Narrative:

Aircraft X on an IFR flight plan at 6;000 feet. I had one aircraft already on an approach to the airport when I started talking to aircraft X. I issued aircraft X holding over a fix; to hold northeast on the airway with left turns. Part of the read back was stepped on by my other frequency; so I went back and verified left turns. I issued the left turn so I could descend the aircraft and not worry about terrain north of the airway. Shortly after the clearance; I see aircraft X make a right turn. I verified the aircraft was clear of the higher mia (minimum IFR altitude) and told aircraft X they need to hold with left turns.the pilot explained that they were making a tear drop into the holding pattern. I am not quite sure why that would be necessary given the pilot's proximity to the holding fix prior to entering hold. Once the other traffic at was no factor; I cleared aircraft X to the airport via the airway. They wanted the VOR approach with the procedure turn. I cleared them for that approach and told them to report procedure turn inbound. When I looked at the aircraft later; I noticed they were at 1;600 feet about 5 miles northeast of the VOR. The mia on V27 is 3;200 feet and the at or above altitude for the VOR is 1;600 feet. I issued a low altitude alert and a climb. I had something similar happen at this same airport not long ago; but I was able to catch it sooner. Pilots flying IFR flight plans need to understand the procedures. I think this pilot in particular was an instructor pilot which is even more disconcerting.

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Original NASA ASRS Text

Title: Two Center Controllers reported a C172 cleared for an approach to a non towered airport did not follow the procedure and flew below the Minimum Enroute Altitude. One of the Controllers reported a low altitude alert was not issued in a timely manner due to the other controller's lack of proficiency with this situation.

Narrative: Aircraft X on an IFR flight plan at 6;000 feet. I had one aircraft already on an approach to the airport when I started talking to Aircraft X. I issued Aircraft X holding over a fix; to hold NE on the airway with left turns. Part of the read back was stepped on by my other frequency; so I went back and verified left turns. I issued the left turn so I could descend the aircraft and not worry about terrain north of the airway. Shortly after the clearance; I see Aircraft X make a right turn. I verified the aircraft was clear of the higher MIA (Minimum IFR Altitude) and told Aircraft X they need to hold with left turns.The pilot explained that they were making a tear drop into the holding pattern. I am not quite sure why that would be necessary given the pilot's proximity to the holding fix prior to entering hold. Once the other traffic at was no factor; I cleared Aircraft X to the airport via the airway. They wanted the VOR approach with the procedure turn. I cleared them for that approach and told them to report procedure turn inbound. When I looked at the aircraft later; I noticed they were at 1;600 feet about 5 miles northeast of the VOR. The MIA on V27 is 3;200 feet and the at or above altitude for the VOR is 1;600 feet. I issued a low altitude alert and a climb. I had something similar happen at this same airport not long ago; but I was able to catch it sooner. Pilots flying IFR flight plans need to understand the procedures. I think this pilot in particular was an instructor pilot which is even more disconcerting.

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.