Narrative:

After receiving our weights and takeoff performance; we were cleared to push for a runway 9 departure. Our performance was for runway 9 with flaps 1. It was entered using the gw (gross weight) from the aircraft performance page. I was instructed to only start the #2 engine and we'd start the #1 as soon as we started rolling so we could get to the runway faster. When ready to taxi; ramp control instructed us to taxi to spot X for 15L. I quarried her since our initial assignment was Y. She changed the taxi instruction to spot za for runway 9 which is a very short taxi. I immediately began the delayed engine start followed by the after delayed checklist. By this time; we were at spot 22 where I switched to metering; followed by the tower frequency. I listened up on the flight attendant intercom to make sure they were ready. The tower cleared us for takeoff. I ran the before takeoff checklist. After lining up with the runway; the captain advised that it was my airplane. I spooled up the engine as per procedures then pressed the toga button and stated set thrust. I removed my hands from the throttle and the ca confirmed the power. At this time my attention is outside the airplane to maintain the centerline. I noticed the ca reach over and moved the flap lever from 1 to 5. I asked why he did that. By the time he responded; we were approaching 100 kts. He pointed to flaps 5 on my takeoff page. At this point; the safest thing to do was fly the airplane. Once airborne; he said that he'd received a new performance uplink and had sent for new numbers while I was starting the #1 engine. I looked down and saw both weight printouts. The first showed flaps 1 and the 2nd showed a higher gw (still less than the aircraft gw) and flaps 5. I estimate we were moving 10-20 kts when the captain moved the flaps from 1 to 5.

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Original NASA ASRS Text

Title: B737 First Officer reports a rushed takeoff caused by a short taxi with a delayed engine start. During the event the Captain had sent for new takeoff data which showed a flap setting change from 1 to 5. As the First Officer begins the takeoff roll; the Captain moves the flap lever from 1 to 5.

Narrative: After receiving our weights and takeoff performance; we were cleared to push for a runway 9 departure. Our performance was for RWY 9 with flaps 1. It was entered using the GW (Gross Weight) from the aircraft performance page. I was instructed to only start the #2 engine and we'd start the #1 as soon as we started rolling so we could get to the runway faster. When ready to taxi; ramp control instructed us to taxi to spot X for 15L. I quarried her since our initial assignment was Y. She changed the taxi instruction to spot ZA for runway 9 which is a very short taxi. I immediately began the delayed engine start followed by the after delayed checklist. By this time; we were at spot 22 where I switched to metering; followed by the tower frequency. I listened up on the FA intercom to make sure they were ready. The tower cleared us for takeoff. I ran the before takeoff checklist. After lining up with the runway; the Captain advised that it was my airplane. I spooled up the engine as per procedures then pressed the TOGA button and stated set thrust. I removed my hands from the throttle and the CA confirmed the power. At this time my attention is outside the airplane to maintain the centerline. I noticed the CA reach over and moved the flap lever from 1 to 5. I asked why he did that. By the time he responded; we were approaching 100 kts. He pointed to flaps 5 on my takeoff page. At this point; the safest thing to do was fly the airplane. Once airborne; he said that he'd received a new performance uplink and had sent for new numbers while I was starting the #1 engine. I looked down and saw both weight printouts. The first showed flaps 1 and the 2nd showed a higher GW (still less than the aircraft GW) and flaps 5. I estimate we were moving 10-20 kts when the Captain moved the flaps from 1 to 5.

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.