Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 28
Situational Awareness; Training / Qualification
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Provided Assistance
Procedure
Aircraft X requested the ILS Z 12 approach into EAT. Since he was established on the airway (V120); and the IAF (WINIM) was on the radial that made V120; I simply told Aircraft X 'cleared for approach'. A couple of minutes later; Aircraft X requested lower altitude. I explained to him that since he was on an airway; he automatically had clearance to descend to the MEA until he was established on a published segment of the approach procedure; then he could continue his descent. My D-side and I observed Aircraft X descending to the MEA (120); and continue to descend. I told Aircraft X to check his altitude; since he was below the MEA and approaching the MOCA. I instructed Aircraft X to climb to 120 until he had progressed WINIM. He was continuing to descend; so issued a Low Altitude Alert; advising him that the MIA was 112; and that he had to check his altitude and climb immediately. Aircraft X advised that he was climbing back to 120; where he remained until progressing WINIM and commencing the ILS approach. I noted that a second voice came on the frequency after the trouble started; and this made me wonder if there was a student pilot on board.In the last few years; I have noted several instances where pilots do not seem to realize that 'cleared for approach' gives them clearance to descend to the MEA of the route segment that they are currently flying (or the 'floor' if they're in a TAA). They seem to have become conditioned to expect assignment of a crossing altitude at the IAF; regardless of whether they are established on a route segment or direct the IAF. I wonder if with GPS's; which navigate to fixes; modern pilots are 'fix fixated'; that is; they don't pay attention to MEAs; as more and more pilots fly direct to fixes rather than Victor airways. This could explain why they seem to be at a loss as to when they can descend; and what altitude they can descend to; when given a simple 'cleared for approach' clearance that has no crossing restriction associated with it.I would suggest some communication to pilots and flight schools to give pilots a refresher on this issue. I do not think we should require controllers to assign crossing restrictions over IAFs regardless of whether the aircraft is navigating direct the IAF or an airway; this would constitute an unacceptable 'dumbing down' of the system. Modern cockpit automation is making flying an easier task; but I do think it's also making pilots a bit complacent and deficient in basic skills.
ZSE controller reports of an aircraft that is cleared for an approach but descends below the MEA.