Widebody Transport
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Flight Crew Executed Go Around / Missed Approach
Human Factors
During ILS Approach SEA Runway 16L; I was distracted by above glide slope turn onto the ILS and traffic separation issue which resulted in an unstable approach to a go-around.Above glide slope turn onto the ILS caused early extension of the landing gear which interrupted the normal flow of the before landing checklist. The marginal VFR conditions complicated concerns about sufficient landing separation creating an additional distraction. TCAS indicated 2.5 miles separation from the aircraft in front of us; so I asked Tower for our interval. They responded; our separation was an aircraft 2 miles in front and 2 miles behind us. While sorting out the traffic separation issue; we inadvertently did not select flaps 35 (final landing configuration). Below 500 ft; we got an EGPWS aural call out; too low flaps. We executed an immediate go-around. The cause was human error; we were both distracted by the traffic issue and request to maintain 170 kts to the FAF.[Recommend a] more conservative profile from ATC; better communication (Tower referred to separation from an aircraft ahead of us going to the parallel runway 16R; causing confusion that was a major distraction); and improved checklist discipline (early gear extension disrupted Before Landing Checklist). We made the correct decision to go-around.
Air carrier Captain reported a go-around at SEA attributed to an above glide slope turn onto the ILS and an improper flap configuration on final.