Date: 202009
Local time of day: 1801-2400
Location: ZSE.ARTCC, WA
Light: Daylight
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Descent
Airspace: Class E ZSE
ATC / advisory: Center ZSE
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Training / Qualification; Confusion
Second reporter function: Enroute
Anomaly: ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; 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 Advisory / Alert; Air Traffic Control Issued New Clearance
Contributing factors: Company Policy; Airspace Structure; Chart Or Publication; Procedure; Human Factors
Primary problem: Procedure

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.


Second narrative: I was assisting another controller in the area when a TMC (Traffic Management Coordinator) walked by the area and asked if I was a pilot and had time for a question in the adjacent area. I immediately went to the indicated sector and the controller working explained to me that they had cleared an aircraft for approach via an airway and was wondering why the aircraft had descended to 1;600 feet. After reviewing the approach plate and assessing the situation; I realized that aircraft had descended below the appropriate MEA (Minimum Enroute Altitude and I immediately instructed the controller to climb the aircraft and give them a low altitude alert. Additionally; I instructed the controller to give the aircraft the Brasher statement. The adjacent area only has one airport which they provide approach control services for. In my opinion; most controllers lack familiarity with approach procedures and nuisances associated with them. I believe that is a primary contributing factor as to why a delayed climb and low altitude alert was issued. Additional refresher training for controllers in the area to reiterate approach clearance procedures. A possible change to the 7110.65 to require that an altitude to maintain is given even if the aircraft if on an established airway.


Synopsis: 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.