Center controller reported an aircraft experienced icing; stalled; and could not maintain altitude. ...

Narrative:

I took over from the previous controller who didn't build what I considered enough space for the ZZZ1 arrivals. I started vectoring and building space between them. I had a lot of other things going on with most of the aircraft in the sectors needing approach services and help with rides icing. Aircraft X was overflying the zzzzz mountain range and ZZZ2 which is the IAF (initial approach fix) for the active runway at ZZZ1. He was picking up ice so I tried to climb him out of the conditions. He came back and said that he couldn't continue the climb to 17000 ft. And would need to go back down to 15000 ft. He then had said he needed lower and I told him I had opposite direction traffic at 14000 ft. So if he needed lower I would need to turn him to the south. He said okay so I turned him to a 160 heading and gave him 14000 ft. He then said 'I stalled' and I noticed he began a rapid descent. I still had other aircraft and did a quick traffic scan and thought he was in a dive to regain airspeed to pull out of the stall. I thought the most helpful transmission I could give was to tell him what my mia (minimum IFR altitude) in the area was so if he was IMC he would know roughly what altitude he would impact the ground so he could plan his stall recovery dive accordingly. I decided in that moment to say only that and not use radio time/overwhelm him with the low altitude alert. I also wanted to leave the frequency open so he could make any requests like is there a road nearby to crash on or ask for a pilots assistance or recommendations. I thought he had seconds to a minute to live and felt like I needed to leave the frequency open. I also looked around for a topographical map of the ZZZ1 area which has disappeared or our atlas which is hard to locate so if he made a request of where the lowest possible terrain area or roads were. He pulled out of the dive; came back up on frequency; mentioned he didn't want to climb back into the clouds so I instructed him that I couldn't leave home IFR under the mia. I asked if he was VMC; he said yes so I quickly gave him the option of canceling IFR and switching to VFR flight following so he could stay below the clouds and remain clear of ice. He lived.

Original NASA ASRS Text

Title: Center Controller reported an aircraft experienced icing; stalled; and could not maintain altitude. Aircraft recovered below the Minimum IFR Altitude.

Narrative: I took over from the previous controller who didn't build what I considered enough space for the ZZZ1 arrivals. I started vectoring and building space between them. I had a lot of other things going on with most of the aircraft in the sectors needing approach services and help with rides icing. Aircraft X was overflying the ZZZZZ mountain range and ZZZ2 which is the IAF (Initial Approach Fix) for the active runway at ZZZ1. He was picking up ice so I tried to climb him out of the conditions. He came back and said that he couldn't continue the climb to 17000 ft. and would need to go back down to 15000 ft. He then had said he needed lower and I told him I had opposite direction traffic at 14000 ft. so if he needed lower I would need to turn him to the south. He said okay so I turned him to a 160 heading and gave him 14000 ft. He then said 'I stalled' and I noticed he began a rapid descent. I still had other aircraft and did a quick traffic scan and thought he was in a dive to regain airspeed to pull out of the stall. I thought the most helpful transmission I could give was to tell him what my MIA (Minimum IFR Altitude) in the area was so if he was IMC he would know roughly what altitude he would impact the ground so he could plan his stall recovery dive accordingly. I decided in that moment to say only that and not use radio time/overwhelm him with the low altitude alert. I also wanted to leave the frequency open so he could make any requests like is there a road nearby to crash on or ask for a pilots assistance or recommendations. I thought he had seconds to a minute to live and felt like I needed to leave the frequency open. I also looked around for a topographical map of the ZZZ1 area which has disappeared or our atlas which is hard to locate so if he made a request of where the lowest possible terrain area or roads were. He pulled out of the dive; came back up on frequency; mentioned he didn't want to climb back into the clouds so I instructed him that I couldn't leave home IFR under the MIA. I asked if he was VMC; he said yes so I quickly gave him the option of canceling IFR and switching to VFR flight following so he could stay below the clouds and remain clear of ice. He lived.

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.

Attributes
ACN	1766771
Time
Date	202010
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	IMC
Aircraft 1
Make Model Name	Small Aircraft Low Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 11
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Inflight Event / Encounter CFTT / CFIT Inflight Event / Encounter Loss Of Aircraft Control Inflight Event / Encounter Weather / Turbulence

Center controller reported an aircraft experienced icing; stalled; and could not maintain altitude. Aircraft recovered below the minimum IFR altitude.