Narrative:

We had a normal flight and landing. During our inflight arrival and performance planning there were no indications that any icing conditions existed at [the] airport. Stall protections speeds were utilized due to the common indication from flying through clouds in cold weather flying. Upon landing; runways and taxiways appeared to be completely clear of ice and snow other than a very thin layer of snow in the grass.just after discontinuing reverse thrust at approximately 80 kts. I transferred controls to [the] captain. He continued to slow the aircraft and exited at the intersection. Our estimated ground speed was between 5-10 kts. I hadn't yet turned off any lights and our visibility of the runway exit was good. The intersection appeared to be free of snow and ice. The aircraft was almost completely clear of [the] runway when it began to slide; which we suspect was from black ice. [The] captain attempted to prevent the slide into the grass with continued brake application. We cut the corner of the grass bay and continued to slide onto [the] taxiway where the aircraft regained traction.[the] captain assessed our taxi capability while I contacted tower to inform them of the danger and our departure from the taxiway. Captain was confident in the aircraft's capability to taxi so we continued to the gate. During arrival at the gate; airport operations reported over tower frequency that the taxiway sign had been struck and also that they had failed to de-ice that section of the taxiway. During post flight we only found damage on the bottom side of the right engine cowl. Passengers and flight attendants were unaware that anything had happened.

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Original NASA ASRS Text

Title: E175 First Officer reported that ice on a runway surface resulted in a runway excursion.

Narrative: We had a normal flight and landing. During our inflight arrival and performance planning there were no indications that any icing conditions existed at [the] airport. Stall protections speeds were utilized due to the common indication from flying through clouds in cold weather flying. Upon landing; runways and taxiways appeared to be completely clear of ice and snow other than a very thin layer of snow in the grass.Just after discontinuing reverse thrust at approximately 80 kts. I transferred controls to [the] Captain. He continued to slow the aircraft and exited at the intersection. Our estimated ground speed was between 5-10 kts. I hadn't yet turned off any lights and our visibility of the runway exit was good. The intersection appeared to be free of snow and ice. The aircraft was almost completely clear of [the] runway when it began to slide; which we suspect was from black ice. [The] Captain attempted to prevent the slide into the grass with continued brake application. We cut the corner of the grass bay and continued to slide onto [the] taxiway where the aircraft regained traction.[The] Captain assessed our taxi capability while I contacted Tower to inform them of the danger and our departure from the taxiway. Captain was confident in the aircraft's capability to taxi so we continued to the gate. During arrival at the gate; Airport Operations reported over Tower frequency that the taxiway sign had been struck and also that they had failed to de-ice that section of the taxiway. During post flight we only found damage on the bottom side of the right engine cowl. Passengers and flight attendants were unaware that anything had happened.

Data retrieved from NASA's ASRS site 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.