Date: 201705
Local time of day: 1801-2400
Location: APC.Airport, CA
Flight conditions: VMC
Weather elements / visibility: 6
Light: Night
Aircraft: Small Aircraft
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Taxi
ATC / advisory: CTAF APC
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Commercial; Flight Crew Multiengine; Flight Crew Instrument
Human factors: Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Ground Excursion Taxiway
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Contributing factors: Aircraft; Airport; Human Factors
Primary problem: Human Factors

Narrative: The incident occurred while taxiing from transient parking to runway 18R for takeoff. I was taxiing from the transient parking on taxiway Foxtrot (F) enroute to taxiway Alpha (A) and thence on to taxiway Kilo (K) and on to runway 18R. The incident occurred at the intersection of Foxtrot and Alpha. Taxiway lighting on the segment on F from transient parking to A was non-existent; and the single landing light on the aircraft (it has two landing lights and one taxi light; one landing and one taxi light were/are inoperative) was misaligned way to the left of the path of travel and not very bright. Without sufficient lighting; I tried following [another aircraft] on taxiway F to taxiway A; had my passenger shine his small flashlight out his window to help with the lighting and I also tried to use the geosynchroning feature of my ForeFlight software on my iPad to follow the short segment on taxiway F. Unfortunately; I ran off the left edge of taxiway F onto the grass area just short of taxiway A. I immediately pulled back on the yoke to offload weight from the nose wheel and applied power to taxi through the grass and onto taxiway A. Making it safely onto taxiway A; I then performed a series of S turns to test the integrity of the nose wheel. I noted no problem with the nose wheel. Further; on takeoff and landing I noted no shimmy; wobble or other problem with the nose wheel. I flew the airplane from APC to ZZZ with no further incident - the plane flew as expected; easily staying in trim both vertically and laterally. I know that I was the Pilot in Command; and it was my responsibility to maneuver safely; but; for what it's worth; I believe that there were several contributing factors to the incident: 1) the lack of adequate lighting at APC for the short segment of taxiway F; and b) the owner of the aircraft I rented has deferred the repair/maintenance of the taxi/landing lighting system of the aircraft for almost one year; and in my opinion as well as that of my passenger and the squawk sheets on the aircraft; the taxi/landing lighting system condition is inadequate; not only was it misaligned (aiming high and far to the left of the center line of travel) but it was not providing normal amounts of light. Neither I nor my passenger; a licensed pilot; could see the taxiway due to the lack of adequate taxiway lighting and aircraft lighting. I would also recommend that Napa County Airport at least add some blue reflectors on stakes for the leg of Taxiway Foxtrot between the ramp and taxiway Alpha; where there is no overhead lighting nor any taxiway lights to mark the corner.




Synopsis: Single piston engin aircraft pilot reported a taxiway excursion due to poor airport lighting as well as inoperative/misaligned aircraft taxi light.