Q400
Flight Crew Air Transport Pilot (ATP)
Fatigue; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Unstabilized Approach
Flight Crew Executed Go Around / Missed Approach
Company Policy; Human Factors
Performed go around on visual approach.  It was initiated when message was received; 'TOO LOW CONFIG FLAPS'.  Flaps were set in 15 position with EGPWS setting at intended 35; and aircraft descended below 500 feet engaging EGPWS.  Successful and safe missed approach completed and flight landed on subsequent visual landing safely.While currently at flaps setting of 10; Pilot flying called for flaps setting of 35 instead of what we do normally from 15 to 35; so there was an expectation bias of only moving flap lever 1 notch.  Neither pilot double checked the flap indicator after flaps where assumed to be selected to 35 so a huge lapse in attention to detail.It was first day of 2 day trip that started with a XB:10 show; this was 5th leg close to 11th hour of duty.  Captain was originally scheduled for PM reserve this day but was switched day prior to AM reserve starting at XA:30 with the subsequent XB:10 show.  These added to lack of awareness due to crew possibly being tired.
A Q400 Captain reports requesting flaps to 35 from the flaps 10 position during a visual approach. The normal call is flaps 15 from flaps 10 and this is what the First Officer selects. The error is not detected until the EGPWS alerts at 500 feet; 'too low flaps' and a go-around is initiated.