Narrative:

I was about to begin ojti with my trainee at D38. Sectors 27 and 38 were still combined and my trainee does not have a training plan for sector 27 so we were waiting for the r-side to brief another controller who was opening/splitting off sector 27. Aircraft X was [flying from] ZZZ1 direct to ZZZ2 and level at his requested final of FL250. Aircraft X would only be in sector 38 briefly as he was cutting the southwest corner of the sector. He was a 'flash through' between ZMP sector 39 and ZKC sector 26 and should have still been on sector 39's frequency. During the sector-split briefing the r-side noticed that aircraft X had begun descending rapidly despite the data block reflecting an assigned altitude of FL250. R38 queried R39 about the descent. R39 attempted to contact aircraft X multiple times unsuccessfully. R38 attempted to contact him as well on sec 38 and 27's frequencies as well as 121.5. Aircraft X was on the ZMP/ZKC boundary at this point and his descent was creating the need for multiple point-outs and coordination. I excused my trainee and sat down at D27/38 and began coordinating and making point-outs without a briefing because time was of the essence. I had a good overview of the sectors and situation already because I had been standing there for several minutes watching and waiting to begin ojti. I pointed him out to ZKC sectors 26 and 44. I alerted both sectors to the unexpected descent and advised them that aircraft X was not in contact with ATC. ZMP sector 26 called and said that aircraft X had contacted them and declared an [urgent situation]. The pilot must have gone to this frequency on his own after finding it on a chart; map; or other cockpit resource. ZMP sector 26 is the pawnee city low sector and had no reason to know who this aircraft was. ZMP sector 26 eventually figured out who it was and contacted me at sector 38. I requested communications of aircraft X but I suppose the pilot was too busy and/or did not want any frequency changes. Aircraft X stated he had lost an engine and intended to land at ZZZ3. The pilot would eventually correct himself and state that he was landing at ZZZ4. A military aircraft that was on frequency was able to go to the unicom frequency and confirm that aircraft X landed safely. Additionally; supervisors from either ZMP or ZKC were able to contact the FBO at ZZZ4 as well as the local sheriff's dept. To go check on aircraft X.obviously the engine failure was not preventable. I thought the situation was handled extremely well and everything possible was done to assist aircraft X. All sectors nearby ZZZ4 have poor radio coverage. We eventually lost the ability to communicate with [the aircraft] when he descended through 7;000 MSL. Terrain is generally not an issue in this area so an infusion of funds into the radio infrastructure in the surrounding area would be helpful. Radio coverage is a huge issue throughout all/most ZMP low altitude sectors as well as some high sectors. Additionally; the pilot's decision to change frequencies on his own was not helpful. I'm sure he had a reason and panic played a role but it created confusion and impeded our ability to assist him.

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Original NASA ASRS Text

Title: Multiple ZMP Center controllers reported a small aircraft descended without communicating with ATC following an engine failure.

Narrative: I was about to begin OJTI with my trainee at D38. Sectors 27 and 38 were still combined and my trainee does not have a training plan for Sector 27 so we were waiting for the R-side to brief another controller who was opening/splitting off Sector 27. Aircraft X was [flying from] ZZZ1 direct to ZZZ2 and level at his requested final of FL250. Aircraft X would only be in Sector 38 briefly as he was cutting the southwest corner of the sector. He was a 'flash through' between ZMP Sector 39 and ZKC Sector 26 and should have still been on Sector 39's frequency. During the sector-split briefing the R-Side noticed that Aircraft X had begun descending rapidly despite the data block reflecting an assigned altitude of FL250. R38 queried R39 about the descent. R39 attempted to contact Aircraft X multiple times unsuccessfully. R38 attempted to contact him as well on Sec 38 and 27's frequencies as well as 121.5. Aircraft X was on the ZMP/ZKC boundary at this point and his descent was creating the need for multiple point-outs and coordination. I excused my trainee and sat down at D27/38 and began coordinating and making point-outs without a briefing because time was of the essence. I had a good overview of the sectors and situation already because I had been standing there for several minutes watching and waiting to begin OJTI. I pointed him out to ZKC sectors 26 and 44. I alerted both sectors to the unexpected descent and advised them that Aircraft X was not in contact with ATC. ZMP Sector 26 called and said that Aircraft X had contacted them and declared an [urgent situation]. The pilot must have gone to this frequency on his own after finding it on a chart; map; or other cockpit resource. ZMP Sector 26 is the Pawnee City Low sector and had no reason to know who this aircraft was. ZMP Sector 26 eventually figured out who it was and contacted me at Sector 38. I requested communications of Aircraft X but I suppose the pilot was too busy and/or did not want any frequency changes. Aircraft X stated he had lost an engine and intended to land at ZZZ3. The pilot would eventually correct himself and state that he was landing at ZZZ4. A military aircraft that was on frequency was able to go to the UNICOM frequency and confirm that Aircraft X landed safely. Additionally; supervisors from either ZMP or ZKC were able to contact the FBO at ZZZ4 as well as the local Sheriff's Dept. to go check on Aircraft X.Obviously the engine failure was not preventable. I thought the situation was handled extremely well and everything possible was done to assist Aircraft X. All sectors nearby ZZZ4 have poor radio coverage. We eventually lost the ability to communicate with [the aircraft] when he descended through 7;000 MSL. Terrain is generally not an issue in this area so an infusion of funds into the radio infrastructure in the surrounding area would be helpful. Radio coverage is a huge issue throughout all/most ZMP low altitude sectors as well as some high sectors. Additionally; the pilot's decision to change frequencies on his own was not helpful. I'm sure he had a reason and panic played a role but it created confusion and impeded our ability to assist him.

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.