Narrative:

On climb out; we received an 'airspeed low' alert twice. Initially; we thought we may have taken off without flaps (1) extended. However; what we deduced was that I (pm) retracted the flaps when the first officer called for 'gear up'. There were several additive conditions that probably contributed to my fault. First was fatigue. This was the first flight of the day with a relatively early start time for a pm trip. The overnight was short. For me; the room temperature was very warm and uncontrollable (central heat) providing for less than optimal sleeping conditions. The prior night was even worse; the crew hotel was host to a very large youth event and the kids were running all over the hotel at all times of the day and night. Second; the radar would not test properly and required us to troubleshoot with maintenance. Third; our departure runway was changed immediately after pushback. Nevertheless; I did not feel rushed; and we completed the information only write up and departure plan review in a timely fashion. The taxi out and takeoff roll were uneventful. I don't remember the first officer calling for gear retraction; I don't remember moving the flap handle either. Up to the point of the 'airspeed low' alert; it was a very quiet; systematic and normal takeoff. With the annunciation of the 'airspeed low' alert; I immediately looked at our airspeed. Initially; I was confused why the low airspeed caution band was 'higher' than what I would have expected; but the speed was as expected for that phase of flight in those conditions; we were accelerating normally; the pitch of the aircraft was normal as expected; and the power was normal and as expected. The alert soon dissipated and we began to analyze what had happened.I realize (with hindsight) that we could have added power since it had been a reduced thrust takeoff. Nevertheless; the first officer (PF) continued to fly the aircraft through the whole incident. We immediately noticed that the flaps were in the up position and initially thought we had taken off without flaps. This led me to question myself; 'how this could have happened'; given all the procedures we would have had to miss. I then noticed that the gear was still down and then reached over to retract the gear. I don't know if I moved the flap handle when the first officer called for gear up. I don't know if the first officer incorrectly called for flaps up and I blindly complied. In either case; I failed to be an effective pm. I would hope that this event has forever elevated my awareness of my duties as a pm; especially during critical phases of flight.

Google
 

Original NASA ASRS Text

Title: After takeoff; B737 crew raised the flaps from flaps 1 to up prior to reaching the minimum cleanup altitude or attaining minimum maneuvering speed for flaps up. Crew received an 'Airspeed Low; Airspeed Low' aural alert and reacted by lowering the nose and quickly gaining sufficient airspeed.

Narrative: On climb out; we received an 'Airspeed Low' alert twice. Initially; we thought we may have taken off without flaps (1) extended. However; what we deduced was that I (PM) retracted the flaps when the FO called for 'Gear Up'. There were several additive conditions that probably contributed to my fault. First was fatigue. This was the first flight of the day with a relatively early start time for a PM trip. The overnight was short. For me; the room temperature was very warm and uncontrollable (central heat) providing for less than optimal sleeping conditions. The prior night was even worse; the crew hotel was host to a very large youth event and the kids were running all over the hotel at all times of the day and night. Second; the radar would not test properly and required us to troubleshoot with Maintenance. Third; our departure runway was changed immediately after pushback. Nevertheless; I did not feel rushed; and we completed the information only write up and departure plan review in a timely fashion. The taxi out and takeoff roll were uneventful. I don't remember the FO calling for gear retraction; I don't remember moving the flap handle either. Up to the point of the 'Airspeed Low' alert; it was a very quiet; systematic and normal takeoff. With the annunciation of the 'Airspeed Low' alert; I immediately looked at our airspeed. Initially; I was confused why the low airspeed caution band was 'higher' than what I would have expected; but the speed was as expected for that phase of flight in those conditions; we were accelerating normally; the pitch of the aircraft was normal as expected; and the power was normal and as expected. The alert soon dissipated and we began to analyze what had happened.I realize (with hindsight) that we could have added power since it had been a reduced thrust takeoff. Nevertheless; the FO (PF) continued to fly the aircraft through the whole incident. We immediately noticed that the flaps were in the up position and initially thought we had taken off without flaps. This led me to question myself; 'how this could have happened'; given all the procedures we would have had to miss. I then noticed that the gear was still down and then reached over to retract the gear. I don't know if I moved the flap handle when the FO called for gear up. I don't know if the FO incorrectly called for flaps up and I blindly complied. In either case; I failed to be an effective PM. I would hope that this event has forever elevated my awareness of my duties as a PM; especially during critical phases of flight.

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.