Light Transport
Air Traffic Control Developmental
Communication Breakdown; Situational Awareness
ATC Issue All Types; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Airspace Structure; Chart Or Publication; Human Factors
I was the Radar Controller of the combined sectors. Aircraft X was on a heading at 16;000 feet. I issued a descent to 14;000 feet; the Minimum IFR Altitude (MIA) in his area at the time was 13;700 feet. I thought the read back was correct; however after listening to it; it was very unclear. I noticed the pilot start to descend through 14;000 feet; to 13;700 feet where I asked; 'say altitude'. The pilot came back saying his altitude was 13;500 feet at the time; and descending to 11;000 feet. I issued a low altitude alert and a climb above the MIA.I recommend new radios; or a new radio system.
I was given an initial descent from 16;000 feet inbound to the airport. I read back 11;000 feet twice and the controller had given me 14;000 feet. I looked at the terrain and thought it could be low; but failed to ask the controller if 11;000 feet was the correct altitude. I descended to 13;400 feet and the controller called. I immediately climbed to 14;000 feet.
A pilot and Center Controller reported a communication problem with an altitude clearance and descended below the minimum IFR altitude.