Date: 202101
Local time of day: 1801-2400
Location: S46.TRACON, WA
Flight conditions: Marginal
Light: Daylight
Aircraft: Light Transport
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Climb
Airspace: Class B SEA
ATC / advisory: TRACON S46
Second aircraft: Commercial Fixed Wing
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Human-Machine Interface; Situational Awareness
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Separated Traffic; Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented
Contributing factors: Procedure; Human Factors; Environment - Non Weather Related; Airspace Structure; Chart Or Publication
Primary problem: Airspace Structure

Narrative: I released Aircraft X for departure from BFI in a south flow. Aircraft X reported climbing to 2;000 ft. on the NIRVANA1 SID. I radar identified Aircraft X and climbed them to 6;000 ft.. As Aircraft X was climbing through 1;800 ft. I noticed that Aircraft X appeared to be making a right turn towards the SEA VOR and not following the NIRVANA SID. I instructed Aircraft X to 'turn left immediately; left turn heading 130.' At this point; Aircraft X was starting to converge with Aircraft Y who was on final approach into SEA descending through 1;100 ft. on the ILS Approach to Runway 16R. Aircraft X was about 1.5 miles laterally separated and 700 ft. vertically separated from Aircraft Y and converging. I observed Aircraft X achieve vertical separation from Aircraft Y; then saw the turn to heading 130 start occurring. I gave Aircraft X the Brasher statement. The pilot of Aircraft X stated that it 'looks like the activation for the autopilot for the NIRVANA1 did not take place.'I honestly don't know how to fix this problem; but it is a recurring; systemic issue. This is not my first event with almost identical circumstances; and many of my co-workers have had very similar events. Attempts have already been made to alter the SID; or issue an initial heading for aircraft departing BFI; but these events still occur. The typical issue is that pilots are filing SEA.J5 and though BFI is issuing the NIRVANA1 SID and a Preferred Departure Route that would join J5 from TAOMA or SUMMA; pilot error including unchecked autopilot actions that result in a turn to SEA VOR will immediately cause convergence at the same altitude as aircraft inbound to SEA within the final approach fix; as well as any aircraft departing SEA during that time. There is very little and very subtle warning; and immediate action is necessary to recover separation and end the rapidly worsening danger of the situation. I believe in most cases it is a result of an individualized pilot deviation; and I don't know how to end those completely. The only other solution I can think of would be to completely remove/decommission the SEA VOR.




Synopsis: A TRACON Controller reported an aircraft departing an airport deviated from their SID and into confliction with an air carrier on final approach to an adjacent airport. The reporter stated pilot deviations on this particular SID are a recurring issue.