Enroute controller described a below mia event when IFR traffic encountered icing and initiated a de...

Narrative:

I was working the radar position on sector X. I had precipitation displayed west of the departure airport; but not along the route the C172 as traveling. The C172 was en route from their departure airport direct to their destination at 100 in an area with a 099 mia (minimum IFR altitude). The C172 declared he was in icing conditions and needed to descend. I stood up from my chair to check the MOCA (minimum obstruction clearance altitude) the airway the C172 was over-flying. I made the decision to turn the aircraft 30 degrees to the right which would direct the aircraft to an area with a 072 mia. I began to issue the clearance when I noticed the MSAW (minimum safe altitude warning) alert flashing. I issued a low altitude alert as well as a 30 degree turn to the aircraft. The C172 was descending without clearance so I restated the mia altitude and told the aircraft to maintain FL100. Soon after the aircraft entered the area with the 072 mia he advised he was returning to his departure airport and canceled IFR. The weather that is displayed should be updated more often and needs to be more accurate. If the precipitation was displayed I could have issued it to the pilot and issued a heading around the area.

Original NASA ASRS Text

Title: Enroute Controller described a below MIA event when IFR traffic encountered icing and initiated a descent below the MIA; the reporter noting improved weather information may have provided a heads-up on the existing condition.

Narrative: I was working the RADAR position on Sector X. I had precipitation displayed west of the departure airport; but not along the route the C172 as traveling. The C172 was en route from their departure airport direct to their destination at 100 in an area with a 099 MIA (Minimum IFR Altitude). The C172 declared he was in icing conditions and needed to descend. I stood up from my chair to check the MOCA (Minimum Obstruction Clearance Altitude) the airway the C172 was over-flying. I made the decision to turn the aircraft 30 degrees to the right which would direct the aircraft to an area with a 072 MIA. I began to issue the clearance when I noticed the MSAW (Minimum Safe Altitude Warning) alert flashing. I issued a Low Altitude Alert as well as a 30 degree turn to the aircraft. The C172 was descending without clearance so I restated the MIA altitude and told the aircraft to maintain FL100. Soon after the aircraft entered the area with the 072 MIA he advised he was returning to his departure airport and canceled IFR. The weather that is displayed should be updated more often and needs to be more accurate. If the precipitation was displayed I could have issued it to the pilot and issued a heading around the area.

Data retrieved from NASA's ASRS site as of July 2013 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	1007323
Time
Date	201204
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Aircraft 1
Make Model Name	Skyhawk 172/Cutlass 172
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT

Enroute controller described a below mia event when IFR traffic encountered icing and initiated a descent below the mia; the reporter noting improved weather information may have provided a heads-up on the existing condition.