B767-300 and 300 ER
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 30; Flight Crew Total 20000; Flight Crew Type 6000
Time Pressure; Distraction; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Flight Crew Became Reoriented
Procedure; Human Factors
Preflight and pushback with normal engine start was accomplished with no threat or stress. This was the second flight using [a new performance procedure] for both me and the first officer. Our planned runway was 25R at intersection F. We received a taxi clearance for 25L (Alfa hold short of Foxtrot). I asked for flaps 5 and we start moving. Then LAX ground control told us taxi 25L left; but to have the numbers ready for 25R at Foxtrot intersection. I briefed the takeoff and called for before takeoff checklist. We both pointed to flap indicator and responded 5. First Officer started reconfigure for 25L. He finished reconfiguration when we were holding short of taxiway Foxtrot. We both verified the change in runway by using the QRH procedure for 'takeoff runway or performance procedure change'. We then got clearance to hold short of 25L. 25L was a landing runway and their intention was to have us take off after two landing aircraft. We got clearance to taxi in position and hold with reminder of aircraft on final. When we got the clearance for takeoff I advanced the power levers and pushed N1. Immediately we got the FLAP configure warning. I reached quickly for flap lever to verify it was in its detent. The flap lever was not in the detent and I moved the flap lever to flaps 5 quickly. The configure warning silenced quickly and we proceeded with a normal take off. Before rotation speed I looked at the flap indicator to verify that it was 5 and then executed a normal take off and departure. In hindsight I should have never reached for the flap lever. Instead I should have initiated a rejected take off. When we got a runway change with our taxi clearance I should have asked the ground control if it would be possible to stop on the taxiway and accomplished runway change procedure. The stress factor went from none to very high when we got the runway change and a short taxi with the new performance procedures on a very busy airport. How we both miss-read the flap indicator on the before takeoff checklist I have no idea; maybe we were too occupied in our minds with the new performance procedures.
[Report narrative contained no additional information.]
B767-300 flight crew reported they failed to follow SOP after receiving a takeoff warning horn on initial throttle application. A late runway change and new performance data procedures were cited as contributing factors.