Narrative:

We had an interesting icing event with 737 last night that you need to be aware of. After a long transcontinental flight at the upper flight levels; a preflight was performed immediately after landing. Airport info reported 2;500 ft broken 06/01 (42.8/33.8 F). No frost was present on the underside of the wings. No contamination was visible anywhere on the walk-around inspection. A view of the wings from the cabin was not performed with an OAT above 40 degrees F. During push a deadheading flight attendant alerted us to ice on the top of the right wing. Although I thought it very unlikely that ice was present; I performed an inspection from cabin and asked the first officer to look after I did. While we did see a 2 ft x 2 ft irregularly shaped area mid chord just behind the #2 engine (right wing only); I still thought it unlikely that this could be ice. I though it may have been a paint adhesion issue. To be sure I asked for an inspection from the ground and the result was still inconclusive. We were towed back into the gate and a certified de-icer performed an inspection. Even with the use of a ladder; a suitable view was not obtained. The de-ice truck basket was deployed. The inspector had these comments; 'captain; you have a load of ice. I've never seen anything like this before.' interesting points [to make]: outside air temperature [was] well above freezing; [there was] no leading edge contamination; no frost on underside of wing; significant temp/dew point spread; very low fuel levels; approximately 7.0 fob and 11.5 (10.5 mto) release fuel. No significant icing on arrival. Preflight [was] performed soon after arrival. I have noted a number of our aircraft have tail horizontal stabilizer leading edge dents; including this one (also right side). It is curious that these dents seem to be occurring at a higher rate than the wings (bird strike) and that ground impacts would be hard to explain on the tail. Could we have an issue similar to the MD80 with ice forming in the top of a super-cooled wing only to break off on rotation and hitting the tail? As the chief pilot pointed out; the fact that very little fuel was added could explain a wing far cooler than the dew point and well below freezing. At a minimum we need to look at the upper surface of the wing at higher OAT's on other than first flight of the day. Change manual to higher OAT cabin inspection.

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Original NASA ASRS Text

Title: Subsequent to a transcontinental flight; and on the subsequent leg on pushback for flight with a 42 degrees F OAT; B737-800 was found to have 1/8 to 1/4 inch of ice on the right wing only. The aircraft was returned to the gate for de-icing.

Narrative: We had an interesting icing event with 737 last night that you need to be aware of. After a long transcontinental flight at the upper flight levels; a preflight was performed immediately after landing. Airport info reported 2;500 FT BKN 06/01 (42.8/33.8 F). No frost was present on the underside of the wings. No contamination was visible anywhere on the walk-around inspection. A view of the wings from the cabin was not performed with an OAT above 40 degrees F. During push a deadheading Flight Attendant alerted us to ice on the top of the right wing. Although I thought it very unlikely that ice was present; I performed an inspection from cabin and asked the First Officer to look after I did. While we did see a 2 FT x 2 FT irregularly shaped area mid chord just behind the #2 engine (right wing only); I still thought it unlikely that this could be ice. I though it may have been a paint adhesion issue. To be sure I asked for an inspection from the ground and the result was still inconclusive. We were towed back into the gate and a certified de-icer performed an inspection. Even with the use of a ladder; a suitable view was not obtained. The de-ice truck basket was deployed. The inspector had these comments; 'Captain; you have a load of ice. I've never seen anything like this before.' Interesting points [to make]: outside air temperature [was] well above freezing; [there was] no leading edge contamination; no frost on underside of wing; significant temp/dew point spread; very low fuel levels; approximately 7.0 FOB and 11.5 (10.5 MTO) release fuel. No significant icing on arrival. Preflight [was] performed soon after arrival. I have noted a number of our aircraft have tail horizontal stabilizer leading edge dents; including this one (also right side). It is curious that these dents seem to be occurring at a higher rate than the wings (bird strike) and that ground impacts would be hard to explain on the tail. Could we have an issue similar to the MD80 with ice forming in the top of a super-cooled wing only to break off on rotation and hitting the tail? As the Chief Pilot pointed out; the fact that very little fuel was added could explain a wing far cooler than the dew point and well below freezing. At a minimum we need to look at the upper surface of the wing at higher OAT's on other than first flight of the day. Change manual to higher OAT cabin inspection.

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.