Date: 201907
Local time of day: 0601-1200
Location: JAC.Airport, WY
Weather elements / visibility: Rain; 8
Aircraft: Small Transport; Low Wing; 2 Turboprop Eng
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Airspace: Class D JAC
ATC / advisory: Ground JAC
Reporter organization: Corporate
Reporter function: Captain; Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Confusion
Anomaly: Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Detector: Person Flight Crew
When detected: Taxi
Contributing factors: Airport; Weather
Primary problem: Airport

Narrative: Conducted checklist and taxi to runway. Cleared to taxi to Runway 1. Proceeded from ramp on Taxiway D Southbound on Taxiway A and utilized the southernmost lead in taxiway line; which would give me little longer runway. Approaching runway; heavy rainwater runoff was obscuring runway hold short line; looked to the side for runway signage to verify position of runway hold short line. Immediately advised tower that we our nose had crossed line and tower advised 'Hold Position.' Held position; traffic was not a conflict. After contacting Tower; noticed that the runway hold short marking were in an area where water would naturally run; lowest point of the taxiway. This made the hold short markings hard to see when approaching from the Taxiway A and runway hold short is unusually close to the taxiway in the turn. Secondly; the taxiway lead in line is at an angle to the runway hold short and line. Furthermore; and predominant issue; there was also a second band of water approximately 30 feet of my position forming an illusion of line which I had perceived as location runway hold short line; which I mistook for hold short markings. What with the rain; lower light due to cloud cover; surface water pooling on hold short lines. I had made the error of crossing hold short line. Once over the line; the water front seat passenger (also a pilot) took picture of the water runoff and pooling; making it obvious that the water was obscuring the markings. He also verified that the markings were hard to distinguish. I have used this airport multiple times and aware of proximity of runway. I am not a stranger to this airport; but don't believe I had ever been in a position to make this error with the environmental conditions at play. Close proximity of Taxiway A; with little lower light; water covering hold short markings contributed to this matter. I feel I should contact someone with regard to water drainage in this area. If the hold short markings were three feet forward or aft of present position they would not have been as hard to see. If I had used first taxi lead in markings angle to runway less of a curve and more of a camber to taxiway and better drainage. I am aware runway incursion is a major issue. I have cautioned another pilot at this very same airport of close proximity of runway marking to taxiway and interjected with over-riding on braking. In future would not turn and remain south facing position; so as not to encroach runway; until cleared for take-off. Personally; the hold short at this airport appears unusually distant from runway centerline; not what one would expect or anticipate; but a line is a line.




Synopsis: Small transport pilot reported with low light and rain runoff; taxiway A1 hold short lines are obscured.