Narrative:

During approach and landing, no precipitation. Landing and taxi in were normal although txwys were slick due to compacted snow. As passenger were deplaning, a light snow shower arrived and lasted for a short time. I returned to the aircraft approximately 30 mins before departure. The snow had stopped falling. I asked the so if there was snow on the aircraft and a need for deicing. He said there was no snow on the aircraft except for a little on top of the wing. He thought there was no need to deice as the temperature was approximately 20 degrees F, with only a little light snow on top of the wing which was not sticking as he had checked it with his hand. I inspected the aircraft and found it to be as described. The fuselage, engines, tail, leading edge and under wing were clean and dry. There was a dusting on top of the cold wing which was not sticking and would easily blow off. I agreed there was no need to deice. As we taxied for takeoff I saw a few aircraft being deiced. We made a normal takeoff with engine anti-ice on. The question occurred to me later -- was there something I didn't think of? I consulted the operating manual and found it states that with the 'clean aircraft concept,' the aircraft must be free of ice and snow (from any contamination) prior to takeoff. I knew this, yet I thought I would make a judgement in a situation as this one that is not allowed. I should have deiced. I had erred by slipping into the way we 'used to do it.'

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Original NASA ASRS Text

Title: AN ACR LGT CAPT TOOK OFF WITH A LIGHT DUSTING OF SNOW ON HIS WINGS. THE ACFT WAS OTHERWISE CLEAN. ERROR ADMITTED.

Narrative: DURING APCH AND LNDG, NO PRECIP. LNDG AND TAXI IN WERE NORMAL ALTHOUGH TXWYS WERE SLICK DUE TO COMPACTED SNOW. AS PAX WERE DEPLANING, A LIGHT SNOW SHOWER ARRIVED AND LASTED FOR A SHORT TIME. I RETURNED TO THE ACFT APPROX 30 MINS BEFORE DEP. THE SNOW HAD STOPPED FALLING. I ASKED THE SO IF THERE WAS SNOW ON THE ACFT AND A NEED FOR DEICING. HE SAID THERE WAS NO SNOW ON THE ACFT EXCEPT FOR A LITTLE ON TOP OF THE WING. HE THOUGHT THERE WAS NO NEED TO DEICE AS THE TEMP WAS APPROX 20 DEGS F, WITH ONLY A LITTLE LIGHT SNOW ON TOP OF THE WING WHICH WAS NOT STICKING AS HE HAD CHKED IT WITH HIS HAND. I INSPECTED THE ACFT AND FOUND IT TO BE AS DESCRIBED. THE FUSELAGE, ENGS, TAIL, LEADING EDGE AND UNDER WING WERE CLEAN AND DRY. THERE WAS A DUSTING ON TOP OF THE COLD WING WHICH WAS NOT STICKING AND WOULD EASILY BLOW OFF. I AGREED THERE WAS NO NEED TO DEICE. AS WE TAXIED FOR TKOF I SAW A FEW ACFT BEING DEICED. WE MADE A NORMAL TKOF WITH ENG ANTI-ICE ON. THE QUESTION OCCURRED TO ME LATER -- WAS THERE SOMETHING I DIDN'T THINK OF? I CONSULTED THE OPERATING MANUAL AND FOUND IT STATES THAT WITH THE 'CLEAN ACFT CONCEPT,' THE ACFT MUST BE FREE OF ICE AND SNOW (FROM ANY CONTAMINATION) PRIOR TO TKOF. I KNEW THIS, YET I THOUGHT I WOULD MAKE A JUDGEMENT IN A SIT AS THIS ONE THAT IS NOT ALLOWED. I SHOULD HAVE DEICED. I HAD ERRED BY SLIPPING INTO THE WAY WE 'USED TO DO IT.'

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.