Date: 201909
Local time of day: 0001-0600
Location: BOI.TRACON, ID
Light: Night
Aircraft: DA40 Diamond Star
Flight plan: IFR
Flight phase: Descent
Airspace: Class E BOI
ATC / advisory: TRACON BOI
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance
Contributing factors: Airspace Structure; Human Factors
Primary problem: Human Factors

Narrative: I issued a descent for an aircraft on an airway which I believed cleared a higher MVA but turns out it wouldn't so I fixed it. Here's what led to the event: Aircraft X was arriving Bozeman (BZN) from the east. I took the hand-off from ZLC. The aircraft was at 10;000 feet; which was okay for the portion of his routing (V86) as far as Livingston (LVM) VOR. Beyond that; the MEA on V86 is 10;900 feet; so once Aircraft X was within my lateral boundary; I climbed him to 11;000 feet.At 11;000 feet. I couldn't keep radar contact on him so I asked for position reports over LVM and ZUBLI. I had no other traffic and he was pegged down to the airway so I was not overly concerned about poor radar reception. Prior to ZUBLI; I re-established radar contact with Aircraft X; at which time he requested the VOR Runway 12 approach into Bozeman. I thought to myself; 'This will be slick! He's already on an airway that takes him to the VOR and sets him up great for the approach. All I have to do is step him down.' I brought up my map for the VOR approach. In doing so; the STARS map for the VOR Runway 12 approach also depicts RNAV A Approach way points ZIPGO and SUBKY. On my scope; ZIPGO is indicated with the way point symbol and 'ZI.' ZIPGO is about 2 NM west of ZUBLI; which is indicated on the STARS display with a delta symbol and 'ZB.''ZB' is where V86 makes a turn to the northwest to the BZN VOR. In my tired; mid-shift state; with only this one aircraft; I envisioned V86 going over the 'ZI' symbol versus the 'ZB' symbol. In doing so; I directed Aircraft X to descend to 9;000 feet after ZUBLI; which he read back correctly and complied with. I envisioned V86 remaining entirely within my 9;000 foot MVA and thought I was golden. That's when reality bit me. Aircraft X made the northwest bound turn alright; and was about 2 miles east of where I expected him to be; heading towards an 11;000 foot MVA. I quickly brought up my airway map and saw that sure as [expletive]; he was on the airway which did not clear the 11;000 foot MVA so I immediately issued a left turn heading 2-5-0 for Aircraft X and asked him to expedite the turn; explaining it was turns for terrain and lower MVA's for the approach. Aircraft X was a mile or two from the 11;000 foot MVA tracking H290 on the BZN 110 Radial; at about 10;200 feet when he made the turn.Aircraft X made the turn prior to entering the 11;000 foot MVA but it was [expletive] close. On the large 60 nm range we have to watch to take handoffs from ZLC prior to our boundary; it is difficult to see if the digitized target remained entirely clear of the MVA line or encroached upon it. I don't know if this triggered a 'snitch' [alarm] or not.I would rather the VOR Runway 12 approach map not include way points for the RNAV GPS-A Approach into BZN. This was 100% what bit me. Without that waypoint standing fat and happy in the middle of my 9;000 ft. MVA; I'd have re-evaluated where and when to descend Aircraft X. Yes; I understand the difference between a waypoint; its associated symbol and fix on an airway as well as its associated symbol. In my rush to judgment; I simply tuned out the 'ZB' and saw 'ZI' where I wanted Aircraft X to turn and thought that was ZUBLI. Oops.I would rather we not have two very similar looking ['ZI' vs 'ZB'] way points; with similar names [ZIPGO and ZUBLI] depicted so close together.Our base map always has ZUBLI depicted on there. Maybe 2 planes a year that I talk to actually fly V86. Running the airway map is not something I do; and ZUBLI is not something I routinely notice in my active scan. Fortunately; the airway map is one quick button push away on our STARS panel (Button 6) when needed. Had I been running that airway map; I'd have noticed the dots depicting the airway turn at 'ZB' vs 'ZI' and also the fact that the airway drags across the southern edge of an 11;000 foot MVA. The airway dots and MVA contour line are co-located there. There's no way the airway laterally misses that MVA.Lesson learned. I will strive to remain more vigilant; especially when tired on the mid with only one aircraft. I'll try to realize I'm tired; and ensure my instructions are correct. I've never run a VOR approach from V86 inbound from the East and I thought this would be a slick operation. Boy; did I set myself up for failure.




Synopsis: Boise TRACON Controller reported descending an aircraft below the Minimum Vectoring Altitude.