Small Aircraft; High Wing; 1 Eng; Fixed Gear
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 7
Communication Breakdown; Confusion; Situational Awareness
ATC Issue All Types; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance
Airspace Structure; Human Factors; Chart Or Publication
I had taken over the position about 10 minutes prior and due to the language used during the relief briefing I was led to believe the aircraft was filed on an airway with GPS altitudes allowing for 8000 feet to transit right next to a 9000 foot Minimum IFR Altitude. I saw the aircraft deviating rather far to the south so I turned him to the north even though I thought he was still within the confines of the airway. Shortly thereafter I realized he was actually just filed point to point and was now just inside the 9000 foot MIA at 8000 feet. I then climbed him to 9000 feet. I just need to use more vigilance when taking over a position and make sure I'm clear what is being communicated from the previous controller.
ZSE Center Controller reported they allowed an aircraft to fly below the minimum IFR altitude.