B737-900
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 207; Flight Crew Type 905
Human-Machine Interface; Situational Awareness; Workload
Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Executed Go Around / Missed Approach
Human Factors
Night IMC through WX. Dark cockpit; procedures followed. Simply missed flap setting. I erroneously executed Landing Checklist. Instead of Flaps 30; Green Light; Flaps were actually Flaps 25: with a Green Light. Runway was in sight; FO (First Officer) flying; AP; AT off. GPWS call came approaching 500 ft. AGL; TOO LOW; TERRAIN; followed by TOO LOW; FLAPS. I called for and we immediately executed a go-around without incident. Was very busy go-around 1200-1400 ft. ceilings; IMC above airport and busy. Initial altitude 1700 ft. MSL; multiple vectors to downwind and low altitude. Followed vectors around to set up for [another approach]. And just to make sure we had practice; Tower cancelled approach clearance at 1500 ft. AGL due traffic compression. Went around and did it again.
Uneventful flight; excellent crew communication/coordination; checklists completed in timely manner; on approach (gear down; flaps 15); I requested flaps 30 - landing checklist. Captain moved flap handle and used checklist to read landing check list. On short final; 'too low flaps' was heard; Captain acknowledged and stated 'go around'; a go-around was executed; following standard go-around procedures and by all accounts event was a successful go-around and after checklist was completed Captain coordinated another approach to airport; and while on approach; ATC advised us of slower aircraft ahead and assigned speed; we complied and shortly thereafter; ATC apologized and issued 'go around' due to slower traffic ahead. We initiated another go-around and all procedures followed and it was a successful go-around. Once checklists complete; with my knowledge; Captain called and briefly spoke to flight attendants to inform of events.ATC vectored us for approach; and approach was successful. Upon landing; Captain made an appropriate and informative announcement to passengers regarding events. After arrival to gate and passenger deplaned; Captain and I debriefed events.
B737-900 flight crew reported executing a go-around after receiving a GPWS warning 'Too low; flaps' on approach.