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.

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Original NASA ASRS Text

Title: 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.

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.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.