Narrative:

Winter storm conditions were in effect at ZZZ that at push from the gate was moderate rain and ice pellets. During taxi; it changed over to blowing moderate wet snow; lengthy delays for deicing; temperature +2 degrees C; and a gate return was forced once taxi fuel burnout became excessive. After returning to the gate; I (the jumpseater) stepped out onto the jet bridge to inspect the wing for ice/snow to see how well we did 1 hour after a 2 step deicing/anti-icing and still within the holdover time. I found the top of the wing clean; but the entire length of the leading edge was impacted with snow. The captain had followed procedures for winter operations; kept alert with changing weather conditions; and was very aware of holdover times and an effectiveness of type 4 anti-icing fluid properties. Since snowfall had tapered off somewhat; he was ok with going longer into the holdover range. Yet in spite of this; I found the leading edge was contaminated upon returning to the gate. I believe the contaminated leading edge is the result of an industry misconception about the re-accumulation of contaminants on a clean wing. Most of the wing surface is horizontal and had a type 4 deicing fluid lying on top of it. The leading edge surfaces having been set for takeoff; sit in a near vertical position so it readily allows for gravity runoff of fluids; leaving the leading edge unprotected but still within the holdover range for a fluid which is missing from this portion of the wing. In spite of their best efforts; situational awareness; and strict adherence to company procedures for winter operations; they believe they were good to go for takeoff. A visual inspection of the wing just prior to takeoff would have easily spotted the contaminated leading edge; but not required according to procedure.

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Original NASA ASRS Text

Title: Following lengthy ground delays in blowing snow the A319 flight crew returned to the gate to be de-iced a second time. Visual inspection of the wing leading edge discovered ice the length of both wings despite a time interval of less than the calculated holdover time.

Narrative: Winter storm conditions were in effect at ZZZ that at push from the gate was moderate rain and ice pellets. During taxi; it changed over to blowing moderate wet snow; lengthy delays for deicing; temperature +2 degrees C; and a gate return was forced once taxi fuel burnout became excessive. After returning to the gate; I (the Jumpseater) stepped out onto the jet bridge to inspect the wing for ice/snow to see how well we did 1 hour after a 2 step deicing/anti-icing and still within the holdover time. I found the top of the wing clean; but the entire length of the leading edge was impacted with snow. The Captain had followed procedures for winter operations; kept alert with changing weather conditions; and was very aware of holdover times and an effectiveness of Type 4 anti-icing fluid properties. Since snowfall had tapered off somewhat; he was OK with going longer into the holdover range. Yet in spite of this; I found the leading edge was contaminated upon returning to the gate. I believe the contaminated leading edge is the result of an industry misconception about the re-accumulation of contaminants on a clean wing. Most of the wing surface is horizontal and had a Type 4 deicing fluid lying on top of it. The leading edge surfaces having been set for takeoff; sit in a near vertical position so it readily allows for gravity runoff of fluids; leaving the leading edge unprotected but still within the holdover range for a fluid which is missing from this portion of the wing. In spite of their best efforts; situational awareness; and strict adherence to company procedures for winter operations; they believe they were good to go for takeoff. A visual inspection of the wing just prior to takeoff would have easily spotted the contaminated leading edge; but not required according to procedure.

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.