Date: 201906
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Situational Awareness; Training / Qualification
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: I've had limited recency flying - 3 legs in the last month; and not much more the month before. That also translates to a small number of legs since the change of checklists; and I don't have a bunch of time in the seat or in the 737 yet; so my habit patterns aren't as well established as I would want - one of the reasons I'm flying a line this month rather than sitting reserve as I have been. Upon pushback today; FO (First Officer) started engine number 2 normally. As the engine was stabilizing at idle; the crew chief came on interphone to ask me to set brakes; and I missed putting the number 2 generator on line. Then when #1 was stabilizing; the flight attendants called with a question and I got distracted from putting generator #1 on line. I checked the rudder as part of the flight controls; called for flaps; and felt I had forgotten something. I glanced at the before taxi checklist and missed the generator step (the APU step's been removed). We taxied out; but didn't have a closeout; so I had the FO tell tower. As I started the turn; ops called to tell us the closeout was coming; and the FO responded. I took radio 1 and told tower we had numbers. There was only 1 aircraft ahead of us; but I taxied slow enough so that the FO could comfortably run through the checklist. When he called 'generators;' I did what I usually do; moved my head a little to the right to try to see if either of the blue gen-off lights were illuminated. It was a bright day; and the lights on this aircraft may be lighter than typical. I didn't see lights; so I responded; 'On.' Upon later inspection; it was clear that these lights were difficult to see unless you moved your head closely in-line with them. The FO couldn't make out the lights; even by moving his head substantially.So we took off with the aircraft on APU generator. Around 15;000 ft; the #1 FA called to tell us he had no galley power. We told him to check breakers; we did the same; and the FO and I looked over the overhead panel and saw nothing wrong. We checked the QRH but found no procedure. I decided to cycle through all of the electrical volt/freq etc. to see if anything appeared wrong. When I got to the APU; I saw that the APU generator was putting out voltage. I looked over and saw that the switch was on; so I turned it off. There went our AC busses. At that point; I realized exactly what I had done. I went to put a generator on line; but that don't work without AC power. I punched off the autopilot horn; and thought for a few seconds. Then I realized why the generators wouldn't come on line; so I put the APU switch back on (it hadn't rolled back yet) and then I restore APU power. Then I was able to put both generators on line.I turned the autopilot back on. Then I checked for instrument flags; FMS load; IRS (Inertial Reference System) status; and we both looked over the cockpit and noted no discrepancies. The aircraft was off AC power for about 5-10 seconds. I called the #1 FA to see if the galleys were working. They were; and the #1 didn't note anything about losing AC power; so I didn't bother with a PA. Nothing was wrong with the aircraft; so I didn't write anything up in the book. I did consider writing up the gen-off lights as being dim; but I couldn't remember if these were worse than typical.The FO and I discussed if there were any other considerations; and there were none. I looked up in the [company SOPs] regarding when to file a [report] and decided that this situation met the criteria; so I told the FO that I would file a [report] and explained to him why he should as well.I think this is one of those events where a lot of elements conspired against us. Distractions; checklist changes; my lack of recency; inexperience; poor human factors for those gen-off lights being so dim (other cockpit lights were bright; so we were fairly sure the lights were not set to dim); and checklist discipline all played a roll.As mentioned above; a lot of things workedagainst us; any of which; if they had not happened; would have likely had us catch the switch configuration error on the ground. Personally; I plan to stay more current; and I have already adjusted my schedule as such. It would be nice if those gen-off lights had brighter bulbs; but I doubt that will happen. I think the before taxi checklist should absolutely restore the APU step. If the FO had asked me if I wanted the APU on; the problem would not have occurred. This checklist change would be an easy fix. In our case; we didn't face a dangerous scenario. Put the jet in the weather though; with a fatigued inexperienced crew; and maybe some other distractions or aircraft malfunction; and I could see things snowballing.




Synopsis: B737-800 Captain reported taking off with the engine generators off-line; citing checklist changes and dim 'Generator Off' lights as contributing.