Caravan Undifferentiated
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 4
Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport
Weather
Aircraft X departed JNU for ZZZ; but changed destination shortly after to return to JNU because the pilot reported that ZZZ winds would not allow for an approach. Aircraft X initially climbed to 090; but requested descent to 080 for moderate icing. I cleared Aircraft X back to the JNU airport via direct SSR direct; to expect the LDA Z 8 approach; as requested.I cleared Aircraft X for the LDA Z 8 approach; to cross SSR at or above 060. Shortly after progressing SSR; the aircraft transmitted that they were back in the icing and had 'quite a bit of ice on the wing' and said they were unsure if they would be able to maintain the transition altitude of 056 until LYNNS intersection. The aircraft then descended to 052; below the approach altitude. I issued a low altitude alert; and instructed Aircraft X to climb to meet the transition altitude. Aircraft X reported they would attempt to climb; but were unable and appeared to level off at 050 in a 060 MIA (Minimum IFR Altitude); and requested to transition over to the RNAV W 8 approach via JIGMI; as the approach had a lower transition altitude. Seeing as the aircraft had already progress JIGMI; I asked if they would be able to establish themselves on to a published portion of the approach if I provided a heading to join. the pilot said affirmative; so I issued a 10 degree turn to the right to join the RNAV W 8 approach; and to steer the aircraft away form higher terrain to the NW; as it was clear they would be unable to climb. I then informed the pilot that I was providing priority handling for them. Aircraft X was able to maintain 050 until joining the RNAV W 8 approach; at which time I issued the approach clearance and confirmed that the aircraft would be able to maintain the new transition altitudes of that approach. The pilot confirmed that they would; and was able to safely fly the approach to landing.
Anchorage Center Controller reported C208 encountered icing on approach resulted in decent below MIA.