Date: 202009
Local time of day: 1801-2400
Location: ZSE.ARTCC, WA
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Cruise
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; Communication Breakdown; Distraction
Second reporter function: Local
Anomaly: ATC Issue All Types; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural FAR; 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 New Clearance
Contributing factors: Airspace Structure; Chart Or Publication; Human Factors
Primary problem: Airspace Structure

Narrative: [Aircraft X] checked in at 6000 ft. It appeared to be deconflicted. I hadn't noticed it was at an incorrect altitude for said airway. I noticed the aircraft at 6000 feet on the airway. I presumed Approach put him at the correct altitude. At this area on the airway there are no depicted intersections or compulsory reporting points. At 6000 feet he was the right altitude for direction of flight. I moved on to other D Side (Radar Assist) duties. Minutes later the Radar Controller was checking the airway altitudes; MSAW (Minimum Safe Altitude Warning) alert went off and the aircraft was given a climb. At check on 6000 feet was appropriate per the MIA (Minimum IFR Altitude) though not the MEA.Recommend a better vigilance. I would normally check routes and altitudes prior to taking a hand off. I'll incorporate that as an earlier occurrence when on the D side and not presume that approach control gave an appropriate altitude.


Second narrative: I had relieved the other controller. During the briefing; I was told that [Aircraft X] was an IFR overflight at [6000 ft.] and was direct ZZZZZ; when another aircraft had transmitted; interrupting the briefing. After the relieved controller responded to the aircraft; he continued his briefing by moving onto other traffic in the airspace. I took the position; and had multiple aircraft doing practice approaches; an IFR inbound to ZZZ1; and a pop up VFR aircraft requesting flight following for an aerial survey. I checked on the overflight; seeing they were still on course direct ZZZZZ at [6000 ft.]. I then started the handoff to ZSE; and after they accepted the handoff; I transferred communications of [Aircraft X] to [them]; which was right before the MEA increases to 070. The lowest MVA in my airspace where [Aircraft X] was flying was 048 and the portion of [the airway] that increases to 070 only extends about 8 miles in my airspace so I missed seeing the altitude increase for that particular airway. This is also an airway that we don't often see aircraft flying on regularly. Additionally; all of our strips are half strips; so a portion of the number from [the airway] and ZZZ were both cut off from the strip. The controller I relieved wrote ZZZ on the strip but did not rewrite [the airway] and also put ZZZ in the datablock of the aircraft. As the aircraft was not below any of my MVA's; I was not briefed the aircraft would be joining an airway in our airspace; and ZZZ was shown in the data block; without looking at the strip; I thought the aircraft was direct ZZZ rather than on the airway. During the time that this aircraft was in my airspace; I was vectoring and calling traffic to multiple other aircraft so that's why I did not look at the strip when I took over the position.Our strips [should] be printed on full length strips as it cuts off part of the route when only half the strip is used and often times does not get rewritten on the strip.


Synopsis: One TRACON Controller did not realize an aircraft would be below the MEA; while the center controller accepted the handoff with the aircraft below the MEA.