Date: 201511
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: Small Transport
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Taxi
ATC / advisory: Ground ZZZ
Reporter organization: Government
Reporter function: Ground
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Confusion; Situational Awareness; Communication Breakdown
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway; Ground Incursion Runway
Detector: Person Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; General Flight Cancelled / Delayed
Contributing factors: Airport; Environment - Non Weather Related; Human Factors; Procedure
Primary problem: Human Factors

Narrative: I was working ground control. Aircraft X called for taxi instructions. He initially said he was ready to taxi. He was saying this at the same time that TRACON was speaking to me through my headset so that the aircraft's request to taxi was said through the loud speaker. When he said FBO I mistook it for FBO Y on the field. There was a [same model aircraft] sitting at the FBO Y ramp and aircraft X almost always parks at the FBO Y so on top of the transmission being confusing with two people talking to me at once; there was also an expectation bias on my part. I then instructed aircraft X to taxi to Runway 23 and to cross the approach end of Runway 11; which would be the correct route from the FBO Y. The pilot read back my instructions verbatim; however; he proceeded to immediately cross Runway 5 after Local Control had just cleared someone for takeoff on Runway 23. At the same moment FBO Z called to advise the aircraft that a door had been left open which then immediately drew our attention to the aircraft's position. I told him to exit the runway; make a 180 degree turn and hold short of Runway 5. The aircraft cleared for takeoff had yet to position himself on the active runway.Be extremely cautious of expectation bias. In this instance I suspect that it affected the pilot as well as myself. He is used to a certain taxi route; so he may have been acting on autopilot with the instructions. Always ensure you know and visually observe an aircraft before issuing instructions as both controllers and pilots make mistakes. Also try not to do too many things at once. Instead of trying to coordinate and issue taxi instructions at the same time; I should have attended to one or the other in proper sequence. Nothing is gained by getting task saturated just to attempt to get two; non time critical things done at once.




Synopsis: Controller misunderstood a pilot's position on the airport and issued taxi instructions from a different point on the airport than the aircraft was actually at. The pilot did not question the instructions; which led the pilot to cross an intersecting runway that another aircraft was cleared for takeoff on. The Ground Controller received a call from ground personnel that the aircraft had an open door. This keyed the controller to observe that the aircraft was in a different position than he thought. The controller told the aircraft to exit the runway prior to the takeoff aircraft positioning on the runway.