Narrative:

I was working all radar positions combined. The aircraft departed. Before I took over the position; the previous controller cleared the aircraft to the first fix on his route and issued a climb to 8000 feet. When the aircraft was at approximately 5500 feet he asked me to make 6000 feet his final altitude. I cleared him to maintain 6000 feet. The handoff to the adjacent center sector was normal. Approximately 3 to 5 minutes after I had switched the aircraft to the new sector's frequency; that sector called to request control of the aircraft. The aircraft had developed ice at 6000 feet and needed to descend. I gave control to the adjacent controller. I observed the aircraft descend and begin to turn around. The center controller called back to update the aircraft's status; letting me know the aircraft needed to turn around and asked what my lowest IFR altitude was in the area. I told [the other controller] 5000 feet. I observed the aircraft continuing to descend through 4500 feet. The center controller called back and told me the aircraft needed to continue descending. I took radar contact and let the controller in charge know I was declaring [a serious situation] for the aircraft. The aircraft checked in and told me he was descending. I gave him the altimeter and asked for his intentions. He told me he needed to keep descending. I told him the lowest safe IFR altitude in his area was 5000 feet and that approximately 4 miles ahead of his current track the lowest safe IFR altitude dropped to 3400 feet. He said roger. I observed the aircraft continuing to descend through 3500 feet and I asked for his flight conditions. He said he was below the clouds and VFR in light rain. I asked again for his intentions. He said he wanted to fly VFR eastbound. I verified he was cancelling IFR and he replied affirmative. Soon after his IFR cancellation I lost radar contact as he descended through 2500 feet. The aircraft continued VFR southbound along the river.looking back; I should have asked for the pilot's flight conditions after he leveled at 6000 feet. If I had known he was getting ice I could have started working the problem while the aircraft was in an area of lower terrain. A key part of this situation was the pilot's delay in alerting ATC of his situation. By the time he asked the center sector for a lower altitude; he was in an area of higher terrain. Lastly; I should have verified the aircraft's distress status when coordinating with the center controller. I found out later [the controller] had declared [a serious situation] for the pilot before I took radar contact.

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Original NASA ASRS Text

Title: Controllers and SR20 pilot reported the aircraft descended below the Minimum IFR Altitude due to icing conditions.

Narrative: I was working all radar positions combined. The aircraft departed. Before I took over the position; the previous controller cleared the aircraft to the first fix on his route and issued a climb to 8000 feet. When the aircraft was at approximately 5500 feet he asked me to make 6000 feet his final altitude. I cleared him to maintain 6000 feet. The handoff to the adjacent Center sector was normal. Approximately 3 to 5 minutes after I had switched the aircraft to the new sector's frequency; that sector called to request control of the aircraft. The aircraft had developed ice at 6000 feet and needed to descend. I gave control to the adjacent controller. I observed the aircraft descend and begin to turn around. The Center controller called back to update the aircraft's status; letting me know the aircraft needed to turn around and asked what my lowest IFR altitude was in the area. I told [the other controller] 5000 feet. I observed the aircraft continuing to descend through 4500 feet. The Center controller called back and told me the aircraft needed to continue descending. I took radar contact and let the Controller in Charge know I was declaring [a serious situation] for the aircraft. The aircraft checked in and told me he was descending. I gave him the altimeter and asked for his intentions. He told me he needed to keep descending. I told him the lowest safe IFR altitude in his area was 5000 feet and that approximately 4 miles ahead of his current track the lowest safe IFR altitude dropped to 3400 feet. He said roger. I observed the aircraft continuing to descend through 3500 feet and I asked for his flight conditions. He said he was below the clouds and VFR in light rain. I asked again for his intentions. He said he wanted to fly VFR eastbound. I verified he was cancelling IFR and he replied affirmative. Soon after his IFR cancellation I lost radar contact as he descended through 2500 feet. The aircraft continued VFR southbound along the river.Looking back; I should have asked for the pilot's flight conditions after he leveled at 6000 feet. If I had known he was getting ice I could have started working the problem while the aircraft was in an area of lower terrain. A key part of this situation was the pilot's delay in alerting ATC of his situation. By the time he asked the Center sector for a lower altitude; he was in an area of higher terrain. Lastly; I should have verified the aircraft's distress status when coordinating with the Center controller. I found out later [the controller] had declared [a serious situation] for the pilot before I took radar contact.

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.