Small Aircraft; High Wing; 1 Eng; Retractable Gear
Air Traffic Control Fully Certified
Confusion; Situational Awareness; Communication Breakdown
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Separated Traffic; Air Traffic Control Provided Assistance; Flight Crew Became Reoriented
Weather; Airspace Structure; Human Factors
I was working Departure East with very light traffic. I released Aircraft X from BFI in IMC weather. Aircraft X called on his departure and was squawking the wrong code. I climbed Aircraft X to 040 and issued the correct beacon code. BFI called to coordinate the departure on the improper beacon code; which I answered to roger. Once I got off the line with BFI I immediately noticed that Aircraft X appeared to be tracking on a SSW heading toward SEA with aircraft descending on final. I issued an instruction to Aircraft X to fly heading 130 immediately. I shouted across the room for Final to watch Aircraft X and that I'm turning him. I then instructed Aircraft X to fly heading 090 immediately. Aircraft X came in close proximity to Aircraft Y descending on final approach into SEA who was by then already switched to SEA Tower. When the event was over; I asked Aircraft X what happened with their turn; to which they responded that they were disoriented in the IMC. I asked Aircraft X to report above the cloud layer; and after they did; I issued the statement.I'm really not sure what could have been done differently from an ATC perspective. I should have immediately contacted LC-W at SEA after I gave the turn away from the airport to warn the controller talking to Aircraft Y on final. My phraseology was also rushed and not standard.
S46 TRACON Controller reported a departing aircraft failed to turn to an assigned heading after became disoriented in IMC; resulting in an airborne conflict with another aircraft.