Date: 201306
Local time of day: 0001-0600
Location: SMO.Airport, CA
Flight conditions: VMC
Light: Daylight
Aircraft: Small Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 91
Flight plan: IFR
Mission: Ferry / Re-Positioning
Flight phase: Taxi
ATC / advisory: Ground SMO
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor
Human factors: Situational Awareness; Confusion; Communication Breakdown
Anomaly: Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Detector: Person Air Traffic Control; Person Flight Crew
When detected: Taxi
Result: Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action; Flight Crew Returned To Clearance
Contributing factors: Airport; Chart Or Publication; Environment - Non Weather Related
Primary problem: Ambiguous

Narrative: We departed the [FBO's] ramp at SMO. I was PIC and pilot not flying. The SIC was the pilot flying. During our taxi on the confined [FBO] ramp; we both monitored the taxi situation to ensure clearance from buildings and other aircraft. Once clear of obstacles; I looked down to retrieve paperwork and the taxi checklist. The pilot flying missed the taxiway centerline and continued beyond the designated taxiway. I glanced up and noticed the pilot flying had continued straight ahead past the taxiway centerline and had only just started a left turn to join the taxiway. At this moment; the Tower called and instructed us to continue our left turn and join Taxiway Alpha. We joined the taxiway centerline and continued with a normal departure. The pilot flying stated he was confused by the taxi markings and missed the turn. The taxiway has a standard solid yellow centerline. Double yellow lines form the boundaries of the taxiway. These double lines however are long dashed lines; not solid. These were the markings that the SIC said were confusing. At the intersection of the [FBO] ramp and Taxiway Alpha; I do not believe there are any taxiway direction signs or runway direction signs. Runway entry and/or runway directions signs would be very helpful at this location on the field to assist pilots with situational awareness and help ensure aircraft remain on the designated taxiway. I also do not believe that standard runway hold short lines are used along this section of pavement which serves as both ramp and runway. I believe we taxied outside the designated taxiway; but I do not believe we entered the runway environment without clearance. No aircraft were taking off or landing at the time and no aircraft operations were affected.

Callback: The reporter suggested using similar NON MOVEMENT AREA BOUNDARY markings as BUR does just beyond the outboard side of the taxiway boundary. He suggests pilots would see the solid yellow and dashed yellow painted markings in the tarmac and realize they are approaching a boundary. As conditions exist now he felt that there was a no man's land and the taxiway boundary and centerline were not clearly defining the boundaries.



Synopsis: A flight crew taxied out from the FBO Ramp and missed Taxiway A centerline at SMO; the taxiway signage and markings did not clearly indicate the taxiway boundary.