B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Distraction; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown; Inflight Event / Encounter Other / Unknown
Flight Crew Became Reoriented
Human Factors; Weather
While switching runways; obtaining new [performance data] we inadvertently took off with flaps set 1 instead of 5. This was my leg to fly. Conditions at the time were light rain; wet runways; gusting and shifting winds. We were also dealing with multiple taxi changes as well as other unusual air traffic control distractions. Events as they unfolded: during taxi to [Runway] 8R we noted that aircraft were being asked to take [Runway] 12. In anticipation of this the Captain had me obtain new [performance data] for a max 26k takeoff for Runway 12. Rain; winds; approaching weather as well as multiple go-arounds on Runway 9 as we were taxing out justified a max 26k takeoff. When the new [performance data] printed I told the Captain we were good for 12 and it was a flaps 5 takeoff. Upon reaching the holding pad for 8R; tower asked us to take Runway 12 and switch to that tower frequency. I switched radios; set up the FMC; reset the MCP and Navigation Display (ND) for Runway 12 takeoff. As the Captain taxied I read and double checked the [performance data] and FMC aloud. At this time we were at the takeoff briefing portion of the mechanical checklist. I picked up the list from this point as were cleared to line up and wait. The Captain asked to verify we were good for 12 and all set. The takeoff acceleration; lift off; and climb out was uneventful. At 1;000 feet I called VNAV cross checked the airspeed just below flaps 1 and called for flaps 1. At this time I heard the Captain exclaim... I double checked the airspeed we were accelerating through flaps 1 so I called flaps up. The rest of the climb out and flight was uneventful. I continued the enroute climb with the auto pilot engaged. The Captain asked if I specifically remembered reselecting flaps 5 for takeoff. I did not remember doing so. I asked why and that's when he told me we had taken off with flaps 1.I am usually very meticulous with my duties especially when it comes to the FMC and configuration. I can only say that the unique combination of weather; ground and radio congestion; as well as unusual operations (multiple aircraft go-arounds and an aircraft instructed to back taxi into position with multiple aircraft waiting in line for example) contributed to the oversite. From now on my personal technique will be to restart the mechanical checklist from the beginning whenever we have new [performance data] or a runway change from what was anticipated when we completed the before taxi check list.
FO flying. Planned Runway 8R; dry Runway; 22K. Right aft fuel boost pump MEL'd with amber light in field of view. Weather moving in as we taxied out. Planes assigned [Runway] 12. Obtained wet [performance data] for Runway 8R and 12 at 26K. Initial flap setting was for 8R at flaps 1. Discussed Runway 12 and [performance data] calling for flaps 5. Subsequent discussions and events involved traffic sequencing; changing taxiways; multiple GAs for south runways; shifting winds; unusual taxi instructions from tower to other planes. Approaching hold short for 8R; switched to 12. FO and I talked about new runway; flaps setting; climb out; MCP; engine out and weather. Elected 26k max power. Asked FO to redo the takeoff checklist. FO acknowledged redoing checklist. Assigned to line up and wait 12. Taking the Runway confirmed that we were legal for 12 and ready to go. The mechanical checklist was completed. Crossed checked power settings; FMC and MCP. Takeoff roll and climb out was normal. No performance issues noted. Once airborne; FO called for VNAV and Flaps 1. I started to move the flaps and without hesitation noted flaps at 1. Returned handle to flaps 1 detent and cross checked PFD for plane performance. Well above V2+15 and approaching flap 1 retraction speed.First time as a pilot that I have taken off with an incorrect flap setting. Factors contributing to this event include but not limited to weather events; ATC communications; and runway change. The bottom line is that I failed to scan and catch the flap handle in the wrong setting. I will have to reconcile this fact on all subsequent takeoffs. How to avoid this event? Clear and deliberate communications. When I asked the FO to 'redo the checklist' I should've said 'Open and redo the entire checklist.' The mechanical checklist would've started from the top and the 'Flaps' challenge and response would've caught the incorrect flap position. The 'Flaps' on the mechanical checklist was previously acknowledged for 8R and not 12.
B737 flight crew reports departing with the flaps set to 1 while a setting of 5 was required after a runway change.