Narrative:

The event occurred while taxing at night; under constant light braking; on the eastbound taxiway running parallel to runway 29; the intended departure runway. The taxiway had been 'offset plowed' depending on the taxiway; or section of a given taxiway. The centerline of plowed section was either to the right or left of what likely was the actual paved taxiway center line; resulting in compacted/granulated snow remaining over the iced taxiway (as was determined post event). The aircraft was making a slow speed left turn at the farthest east end of that 'right-offset plowed' taxiway running parallel to runway 29 onto the short taxiway which had been 'left-offset plowed' running perpendicular to runway 29 and leading to the hold-short line of that runway. Midway through the left turn the nose of the jet began to slide to the left. As full braking was applied the nose moved slightly ahead and laterally to the left until it came to a stop. Preliminary observation disclosed that the bottom of the left main tire was obscured by what appeared to be a combination of loose and compact snow just to the outside of the cleared portion of the taxiway. The fleet chief pilot on duty was contacted. He advised us that if the aircraft was still on the paved taxiway surface we should have a tug pull the jet clear of the snow bank. At this time it was determined that the left main gear had departed the paved surface of the taxiway approximately 1-1/2 tire widths. A company maintenance tech; with the flight crew and a FBO person's assistance; supervised pulling the jet back several feet; returning the left main gear to the taxiway and allowing for the jet to be tugged forward; then on to the runway and back to the FBO ramp. The notation in the aircraft log book stated that there was no damage to the aircraft and the originally scheduled ferry flight was subsequently completed by the crew the next morning.

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Original NASA ASRS Text

Title: A CE 560XLS flight crew taxied off the paved surface while taxiing for takeoff on partially plowed taxiways.

Narrative: The event occurred while taxing at night; under constant light braking; on the eastbound taxiway running parallel to Runway 29; the intended departure runway. The taxiway had been 'offset plowed' depending on the taxiway; or section of a given taxiway. The centerline of plowed section was either to the right or left of what likely was the actual paved taxiway center line; resulting in compacted/granulated snow remaining over the iced taxiway (as was determined post event). The aircraft was making a slow speed left turn at the farthest east end of that 'right-offset plowed' taxiway running parallel to Runway 29 onto the short taxiway which had been 'left-offset plowed' running perpendicular to Runway 29 and leading to the hold-short line of that runway. Midway through the left turn the nose of the jet began to slide to the left. As full braking was applied the nose moved slightly ahead and laterally to the left until it came to a stop. Preliminary observation disclosed that the bottom of the left main tire was obscured by what appeared to be a combination of loose and compact snow just to the outside of the cleared portion of the taxiway. The Fleet Chief Pilot on duty was contacted. He advised us that if the aircraft was still on the paved taxiway surface we should have a tug pull the jet clear of the snow bank. At this time it was determined that the left main gear had departed the paved surface of the taxiway approximately 1-1/2 tire widths. A company Maintenance Tech; with the flight crew and a FBO person's assistance; supervised pulling the jet back several feet; returning the left main gear to the taxiway and allowing for the jet to be tugged forward; then on to the runway and back to the FBO ramp. The notation in the aircraft log book stated that there was no damage to the aircraft and the originally scheduled ferry flight was subsequently completed by the crew the next morning.

Data retrieved from NASA's ASRS site as of April 2012 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.