A B737 PLT IS CONCERNED THAT MULTIPLE TAXI LANES BETWEEN CONCOURSES B; C AND THE RAMP EDGE ON TXWY B AT SEA ARE INADEQUATELY MARKED AND MAY CONSTITUTE A HAZARD WHEN INBND ACFT ARE INSTRUCTED TO PASS ABEAM ACFT AWAITING DEP ON THE NBOUND RWYS AT TXWY Q.

Narrative

A POTENTIAL GND MISHAP IS VERY REAL AT SEATAC ARPT. WHILE ACFT TAXI FOR TKOF (ESPECIALLY TO THE N RWYS 34L AND 34R/TXWY Q) NUMEROUS PLANES LINE UP. MEANWHILE AS PLANES LAND AND TAXI BACK TO CONCOURSE B; S; OR A GATES; THESE ACFT ARE ROUTINELY ASKED TO TAXI E OF THE PLANES ON TXWY B. THIS IS A VERY TIGHT FIT AND REQUIRES PLTS TO DETERMINE THEIR OWN WINGTIP CLRNC WHICH IS VERY DIFFICULT AND SOMETHING THEY ARE NOT TRAINED FOR. THIS IS THE ONLY ARPT IN THE USA THAT I CAN THINK OF WHERE PLTS ARE REQUIRED TO PROVIDE THEIR OWN WINGTIP CLRNC. IN ADDITION; THERE IS A VEHICLE ROAD NEAR THE CONCOURSES. NUMEROUS LARGE TRUCKS ALSO POSE A GND MISHAP POTENTIAL AS ACFT 'SQUEEZE' BETWEEN ACFT TO THE W AND VEHICLES TO THE E. ON MANY ACFT PLTS CANNOT EVEN SEE THEIR WINGTIP FROM THE COCKPIT. SUGGESTION: PAINT A DOTTED LINE E OF TXWY B WHICH WE CAN TAXI ON AND LIST THE ACFT TYPES WHICH CAN UTILIZE THIS DOTTED LINE AND CAN SAFELY PASS CERTAIN ACFT TYPES ON TXWY B. PUT THIS INFO ON THE 20-9 PAGE SO PLTS KNOW FOR SURE WHICH ACFT THEY CAN SAFELY PASS WHILE KEEPING CLR OF VEHICLE TFC TOO.