B737-700
Air Traffic Control Fully Certified
Communication Breakdown; Situational Awareness
Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert
Human Factors; Procedure
There is limited wing tip clearance because of taxiway convergence at B6 on Taxiway B at PDX. This is an identified hot spot on the movement area. Aircraft are often pushed back from the A gates and partially extend on Taxiway B. ATC uses the intermediate hold line west of B6 to hold aircraft short when one is pushed back from the A gates and wingtip clearance cannot be ensured. Working Ground Control; I taxied a B737 to Runway 28L via B5; B to hold short of B6. The read back was good but the aircraft rolled past the B6 hold line. The aircraft did stop short of the pushed-back aircraft I was protecting. I did a little pilot education on frequency and the pilot stated he did not see/understand that to hold short of B6 meant short of the hold line since it was so far from the actual runway exit B6. So he so rolled past it. This hot spot sees recurring incidents by pilots unfamiliar with this airport. The local pilots are acutely aware of the issue. [I] recommend a verbiage change when instructing aircraft to 'hold short of Bravo Six ' for the wingtip clearance hot spot. 'Hold short of the Bravo Six intermediate hold line' or some such would be a better locally adapted phrase. Recommend the common practice in this country of aircraft switching on their own from Ground Control to Local Control be looked at. In other countries aircraft must receive instructions to leave Ground Control frequency and contact Local Control. In most other communications changes in the NAS you cannot leave the frequency until instructed to do so by ATC; although not between Ground Control and Local Control.
PDX Controller recommended a locally phraseology change when instructing aircraft to 'hold short of Bravo Six;' noting a recent failure of a taxiing aircraft that led to a potential wing tip clearance issue.