Narrative:

I split off sector 10 to work the lmt fighter aircraft into juniper and goose airspace. One of the aircraft already in the sector was aircraft X. He was already a bit abnormal because he had requested 11;500 feet as an IFR altitude from the previous controller who assigned him block 11;000 to 12;000 feet instead. He was on a route to miss the goose airspace and called to say he had encountered moderate rime icing and needed to get lower. I gave him the lowest altitude I could (10;200 feet). He then asked for vectors to get back to the north and I gave him the best heading I could in the area. I observed him descend below 10;200 ft. And I told him I showed him low and asked him if he was still showing level 10;200 feet. He replied that he was unable to maintain that altitude but had continued to descend and was below the clouds with ground contact. Instead of issuing a low altitude alert; I began advising him of what all of the obstructions in his area were and what the nearest airport. It was not a conscious decision not to issue the alert; I just did what I thought was best for the aircraft at the time. He had made it clear that he was unable to maintain his altitude and I let him know what was out there for him. In hindsight; I still believe this was the right call because if he had been issued the low altitude alert; he likely would have panicked and attempted to climb and been right back in the moderate rime icing he reported. In his descent; he was able to get clear of the clouds; below the icing level and cancel IFR to proceed on to ZZZ. He was also in an area that has very poor radio coverage so each transmission was crucial. I wanted him to have all of the information about the surrounding terrain.he landed safely. I understand what the book says to do in this situation and I am fully aware that I will probably get a record of conference for not issuing the alert.this was unavoidable.

Related reports:

Google
 

Original NASA ASRS Text

Title: ZSE Center Controller reported an aircraft was forced to descend below MVA to escape icing conditions.

Narrative: I split off sector 10 to work the LMT fighter aircraft into Juniper and Goose airspace. One of the aircraft already in the sector was Aircraft X. He was already a bit abnormal because he had requested 11;500 feet as an IFR altitude from the previous controller who assigned him block 11;000 to 12;000 feet instead. He was on a route to miss the Goose airspace and called to say he had encountered moderate rime icing and needed to get lower. I gave him the lowest altitude I could (10;200 feet). He then asked for vectors to get back to the north and I gave him the best heading I could in the area. I observed him descend below 10;200 ft. and I told him I showed him low and asked him if he was still showing level 10;200 feet. He replied that he was unable to maintain that altitude but had continued to descend and was below the clouds with ground contact. Instead of issuing a low altitude alert; I began advising him of what all of the obstructions in his area were and what the nearest airport. It was not a conscious decision not to issue the alert; I just did what I thought was best for the aircraft at the time. He had made it clear that he was unable to maintain his altitude and I let him know what was out there for him. In hindsight; I still believe this was the right call because if he had been issued the low altitude alert; he likely would have panicked and attempted to climb and been right back in the moderate rime icing he reported. In his descent; he was able to get clear of the clouds; below the icing level and cancel IFR to proceed on to ZZZ. He was also in an area that has very poor radio coverage so each transmission was crucial. I wanted him to have all of the information about the surrounding terrain.He landed safely. I understand what the book says to do in this situation and I am fully aware that I will probably get a Record of Conference for not issuing the alert.This was unavoidable.

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.