Narrative:

I sat down on the radar position; relieving the radar and radar-associate position. There was a large area of moderate to heavy with a little bit of extreme precipitation in the area. Therefore; with the outside temperatures; I knew that icing could be a problem but I had received no reports of icing. Aircraft X was on frequency flying at 8000 enroute to abc. I advised aircraft X about the large area of moderate/heavy/extreme precipitation along his route of flight. Aircraft X asked me what altitudes the precipitation was at. I advised aircraft X that I only showed this precipitation FL240 and below. I told him that I did not have a stratification lower than this. Aircraft X asked to deviate to the east. I cleared aircraft X to deviate east when able direct abc; maintain 8000. Aircraft X accepted this clearance and started deviating eastward. His route of flight kept taking him further east; away from the depicted precipitation. I rerouted his flight plan so it would process into the proper approach control. I was working several other aircraft also deviating and departures off of the terminal airport; when aircraft X called on saying that he had ice on his wheels and wanted to return to ZZZ. I vectored aircraft X towards ZZZ and descended him to 4000. Aircraft X took the clearance and started descending. I asked aircraft X what kind of ice (light rime) and the outside air temp (minus 3). I submitted the PIREP. I called in the versi time to ZZZ tower for aircraft X. When aircraft X was around 7000; I asked him if he still had the ice. He said that the ice was off his wheels. I was then still vectoring aircraft X for ILS3 at ZZZ. I was working other aircraft and even a departure off of ZZZ. Aircraft X called on about 20nm south of ZZZ saying that he was losing airspeed and altitude. I advised him that the MEA was 2900. (The supervisor at this time got me a d-side.) I read him the weather at ZZZ. ZZZ was the closest airport for aircraft X. I called ZZZ tower and asked him for the information around the airport. Tower said that the airport was clear to the northwest. Aircraft X was descending below 2900 and climbing back up. He was flying westbound when had cleared him northbound to ZZZ. At one point aircraft X was down to 2100 and then I saw his mode C read 3200. I advised aircraft X that the closest aircraft to him was an aircraft at FL200. I told aircraft X to do what he needed to do; meaning that if he needed to climb that it would be approved. I should have then reiterated the MEA was 2900. Aircraft X finally was able to fly to the airport. I gave him the weather again and told him that tower said it was clear to the northwest. Tower approved for me to keep aircraft X coming in. Aircraft X finally got the airport in sight and I cleared him for visual approach to runway 3 at ZZZ. I switched him to tower and tower called when he landed safely. Recommendation; when I told aircraft X to do what he needed to do; I should have told him that he may climb to any altitude he needs. I could have assigned him a block altitude. What I needed to make sure he understood was that at all times the minimum safe altitude was 2900. I should have asked for a d-side when aircraft X was picking up ice because it took me some time to enter the PIREP.

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Original NASA ASRS Text

Title: Enroute controller described icing event when a small aircraft was provided assistance; the pilot indicating a loss of airspeed and altitude.

Narrative: I sat down on the radar position; relieving the radar and radar-associate position. There was a large area of moderate to heavy with a little bit of extreme precipitation in the area. Therefore; with the outside temperatures; I knew that icing could be a problem but I had received no reports of icing. Aircraft X was on frequency flying at 8000 enroute to ABC. I advised Aircraft X about the large area of moderate/heavy/extreme precipitation along his route of flight. Aircraft X asked me what altitudes the precipitation was at. I advised Aircraft X that I only showed this precipitation FL240 and below. I told him that I did not have a stratification lower than this. Aircraft X asked to deviate to the east. I cleared Aircraft X to deviate east when able direct ABC; maintain 8000. Aircraft X accepted this clearance and started deviating eastward. His route of flight kept taking him further east; away from the depicted precipitation. I rerouted his flight plan so it would process into the proper Approach Control. I was working several other aircraft also deviating and departures off of the terminal airport; when Aircraft X called on saying that he had ice on his wheels and wanted to return to ZZZ. I vectored Aircraft X towards ZZZ and descended him to 4000. Aircraft X took the clearance and started descending. I asked Aircraft X what kind of ice (light rime) and the outside air temp (minus 3). I submitted the PIREP. I called in the VERSI time to ZZZ TWR for Aircraft X. When Aircraft X was around 7000; I asked him if he still had the ice. He said that the ice was off his wheels. I was then still vectoring Aircraft X for ILS3 at ZZZ. I was working other aircraft and even a departure off of ZZZ. Aircraft X called on about 20nm south of ZZZ saying that he was losing airspeed and altitude. I advised him that the MEA was 2900. (The supervisor at this time got me a D-Side.) I read him the weather at ZZZ. ZZZ was the closest airport for Aircraft X. I called ZZZ TWR and asked him for the information around the airport. Tower said that the airport was clear to the northwest. Aircraft X was descending below 2900 and climbing back up. He was flying westbound when had cleared him northbound to ZZZ. At one point Aircraft X was down to 2100 and then I saw his Mode C read 3200. I advised Aircraft X that the closest aircraft to him was an aircraft at FL200. I told Aircraft X to do what he needed to do; meaning that if he needed to climb that it would be approved. I should have then reiterated the MEA was 2900. Aircraft X finally was able to fly to the airport. I gave him the weather again and told him that tower said it was clear to the northwest. Tower approved for me to keep Aircraft X coming in. Aircraft X finally got the airport in sight and I cleared him for Visual Approach to RWY 3 at ZZZ. I switched him to Tower and Tower called when he landed safely. Recommendation; when I told Aircraft X to do what he needed to do; I should have told him that he may climb to any altitude he needs. I could have assigned him a block altitude. What I needed to make sure he understood was that at all times the minimum safe altitude was 2900. I should have asked for a D-Side when Aircraft X was picking up ice because it took me some time to enter the PIREP.

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.