Date: 201811
Local time of day: 1801-2400
Location: ZLC.ARTCC, UT
Flight conditions: VMC
Light: Daylight
Aircraft: Citation V/Ultra/Encore (C560)
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Climb; Initial Climb
Airspace: Class E ZLC
ATC / advisory: Center ZLC
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Aircraft; Airspace Structure; Company Policy; Human Factors; Procedure
Primary problem: Airspace Structure

Narrative: I was working when Aircraft X departed. When he came up on my frequency; I radar identified him and told him to climb and maintain FL330. His response was 'hang on; we are gonna stay with you a bit; we are having some problems here.' The airplane was still climbing; but below terrain. I turned out another aircraft who was in the vicinity at a lower altitude to give myself some room in case Aircraft X needed to return. Sure enough; when he was out of 11;000 feet (Minimum IFR Altitude 11;900 feet) he began a turn back towards the airport and informed me they needed to return to land. I asked him if he was VMC and he said he was. I gave him a heading back towards the IAF and climbed him to 14;000 feet. I enquired to the nature of the problem and he told me he was having gear issues. When Aircraft X was at a 90 degree angle to the Initial Approach Fix I cleared him to the fix and told him to cross it at 13;000 feet and that he was cleared for the approach.The aircraft stayed on the heading towards a 13;800 foot Minimum IFR Altitude. Just as I was about to give him a heading; he turned right which was unexpected. I continued to watch him turn thinking that if he kept his right turn tight he would be ok. He then decided to turn to the left plowing further in the higher terrain area. I asked him if he was VMC and notified him of the higher terrain. He said he was VMC and had the terrain in sight. I told him to continue the right turn if he could to keep him from flying even further into the higher terrain. The aircraft crossed the Initial Approach Fix and continued the approach. Due to the fact that the aircraft was in the turn and VMC before asking me for clearance back to the airport; I treated him as a [priority]. Since the aircraft flew in to higher terrain but was VMC and I was not going to climb him I didn't give a low altitude alert.




Synopsis: ZLC Center Controller reported an aircraft did not comply with an assigned clearance to a fix and flew below the Minimum IFR Altitude.