B737-800 first officer reported executing a go-around after receiving a GPWS warning triggered by an...

Narrative:

A go-around was performed due to final landing flaps not being selected below 500 feet. ATIS was reporting 3200 overcast with a few clouds at 300 feet and a temp/dew point of 2/2. We discussed the possibility of the 300 foot clouds being an issue and briefed the ILS and set minimums. We were on approach to 16R behind a heavy 787. We heard the controller give 2 separate speed restrictions to the 787 crew which they incorrectly read back; causing us to question what speed they were flying. We were assigned 170 knots to finka after intercepting the localizer. We slowed; but were subsequently told to slow to 160 knots to finka. We extended the gear and flaps 15. We were descending on the glideslope on autopilot and when we got to finka; we encountered a significant wake turbulence event that caused the aircraft to roll left 20 degrees and caused us to go left of the localizer by close to one dot. We were guarding the controls; but the autopilot stayed connected and corrected back to course. We were noticing the swirling wake of the 787 in the clouds. We continued the ILS and broke out at 300 feet. Just after that we encountered more wake turbulence from the preceding 787; then got a GPWS warning because we were still at flaps 15 and 160 knots. I executed a go-around and we were vectored around the radar pattern for an uneventful landing. We were distracted by multiple things including weather being significantly below what ATIS reported; and finally; the wake turbulence we encountered at finka causing us to worry about aircraft control at that moment instead of configuring to final flap setting. After finka we were concerned with both wake turbulence and the low weather and we neglected to remember to configure our flaps to the final setting and run the before landing checklist.

Original NASA ASRS Text

Title: B737-800 First Officer reported executing a go-around after receiving a GPWS warning triggered by an improper flap setting. Reporter cited distraction following a wake turbulence encounter in trail of a B787.

Narrative: A go-around was performed due to final landing flaps not being selected below 500 feet. ATIS was reporting 3200 overcast with a few clouds at 300 feet and a temp/dew point of 2/2. We discussed the possibility of the 300 foot clouds being an issue and briefed the ILS and set minimums. We were on approach to 16R behind a heavy 787. We heard the controller give 2 separate speed restrictions to the 787 crew which they incorrectly read back; causing us to question what speed they were flying. We were assigned 170 knots to FINKA after intercepting the localizer. We slowed; but were subsequently told to slow to 160 knots to FINKA. We extended the gear and flaps 15. We were descending on the glideslope on autopilot and when we got to FINKA; we encountered a significant wake turbulence event that caused the aircraft to roll left 20 degrees and caused us to go left of the localizer by close to one dot. We were guarding the controls; but the autopilot stayed connected and corrected back to course. We were noticing the swirling wake of the 787 in the clouds. We continued the ILS and broke out at 300 feet. Just after that we encountered more wake turbulence from the preceding 787; then got a GPWS warning because we were still at flaps 15 and 160 knots. I executed a go-around and we were vectored around the radar pattern for an uneventful landing. We were distracted by multiple things including weather being significantly below what ATIS reported; and finally; the wake turbulence we encountered at FINKA causing us to worry about aircraft control at that moment instead of configuring to final flap setting. After FINKA we were concerned with both wake turbulence and the low weather and we neglected to remember to configure our flaps to the final setting and run the before landing checklist.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1412801
Time
Date	201612
Local Time Of Day	0601-1200
Place
Locale Reference	SEA.Airport
State Reference	WA
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	B787 Dreamliner Undifferentiated or Other Model
Operating Under FAR Part	Part 129
Flight Phase	Landing
Flight Plan	IFR
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Inflight Event / Encounter Unstabilized Approach Inflight Event / Encounter Wake Vortex Encounter Inflight Event / Encounter Weather / Turbulence

B737-800 first officer reported executing a go-around after receiving a GPWS warning triggered by an improper flap setting. Reporter cited distraction following a wake turbulence encounter in trail of a B787.