Date: 201508
Local time of day: 1801-2400
Location: GEG.Airport, WA
Flight conditions: VMC
Light: Night
Aircraft: Medium Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class C GEG
ATC / advisory: TRACON GEG
Aircraft component: Autopilot
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Situational Awareness
Anomaly: ATC Issue All Types; Inflight Event / Encounter Unstabilized Approach
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Executed Go Around / Missed Approach; Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Arriving at GEG; the ATIS was Bravo; Calm wind; 10sm; Few 12000; 27/5; 2994; Visual runway 21. Since we were filed direct to GEG direct GEG airport; I asked the FO if he would like to request runway 3 for arrival since the wind was calm; there is terrain in the area; it was a night approach; and a straight in visual backed up with an ILS was (in my opinion) the safest course of action. He thought that was a good idea; and we briefed it; including the notes on the CCI page referencing visual approaches to GEG at night. I asked Seattle Center if they could call ahead and request runway 3 for us; and the controller said we'd have plenty of time to request that with approach. We contacted Spokane Approach; made the request; and it was granted; and they requested to keep max forward speed as long as possible. We commenced the approach and around the time we should have joined the localizer; the autopilot grabbed a localizer and a glideslope; and the aircraft pitched and rolled a bit. I thought perhaps it was just a 'tough' capture; but it became clear that we had captured something other than the proper navigational signals. At this point; we got behind on configuring while trying to figure out what the aircraft was doing; the FO (PF) disconnected the AP and started hand flying; but we had drifted high and weren't in position to make a stabilized approach; so I called a go around. That went fine; we ran a climb; descent; and approach check; and took vectors for another visual to runway 3. this time the exact same thing happened (and this time much more aggressively - the aircraft pitched up and climbed probably 300-400 feet and banked back and forth a couple times); and I was pretty confused about why; but we were way ahead of the aircraft and properly configured; so the FO (PF) again disconnected the AP and hand flew the approach. Shortly after that; I heard Spokane Approach tell an arrival that they 'had just switched the localizer around.' On the ground; I looked at the approaches to runways 3 and 21; and noticed that they have the same frequency (111.1) but different identifiers (IOLJ & IGEG). It was then obvious what had happened.




Synopsis: On a night visual approach to Runway 3 at GEG; the crew was confused by the erratic localizer and glideslope indications which was attributed to the 'switching around' of the localizer.