Commercial Fixed Wing
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 5
Distraction; Human-Machine Interface; Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Ground Event / Encounter Ground Equipment Issue; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance
Chart Or Publication; Software and Automation; Procedure; Human Factors
Aircraft X checked on from the East and requested the RNAV Approach. I cleared them for the approach over HILIE at 8;000 feet and they read the instructions back correctly. I had the approach plate pulled up initially on the Information Display System (IDS) to verify that 8;000 feet was an appropriate crossing altitude but then toggled back to the normal IDS screen; to keep an eye on the weather. As they got further along on the approach; I noticed the aircraft was at 6;400 feet inside of the 6;500 foot Minimum Vectoring Altitude (MVA).  Unfortunately; I didn't review that section of the approach during their check on and it didn't set an alarm bell off in my head because we do have approaches in our airspace that have published altitudes below our MVAs. I quickly pulled up the approach plate on the IDS to double check.When I started comparing the approach plate and the radar overlay of the approach; I initially thought they were between NAXAF and CUGEV; not outside of CUGEV.  If you look at the approach plate on the IDS; going from the runway out the fixes are: WIVUP; NAXAF; CUGEV; and OZOLA. However; the RNAV Y 26 approach that is available on the radar display is missing the fix 'WIVUP;' so going from the runway out on the radar displayed map you have: NAXAF; CUGEV; and OZOLA).  I then asked the pilot if they were outside of CUGEV and they responded 'Yes'.  I realized they were descending way too early and I issued a safety alert to climb to 6;700 feet. After they climbed; I asked what their intentions were and they wanted the Visual Approach. I cleared them for the Visual Approach.I was not pleased with my recovery time and felt like I should have reacted quicker. We are very rarely on a Runway XX flow and I should have reviewed the radar display map; approach plates; and appropriate altitudes in more detail before and while on position.  I should have just gone with my gut feeling and immediately issued the Low Altitude Alert and asked questions afterwards.  The Low Altitude Alert never triggered which seems like a common theme in these situations. It would be really nice if we could somehow make that thing more accurate.  I think that the fix 'WIVUP' should be added to the radar displayed map so that is correlates exactly with the approach plate. I think it would have helped me recognize more quickly where the aircraft was on the approach and that they were low.My phraseology was not perfect with the low altitude alert but I really think the phraseology needs to rewritten. By the time I got to the 'advise you climb and maintain part' it seemed like they had descended almost another 200.' That small amount of time could be the difference between impacting terrain and not. Maybe something like 'Aircraft X advise you climb and maintain 6;700 immediately; Low Altitude Alert the appropriate altitude for your area of flight is 6;700' I think getting the aircraft climbing quickly should be the absolute priority and in a situation like this.
GEG TRACON Controller reported they issued a clearance that placed an aircraft below the Minimum Vectoring Altitude. The Controller's radar map was inaccurate and the Low Altitude Alert did not function.