Date: 201401
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: Turbulence
Aircraft: A300
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Initial Approach
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Flap Control (Trailing & Leading Edge)
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Human-Machine Interface; Fatigue; Distraction; Situational Awareness
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Unstabilized Approach
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Executed Go Around / Missed Approach; Flight Crew Overcame Equipment Problem
Contributing factors: Human Factors; Company Policy; MEL; Aircraft
Primary problem: Human Factors

Narrative: [This was my] second consecutive AM 'out and back' assignment off reserve. The first was delayed approximately 1+15. This trip; my second; [was flown in an aircraft with] the autothrottles MEL'd inoperative. During descent and visual approach to Runway XXL we encountered continuous distractions on the radios due to MULTIPLE similar sounding call signs. One was the exact same digits as ours; two of which were just transposed; plus several others ending in the same number as ours.During the final approach segment of our visual to the runway I let my pilot not flying duties focus to too great an extent on the [pilot flying's] airspeed control which was complicated by the manual throttles and a wind shift. As a result I did not properly back him up and let us descend to the point we received a GPWS 'Too Low Flaps' warning; at which point I called for a go-around. We executed it in accordance with ATC instructions; then re-entered the pattern for a second visual approach to an uneventful landing.My fatigue level had ramped up quite quickly during our 'return' flight. I drank a cup of coffee; but it didn't help enough. I got target fixated on the airspeed and manual throttle control after being distracted by the continuous similar callsigns on frequency.[We need to make] a conscious attempt to change the way the company assigns call signs. A change that focuses on dissimilar phonetics rather ground personnel recognition convenience. Try to use the best aircraft available for these AM 'out and back' assignments. Even though we are returning in the day; which might seem easier; it most definitely isn't. The increased ATC traffic and increased work load associated with MEL's and focusing on so many similar sounding call signs; combined with the additional fatigue that hits once the sun comes up really got me to me today.


Second narrative: When cleared onto final; we noticed winds of 330/50 at 3;000 FT MSL. The winds shifted significantly during the approach until they reached 250/14G20 on the ground. With the autothrottles inoperative; I was working hard to keep the airspeed in a safe regime while configuring the aircraft. Unfortunately; my focus on airspeed control combined with my fatigue lead me to not call for the final flap/slat setting of 30/40. Fatigue from an early morning out and back combined with coming off afternoon flying previously was more significant than I thought it would be.


Synopsis: Fatigue; MEL'd autothrottles and communications problems due to similar call signs contributed to the failure of an A300-600 flight crew to select landing flaps prior to receipt of an EGPWS configuration warning. The flight crew initiated a go-around and flew a second approach uneventfully.