Date: 201603
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: B787-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Training / Qualification
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Detector: Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: I'm on 787 OE; FO. I served as PM for the [international] flight. I'm coming off a 3-year leave of absence; and in addition to learning a new airplane; international operations; and philosophies; I've had a lot of catching up to do. I can now also allow as how simply a mental return to aviation basics could be added to my to-do list.Conditions were light snow and gusty winds; and [the] Captain did a great job of briefing possible approach scenarios and contingencies. We ended up flying an ILS during which we ended up going VMC shortly past the OM and well before reaching 1000 feet. Originally we briefed for F30; and I was running the checklist and handling the radios; which at this stage in my coming back to work may have been more demanding than I realized; even though we had the FB and FC present on the fight deck to help. And I may have missed [the] Captain's decision to change from an F30 landing to F25 due to earlier-than-usual task saturation.I had the ECL open to 'before landing'; and when we ended up with F25 at about 1000 feet; I looked down and saw the 'flaps' item was still open. Then [the] Captain called for REF+10; and I didn't have a basis for which to set the speed. F30 REF was still programmed in the box. So rather than leave the airplane configured as is; I reached down and selected F30; which created an unstable condition. [The] Captain noted as such; and asked everyone whether we were comfortable with landing out of this condition since it was VMC. Everyone agreed. And we landed without incident.I've mentioned a mental return-to-basics; and that would include not changing the configuration below 1000 feet. I could also have simply overridden the ECL item; and that would've taken care of it; or I could've simply asked [the] Captain what I should do. I remember feeling a modicum of uncertainty when I realized the checklist was technically not complete. Unfamiliarity with the airplane was a causal factor in part. Amazing airplane; fantastic opportunity to come back and resume my career after this long an absence; and the highest-quality training department I've ever seen. [The] Captain is simply the most competent; most intuitive; most effective OE Captain I could ever hope for. I hate to have disappointed him. But I believe his decision to land was still the correct decision to make and did not create any additional safety hazard. A Go Around would have been the less safe decision to make in my estimation.




Synopsis: B787 First Officer reported confusion on short final regarding final flaps setting; related in part to human factors after a long absence from work.