Date: 201701
Local time of day: 1201-1800
Location: STS.Airport, CA
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Taxi
Reporter organization: Personal
Reporter function: Single Pilot; Pilot Flying
Reporter qualification: Flight Crew Private
Human factors: Communication Breakdown; Situational Awareness
Second reporter function: Ground
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway; Ground Incursion Runway
Detector: Person Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: After ATIS check on ramp; contacted ground control for taxi clearance; requesting straight out departure from Runway 14. I received clearance to taxi to 14 via Kilo; Alpha; which I read back. I am not familiar with the airport layout; but my aircraft is equipped with an EFIS including airport layout diagrams; and I monitored my progress during taxi on the moving map display. As I arrived at the run-up area; I noticed signage at taxiway Hotel; showing both Runway 20 and 14. It appeared that to reach Runway 14 would require I enter Runway 20. I thought there was another run up area at the end of 14 ahead; so I continued toward the end of Runway 14. Seeing the hold line and blinking light; but thinking I was cleared to taxi to 14; I hesitated; but then continued through the Runway 20 approach hold zone to the end of 14. When I arrived; Ground Control directed me to hold my position and contact the Tower; which I was about to do. I was subsequently cleared for takeoff with a straight out departure. On climb; I was asked to call ATC once I was back on the ground.My later discussion with STS tower indicated that my taxi clearance was to the 14 run up area; which I misinterpreted as Runway 14. I have no recollection of the run-up area being mentioned in my taxi clearance; but it could be that I simply wasn't listening for this distinction. My unfamiliarity with the airport; despite my sophisticated cockpit display; led me to believe that I was cleared to cross the hold line on my way to Runway 14.


Second narrative: I was training a developmental controller on Ground Control. Developmental issued Aircraft X taxi instructions from the FBO to the Runway 14/20 run-up area via Taxiway A. Aircraft X read back taxi instructions. Aircraft X was observed by Local Control crossing the Runway 20 approach hold area without authorization. No other aircraft were involved. Aircraft X was issued Brasher warning by Local Control.Ground Control scans the taxiways to help prevent unauthorized incursions into the Runway 20 approach hold area; but this one was simply unnoticed by Ground Control. Most local aircraft are familiar with the Runway 14/20 run-up area; but transient aircraft will often attempt to taxi all the way to the approach end of Runway 14 to perform a run-up unless Ground Control intervenes (via Taxiways A1 or A2). When Runways 14 and 20 are in use; Ground Control issues taxi instructions for aircraft requiring a run-up to the Runway 14/20 run-up area via Taxiway A. The run-up area is approximately 1000' from the approach end of Runway 14; many pilots are accustomed to taxiing all the way to the approach end of a runway to perform their run up. Perhaps changing the name of the run up area from 'Runway 14/20 run-up area' to something like 'run-up area Alpha' would indicate to the pilot that they are to taxi to an intermediate area for run-up prior to receiving runway assignment.


Synopsis: General Aviation pilot reported a runway incursion resulted at STS airport due to the lack of familiarity with the airport and a miscommunication with Ground Control.