Fatigue; Communication Breakdown; Distraction; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Flight Crew Executed Go Around / Missed Approach; Flight Crew Took Evasive Action
Human Factors; Procedure
Was PF on last leg of four-day.  This final day was flown with different Captain than previous three days.  I had flown with the Captain numerous times before and had an excellent working (personal and coordination) relationship.  The four-day trip was a higher than average duty hour four-day trip with the last two days of the trip requiring early predawn wake ups.  The last day was the longest at near 11-hour duty day.  In addition; after landing on the final leg; I would be immediately non-revving to XXX; to fly a two-day trip starting the next day. The three previous legs were uneventful; with only a slight delay at the beginning of the third leg due to a very minor line Maintenance repair (tightening a screw).  Weather was only a minor factor on only the last leg requiring minor avoidance deviations enroute.  The arrival and approach brief was accomplished in accordance with Company policies and procedures.  A visual approach was briefed for XXL.  Abeam the approach end of XXL; we were cleared the visual to XXL and to maintain visual separation on aircraft ahead of us to XXL and one on XXR.  Configuration went normal through landing gear down and flaps 15. Rolling onto final; PF focused on not overshooting and PF kept lookout for aircraft on [the parallel].  But due to extra tasking; visual lookout and ensuring not to overshoot and cumulative effect of early wake ups and long last day; Crew communication broke down as call for final landing flaps by PF was not clearly stated nor was it verified; as PF got behind. PF got tunnel vision and began focusing on unusual power settings and associated airspeed.  This caused both Pilots to narrow their focus.  Neither called for Landing Checklist.  At 600' AGL the PF felt something was incorrect and started to state going around. At that moment the GPWS call Too Low Flaps occurred.  PF stated going around and a missed approach was executed followed by a normal visual approach and landing. Ensure don't get complacent following Company prescribed policy and procedures.  Also communicate to Crew Member to keep a keen watch if you have done consecutive early wake ups which may catch up with you especially on last long day of a four-day trip; i.e.; providing them a verbal mental picture of how you're doing!
Landing configuration error resulting in a subsequent go-around. All it took was 10 seconds to ruin a perfectly executed flying day. I believe that fatigue and complacency on my part was a major contributor. This was a very early and long duty day. We had a predawn report at the gate resulting in an even earlier lobby time. In my case; a wakeup two hours before show time. I have been flying PMs the last two months so my body clock was most likely affected. I was flying with one of our best Pilots with exceptional flying talent and skills. We were very familiar and comfortable flying with each other as we have flown together in the past. This was the last of four long flights which blocked 7+12 for the day. Our last leg was from XXX to our domicile with a southern route diversion for weather avoidance. We just finished flying an exceptionally long and circuitous vectors the long way around the south of the the Airspace Airport complex while on the Arrival to XXL. We were both were very familiar with the VFR pattern and procedures. Approach turned us on a very tight base before clearing us for a visual. My First Officer was flying and already called for flaps 5 early on downwind. When we were cleared for the visual; my First Officer called for gear down; flaps 15 as he made the turn to [final]. I was a little preoccupied with the tight turn and sensed we were a little tight and somewhat low. I could also hear that my First Officer was adding power which sounded a little higher than normal. As we rolled out at 500 feet; I made my 500 foot call and I always verify as a technique; 5 green; cleared to land. At that point; almost simultaneously; we both realized that we had not configured the aircraft with flaps 30 and executed a go-around as the GPWS sounded 'Too Low Flaps.' The First Officer executed a flawless go-around and subsequent VFR pattern and landing.It was a very embarrassing and eye-opening experience for both of us! I really do not know how we missed putting the flaps to 30 nor how we missed performing the Before Landing Checklist. I believe a combination of the long duty day; a tight turn to final; target fixation; overconfidence with each other; and even the possibility of the lack of the hot mic function on our older model may have all contributed to our mistake. Thankfully we caught it in time and executed a proper go-around!What I need to do to prevent this from happening again is to go back to the basics; stay vigilant for the entire flight sequence; and try to not become overly comfortable or complacent. I also need to ensure that I force myself to sleep earlier on AM flights. I guess I should try reading the FOM in be - that should do the trick! Also recommend installing a hot mic function on the second generation B737s. We did not have a hot mic; which may have been a contributing factor. I may have missed the flaps 30 call and the Landing Checklist call. In any case; I should not have been distracted and ensured the completion of these two critical actions at the proper time.
A fatigued B737 crew failed to recognize landing flaps were not set at 600 feet AGL. Consequently; the EGPWS TOO LOW FLAPS alerted so the First Officer executed a go-around; configured correctly; and returned for uneventful landing.