Commercial Fixed Wing
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 6
Situational Awareness; Communication Breakdown
ATC Issue All Types; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert
Procedure; Human Factors; Airspace Structure
I was working and had just arrived to start my shift. I had been working the sector less than 10 minutes when I cleared Aircraft X to cross ZZZ at or above 14;000 ft. and issued an approach clearance for the ILS approach. The pilot read back a crossing restriction of 11;000 ft.; which I did not catch. I was relieved from the position for a break; and after leaving the control room I was told that [the flight] had descended below the MIA (Minimum IFR Altitude) prior to reaching ZZZ and was issued a low altitude alert. I do not have any recommendations.
A Center Controller reported a flight crew descended below the minimum IFR altitude after he missed the crews incorrect read back of the assigned altitude.