Caravan Undifferentiated
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 5
Communication Breakdown; Confusion; Distraction; Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Human Factors; Airspace Structure; Procedure
Aircraft X was level at 110 in a 120 Minimum IFR Altitude (MIA) en-route to FMN. I didn't realize that Aircraft X was below the MIA until it was in my airspace for a couple minutes. ZAB started the hand off about 10 miles south of my airspace and I believe the aircraft was in a 112 MIA when they started the hand off. The MIA changes from 112 to 120 at the ZDV/ZAB boundary. Minimum Safe Altitude Warning (MSAW) was not flashing and I didn't realize the aircraft was about to enter a 120 MIA.Aircraft X didn't check on freq until about 1 mile into my airspace. A minute or two later; I realized he was below the MIA. I asked if he has good visual with the terrain and if he could maintain his own terrain and obstruction clearance for the next four minutes. The pilot responded affirmative to both. Based on the weather conditions; the aircraft performance; and the proximity to lower MIA; I didn't feel it was necessary to climb the aircraft. About 1 minute later; MSAW started flashing. A few minutes later; Aircraft X entered a 100 MIA.No specific recommendations. I'm curious as to why MSAW didn't alert until the aircraft was halfway through the 120 MIA. It was a strong reminder to me not to rely solely on automation. The ZAB controller and I need to stay diligent in paying close attention to routes of low altitude aircraft in reference to MIA's. ZAB shouldn't have handed me the aircraft at 110; but I should have recognized it earlier and called them to climb the aircraft.
ZDV Controller reported receiving an aircraft below the Minimum IFR Altitude.