Narrative:

I was working the radar position of sector 41. I also had sector 27 at that position which was an unusual combination. Sector 41 normally goes to sector 27 when combined but they were working on the equipment so they combined it up. This couldn't have been at a worse part of the day. Cougar MOA/atcaa was hot in sector 27; weather was building in sector 41; arrivals were coming in to den. Lots of departures were departing out of den; cos; and publication all at the same time with challenging overtakes and unusual situations from all three departure positions.a military flight wanted to break up and we could not hear what they were requesting because of bad radios and frequency congestion. There was also no flight plan for the other aircraft. During this time the fighter jets wanted to return to base out of the cougar MOA and the den arrivals starting picking up. During the military flight breakup; aircraft X; who was landing ank; about 30 miles or so in to sector 12s airspace; kept asking for lower. I descended him to 17000 feet and handed him off to sector 12. I told my radar assist to give them control. He got to 17000 feet and kept asking for lower.many aircraft were stepping on each other while I was trying to do the flight breakup. Sector 12 had still not taken the handoff. I descended the aircraft to 15000 feet and he read it back. This clearance took him below the minimum IFR altitude. My radar assist told me to stop him at 16000 feet and I did when the aircraft mode C was indicating 16300 feet. Aircraft X read back 'one six thousand five hotel wiskey'. During this readback; the training team was plugged in monitoring so we had 4 sets of ears and we all heard the readback. When I went to ship aircraft Y to sector 12 I noticed he was at 15000 feet. I climbed him to 16000 feet and shipped him to sector 12.that sector should not have been combined. Period.

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Original NASA ASRS Text

Title: ZDV ARTCC Controller working combined sectors did not notice an aircraft descended below their assigned altitude below the minimum IFR altitude.

Narrative: I was working the Radar Position of Sector 41. I also had Sector 27 at that position which was an unusual combination. Sector 41 normally goes to Sector 27 when combined but they were working on the equipment so they combined it up. This couldn't have been at a worse part of the day. Cougar MOA/ATCAA was hot in Sector 27; weather was building in Sector 41; arrivals were coming in to DEN. Lots of departures were departing out of DEN; COS; and PUB all at the same time with challenging overtakes and unusual situations from all three departure positions.A military flight wanted to break up and we could not hear what they were requesting because of bad radios and frequency congestion. There was also no flight plan for the other aircraft. During this time the fighter jets wanted to return to base out of the Cougar MOA and the DEN arrivals starting picking up. During the military flight breakup; Aircraft X; who was landing ANK; about 30 miles or so in to Sector 12s airspace; kept asking for lower. I descended him to 17000 feet and handed him off to Sector 12. I told my Radar Assist to give them control. He got to 17000 feet and kept asking for lower.Many aircraft were stepping on each other while I was trying to do the flight breakup. Sector 12 had still not taken the handoff. I descended the aircraft to 15000 feet and he read it back. This clearance took him below the Minimum IFR Altitude. My Radar Assist told me to stop him at 16000 feet and I did when the aircraft Mode C was indicating 16300 feet. Aircraft X read back 'One Six Thousand Five Hotel Wiskey'. During this readback; the training team was plugged in monitoring so we had 4 sets of ears and we all heard the readback. When I went to ship Aircraft Y to Sector 12 I noticed he was at 15000 feet. I climbed him to 16000 feet and shipped him to Sector 12.That sector should not have been combined. Period.

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.