Narrative:

Instructed by bos tower to 'position and hold on the numbers' runway 4L. Had just begun to move aircraft from a standing start on south taxiway into position when my first officer and I were surprised by a twin aircraft small transport, also taxiing, overtaking us from behind on our right, moving fast. This aircraft apparently had come up behind us on intersecting taxiway east and was transiting across runway 4L on instructions from ground control (my presumption as neither my first officer nor I recall hearing any instructions to other aircraft on tower frequency regarding our runway. Estimate wing tip passed within 3-4 ft of our aircraft. No notification was given to us regarding this other aircraft that had been given instructions to taxi in extremely close proximity to our aircraft. The aircraft was not yielding and in fact seemed to be accelerating, despite the fact that he was the overtaking aircraft. After the conflict occurred it became quite clear why the controller instructed us to 'position and hold on the numbers.' this was to allow room for the other aircraft to cross the runway between our aircraft and the runway threshold. The controller should have told us about the other aircraft.

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Original NASA ASRS Text

Title: FLC OF ACR LTT ACFT WERE ALARMED BY A NEAR TAXI MISS BY AN SMT ACFT.

Narrative: INSTRUCTED BY BOS TWR TO 'POS AND HOLD ON THE NUMBERS' RWY 4L. HAD JUST BEGUN TO MOVE ACFT FROM A STANDING START ON S TAXIWAY INTO POS WHEN MY FO AND I WERE SURPRISED BY A TWIN ACFT SMT, ALSO TAXIING, OVERTAKING US FROM BEHIND ON OUR R, MOVING FAST. THIS ACFT APPARENTLY HAD COME UP BEHIND US ON INTERSECTING TAXIWAY E AND WAS TRANSITING ACROSS RWY 4L ON INSTRUCTIONS FROM GND CTL (MY PRESUMPTION AS NEITHER MY FO NOR I RECALL HEARING ANY INSTRUCTIONS TO OTHER ACFT ON TWR FREQ REGARDING OUR RWY. ESTIMATE WING TIP PASSED WITHIN 3-4 FT OF OUR ACFT. NO NOTIFICATION WAS GIVEN TO US REGARDING THIS OTHER ACFT THAT HAD BEEN GIVEN INSTRUCTIONS TO TAXI IN EXTREMELY CLOSE PROX TO OUR ACFT. THE ACFT WAS NOT YIELDING AND IN FACT SEEMED TO BE ACCELERATING, DESPITE THE FACT THAT HE WAS THE OVERTAKING ACFT. AFTER THE CONFLICT OCCURRED IT BECAME QUITE CLR WHY THE CTLR INSTRUCTED US TO 'POS AND HOLD ON THE NUMBERS.' THIS WAS TO ALLOW ROOM FOR THE OTHER ACFT TO CROSS THE RWY BTWN OUR ACFT AND THE RWY THRESHOLD. THE CTLR SHOULD HAVE TOLD US ABOUT THE OTHER ACFT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.