Small Aircraft; High Wing; 1 Eng; Fixed Gear
Air Traffic Control Fully Certified
Situational Awareness; Human-Machine Interface; Communication Breakdown
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; General Police / Security Involved
Human Factors; Procedure; Chart Or Publication; Airport; Aircraft
Aircraft X checked in on frequency IFR to FCH direct CZQ VOR at 5;000 feet. I asked Aircraft X to say approach request (weather was IFR with low ceilings) and advise when they had FCH AWOS weather. Aircraft X told me they wanted GPS Runway 12 Approach and would advise me when they had the weather. Aircraft X informed me FCH AWOS appeared to be out of service; but they had FAT ATIS information. I clarified that they had the most up-to-date ATIS code and they confirmed. I then descended Aircraft X to 3000 feet and cleared the aircraft direct SIPZY intersection (a fix more than 3 miles from the FAF on the final approach course) with less than a 30 degree intercept to the final approach course. Aircraft X took the instructions however a bit of time passed and I noticed the aircraft appeared to not be turning. I asked the aircraft if they were in the right turn to SIPZY and the pilot came back saying they were having some problems putting it in their GPS. I clarified the spelling again and gave them a heading 120 when able direct SIPZY. I then later went back and asked the pilot if they were able to program the approach and direct SIPZY at that time which they confirmed they had the approach in and then I descended them to 2000 feet. I then gave them their distance from SIPZY (around 6 miles) and to cross at 2000 feet and cleared GPS 12 approach. I coordinated with the next sector to have them cancel IFR on the next sector frequency which is a ground antenna at that airport. I advised Aircraft X to report cancellation of IFR or missed approach on 119.0 and to change to advisory frequency (this was approximately over SIPZY inbound). I then continued working other aircraft and then scanned back to see Aircraft X at approx. 1100 feet a half mile from EWNEL. I did a double take at the altitude to make sure I saw it properly and then tried to pull up the approach plate on to confirm the Minimum Descent Altitude(MDA) which turned out to be 1900 feet. At the same time as I was scrambling to confirm the altitude I was yelling it out so the next controller could also see it as the aircraft was already on their tag since they serve that satellite airport. By the time we could do a blanket broadcast of a Low Altitude Alert just in case they were still monitoring our frequency the aircraft was inside EWNEL and in compliance with MDA. No Low Altitude Alert went off on our system to alert us. Our Minimum Vectoring Altitude in the area is 2000 feet; the MDA for that portion of the IAP is 1900 feet and I observed them at approximately 1100 feet. To make matters worse the pilot never cancelled IFR after we lost Radar Contact with it. Due to my feelings the pilot may have been behind the airplane with the other complications I had experienced; within 7 minutes of losing radar and not receiving a cancellation; I as Controller in Charge (CIC) had called law enforcement so they could search for the aircraft. An ALNOT (Alert Notice) was started approximately 25 minutes after not hearing back from either law enforcement or the aircraft and Center was able to contact the pilot through the flight school. Low Altitude Alert system needs to be configured properly in our airspace. We recently added all of our final approach courses for all IAP's in our airspace (we did not have them before). I am not exactly sure how it works but if they can add the parameters to cause the 'LA' to go off along each final approach course to help alert us if we do not notice the irregularly it can definitely help. Even if I had changed the aircraft to advisory; if I had noticed it earlier I would have also done a broadcast across UNICOM frequency using our standby radio in every effort to ensure safety.
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Two FAT TRACON controllers reported an aircraft on approach that already switched to advisory frequency and descended below the minimum altitudes. The aircraft failed to cancel IFR with ATC.