settled on the grass ~6inches.ATC was notified that we would be unable to continue and would need a tug to move the aircraft. Station operations; Company; and ATC were notified of the situation. Airport operations started continually salting the taxiway after the excursion. Operations arrived with a bus for the passengers who were deplaned and transported to the terminal safely. The plane was tugged out by maintenance and returned to the gate safely. No crew or passengers were injured and there was no apparent damage to the aircraft or airport facilities.


Synopsis: CRJ flight crew reported that high winds and poor traction resulted in a taxiway excursion.