Date: 201708
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Tower ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Distraction
Second reporter function: Captain; Pilot Not Flying
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft Other Automation
When detected: Pre-flight
Contributing factors: Procedure; Human Factors
Primary problem: Human Factors

Narrative: During my Before Taxi Flow the captain was tapping the generator switches as I was preparing to say standby flaps; I thought I had missed something and queried the Captain about it and never got back to the end of the flow. I had a previous Captain who would tap switches lights etc. if I had forgotten something; which is why I thought I had forgotten or missed something. In addition; the Captain had switched the FMCS around from where I had set them; his on the Takeoff page and mine on the LEGS page. These minor distractions led to us missing the flaps. As we taxied; I thought I had missed something; and around the time I assessed everything the Captain did his throttle burst and it was evident what had been forgotten. We stopped the aircraft; set the flaps; reran the Before Taxi and Departure Plan Checklist for good measure; and departed without incident.I think that modifying the Before Taxi procedure and or First Officer (FO) Flow would greatly mitigate no flap taxi out events. When the Captain announces that the Ground Crew is clear he or she should say flaps 1; Before Taxi Checklist; the FO could the set the flaps as the first action on the flow then continue the rest of the flow and then read the checklist. This; I believe would greatly reduce the number of no flap taxi out events and also save time as the flaps would be moving into position while accomplishing the other items on the flow. I have flown professionally for 20 years and never once taxied without flaps until here at Company. There are too many possible distraction points that could happen during that flow especially with the flaps call at the end. Consider moving either the Standing by flaps call to the beginning of the flow; or just removing it and having the Captain call out the desired flap setting from the CDU after the Ground Crew is clear then completing the Before Taxi Flow.


Second narrative: As a Crew; we were getting used to the new Pilot Weather Briefing takeoff procedures. As the Before Taxi Checklist was being run; I (as the Captain) would tap the checklist item i.e. FO 'electrical': Captain tapping generators 'generators on'. FO 'probe heat': Captain tapping probe heat switches 'probe heat on'...and so on. A few times; I tapped the checklist item prior to the FO reading it and believe this inadvertently led the First Officer to think he missed an item on the previous checklist. I believe this because he queried me about it after 'anti-ice' on the checklist at which time I explained what I was doing; and that it had nothing to do with him missing any related items. I believe that this slight interruption (or distraction) caused us to miss verifying the flaps were set to 1 and we taxied out to the runway with the flaps in the up position.We noticed the error on the throttle burst as we got the takeoff configuration warning horn; noticed the flaps weren't set; stopped the aircraft; set the parking brake; and reran the entire Before Taxi Checklist. After the error was corrected; we continued operations normally.


Synopsis: The flight crew of a Boeing 737 reported that they created a disruption in the checklist because of different styles of verification for each item.