Date: 201506
Local time of day: 0601-1200
Location: SEA.Airport, WA
Flight conditions: Mixed
Weather elements / visibility: 10
Light: Daylight
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B SEA
ATC / advisory: TRACON S46
Aircraft component: Flap/Slat Indication
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Fatigue; Situational Awareness
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew Executed Go Around / Missed Approach; Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft; Human Factors
Primary problem: Human Factors

Narrative: During approach to land from ILS to 16L; I/we were too slow to recognize the flaps were not extending. It wasn't until we read the Before Landing Checklist with aircraft slowing towards approach speed that I saw the flaps were at zero even though 30 was selected.This was my first flight following two weeks of vacation and first day with new checklists and QRH. I didn't sleep well the night before and therefore was a little tired for the first leg.  As a result of all these factors; I felt my scan and SA were a little off.  Not monitoring the flap indicator as flaps were selected and being slow to put all the pieces together unfortunately showed my habit patterns and scan were not caught up with my normal flow performance.As soon as we noticed the malfunction; we executed a go-around from above 1000' to work the issue.  I don't believe the airspeed got below 150-145 KIAS before executing the go-around. While certainly manageable; using the new QRH for the first time took a little extra time to make sure I was in the right checklist and properly following the new page formats.Just before noticing the zero flaps I saw the slow speed indicator flashing on the MCP panel and was wondering why; about the same time the FO (PF) was thinking it was taking longer than normal for the aircraft to slow.  Had we voiced these concerns to each other; we may have caught the malfunction sooner.


Second narrative: I have flown with the Captain before and I enjoyed working with him and we got along well. I elected to fly the first leg and the flight was uneventful all the way to Seattle. I don't fly [this model] often so I was maintaining a very high level of situational awareness between the FMC and the instruments during the descent and vectors to the approach to the ILS 16 left into Seattle. As we completed the CHINS Arrival into Seattle we were vectored onto a left downwind to 16L. Once on downwind I slowed to 210 knots and I called for flaps one. The Captain set the flap lever to one and normally I would take a look at the flap indicator to make sure they're moving but I was again making sure I kept a high level of situational awareness between the FMC and instrumentation and did not look at the flap indicator. As we turned a left base I called for flaps five and slowed to 170 knots. At approximately three miles from the final approach fix; I called for the landing gear down and flaps 15. The Captain lowered the landing gear and set the flap lever to flaps 15. As I began to slow toward target speed passing through 160 knots I called for flaps 30 and the Before Landing Checklist. The Captain set the flap lever to 30 and began to read the Before Landing Checklist. When the Captain read the flap portion of the Before Landing Checklist; we both looked at the flap indicator and realized it was at zero and at that moment realized we had a flap problem. The Captain immediately called out 'go-around '; to which I immediately began a go-around. As I recall the speed was right around 155-160 when I began the go-around; and we immediately accelerated and climbed to a normal and uneventful go-around. Air Traffic Control leveled us off at 3000' and gave us delaying vectors; and we informed them that we had a flap problem. I (as the Pilot Flying) maintained control of the aircraft and took the radios while the Captain pulled out the QRH and found the appropriate section for the flap failure. Before beginning the alternate flap extension; the Captain wanted to try one more time to put the flaps out normally just to verify that they in fact were still not working. We were flying on an extended downwind at 210 knots and selected the flaps to one; and they extended and indicated normally. We verified on the indicator the flaps for the appropriate position and we also looked out of our windows to verify all the slats visible were down at their correct position and they were. I then slowed to 170 and we selected the flaps to five and they again went to the correct position. We then both agreed that the flaps appeared to be operating normally now and we were vectored on to the ILS to 16 left again and had an uneventful landing with the flaps going to their commanded positions.


Synopsis: B737 flight crew reported flying an approach to the point of Before Landing Checklist before noticing the flaps were not extending as commanded.