Narrative:

After deicing the aircraft, I proceeded to ask ground control for the RVR values on runway 5R. The RVR values were not good for takeoff but the captain decided to taxi out just in case they will come up. Ground clearance directed us to taxi to runway 5R via lima taxiway. As we taxied out we noticed that the ramp taxiways were not snow plowed. I asked the captain why he was not joining lima taxiway the most expeditious way which was straight out. The captain response was that he had decided to join taxiway lima at sierra through the main ramp. I continued to monitor for visual clues and looking for taxiway sierra. At this moment WX condition were deteriorating rapidly. The captain pointed out what he believed was sierra taxiway, and proceeded toward the taxiway. I continued monitoring for visual clues and realized that we were heading in the wrong direction; and yelled stop. At this point, the aircraft was already off the taxiway and stuck in the snow. We proceeded to evacuate/evacuation the passengers; no emergency evacuate/evacuation was performed. No aircraft damage nor passenger injuries were reported. I believe the factors that affected our performance were the low visibility and that the ramp and taxiways have not been snow plowed which made our depth perception hard to judge. Supplemental information from acn 205369. We chose to exit ramp area at 'sierra' taxiway transition to 'lima.' we turned onto what was determined and agreed to be 'sierra' taxiway, and begun to snow plow, bogging down to a stop. However, crew was very unfamiliar with airport, and there was very little guidance from physical dimensions, markers, reference points, due to the snow. Taxiway identifiers were snow covered, and taxi lights did not appear to be illuminated at time of incident. Ramp was plowed shortly thereafter, however, and taxi lights were turned on. There was no damage or injuries.

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Original NASA ASRS Text

Title: TAXIWAY EXCURSION.

Narrative: AFTER DEICING THE ACFT, I PROCEEDED TO ASK GND CTL FOR THE RVR VALUES ON RWY 5R. THE RVR VALUES WERE NOT GOOD FOR TKOF BUT THE CAPT DECIDED TO TAXI OUT JUST IN CASE THEY WILL COME UP. GND CLRNC DIRECTED US TO TAXI TO RWY 5R VIA LIMA TAXIWAY. AS WE TAXIED OUT WE NOTICED THAT THE RAMP TAXIWAYS WERE NOT SNOW PLOWED. I ASKED THE CAPT WHY HE WAS NOT JOINING LIMA TAXIWAY THE MOST EXPEDITIOUS WAY WHICH WAS STRAIGHT OUT. THE CAPT RESPONSE WAS THAT HE HAD DECIDED TO JOIN TAXIWAY LIMA AT SIERRA THROUGH THE MAIN RAMP. I CONTINUED TO MONITOR FOR VISUAL CLUES AND LOOKING FOR TAXIWAY SIERRA. AT THIS MOMENT WX CONDITION WERE DETERIORATING RAPIDLY. THE CAPT POINTED OUT WHAT HE BELIEVED WAS SIERRA TAXIWAY, AND PROCEEDED TOWARD THE TAXIWAY. I CONTINUED MONITORING FOR VISUAL CLUES AND REALIZED THAT WE WERE HDG IN THE WRONG DIRECTION; AND YELLED STOP. AT THIS POINT, THE ACFT WAS ALREADY OFF THE TAXIWAY AND STUCK IN THE SNOW. WE PROCEEDED TO EVAC THE PAXS; NO EMER EVAC WAS PERFORMED. NO ACFT DAMAGE NOR PAX INJURIES WERE RPTED. I BELIEVE THE FACTORS THAT AFFECTED OUR PERFORMANCE WERE THE LOW VISIBILITY AND THAT THE RAMP AND TAXIWAYS HAVE NOT BEEN SNOW PLOWED WHICH MADE OUR DEPTH PERCEPTION HARD TO JUDGE. SUPPLEMENTAL INFO FROM ACN 205369. WE CHOSE TO EXIT RAMP AREA AT 'SIERRA' TAXIWAY TRANSITION TO 'LIMA.' WE TURNED ONTO WHAT WAS DETERMINED AND AGREED TO BE 'SIERRA' TAXIWAY, AND BEGUN TO SNOW PLOW, BOGGING DOWN TO A STOP. HOWEVER, CREW WAS VERY UNFAMILIAR WITH ARPT, AND THERE WAS VERY LITTLE GUIDANCE FROM PHYSICAL DIMENSIONS, MARKERS, REF POINTS, DUE TO THE SNOW. TAXIWAY IDENTIFIERS WERE SNOW COVERED, AND TAXI LIGHTS DID NOT APPEAR TO BE ILLUMINATED AT TIME OF INCIDENT. RAMP WAS PLOWED SHORTLY THEREAFTER, HOWEVER, AND TAXI LIGHTS WERE TURNED ON. THERE WAS NO DAMAGE OR INJURIES.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.