Large Transport
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2.5
Communication Breakdown; Confusion; Situational Awareness
Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway; Ground Incursion Taxiway
Air Traffic Control Provided Assistance; Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Flight Crew Became Reoriented
Airport; Environment - Non Weather Related; Human Factors
Aircraft X landed on Runway 27. I issued exiting instructions: 'Aircraft X; turn right on [taxiway] K then turn right on [taxiway] M.' They were read back correctly. I looked away for something else; then looked back and Aircraft X had missed the right turn on M and was continuing straight ahead on K; which then crosses the active departure runway. I was able to stop the aircraft to avoid a runway incursion; but only because I had looked back in that direction in time.I am submitting this to add to the database of potential runway incursions. There is nothing else that can be done. Unfortunately; here at Boston; the airport and runway layout is so complex that it is not conducive to mitigating runway incursions. In every configuration; active runway crossings with a majority of the traffic are necessary and more incursions are avoided only because of the vigilance of the controllers.
An aircraft taxiing to parking missed a turn and was proceeding toward an active runway. ATC noticed the deviation and corrected the pilot. The aircraft had been issued correct instructions and read the instructions back correctly.