Narrative:

During taxi to [runway] 15R I was forced to make a quick stop to avoid hitting a company aircraft coming out of our blind spot from behind and to our left. Ground control had cleared both of us to runway 15R via the same routing and I believe ground forgot about our company aircraft altogether after giving us a number of revisions as to which aircraft we were to follow. Ground requested we follow a company aircraft coming from the backside of the concourse; then to proceed to runway 15R. We allowed company access and then we were amended again and told to follow another company that had just finished deicing in the 15R pad.I began a 'slow roll' (give passengers the idea we were still getting there; <5 knots) taxi to allow company to leave the deice area with plenty of space between us. I cleared to our left and could not see anyone in my field of vision on taxiway P. I initiated the turn onto H; still at a slow roll; and turned back towards the deice area to gauge our distance from the company we were advised to follow and; when turning back to the left; I was startled to see another company moving quickly ahead of us on taxiway P. I applied the brakes firmly and estimate the company's wingtip missed our nose by about 20 ft or so. The flight attendants were up making their announcements; but fortunately; they were not thrown down by my abrupt stop. We remembered this aircraft getting a clearance the long way around to [runway] 15R after we made our stop and believe that ATC simply forgot about him or didn't expect him to be a factor because of the taxi distance he was traveling. My slow taxi may have aggravated ATC's mistake in a couple of ways. First; it led me into a false sense of security. Having cleared to my left already; my blind spot was made even larger by the fact that I wasn't hurrying to occupy the limited space behind that I knew to be clear and my attention was diverted back to the opposite side and the aircraft we were to follow. Additionally; my slow taxi may have led our company aircraft on P to believe that I was yielding to him; when I was in fact still in motion towards P. I also believe the company aircraft on P could have been a bit more proactive in confirming his sequence when ground cleared us to follow an aircraft that was now taking P in front of him.

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Original NASA ASRS Text

Title: B737-300 Captain taxiing to the runway at BWI reported having to make a sudden stop to avoid a collision with another Company aircraft.

Narrative: During taxi to [Runway] 15R I was forced to make a quick stop to avoid hitting a Company aircraft coming out of our blind spot from behind and to our left. Ground Control had cleared both of us to Runway 15R via the same routing and I believe Ground forgot about our Company aircraft altogether after giving us a number of revisions as to which aircraft we were to follow. Ground requested we follow a Company aircraft coming from the backside of the concourse; then to proceed to Runway 15R. We allowed Company access and then we were amended again and told to follow another Company that had just finished deicing in the 15R pad.I began a 'slow roll' (give passengers the idea we were still getting there; <5 knots) taxi to allow Company to leave the deice area with plenty of space between us. I cleared to our left and could not see anyone in my field of vision on Taxiway P. I initiated the turn onto H; still at a slow roll; and turned back towards the deice area to gauge our distance from the Company we were advised to follow and; when turning back to the left; I was startled to see another Company moving quickly ahead of us on Taxiway P. I applied the brakes firmly and estimate the Company's wingtip missed our nose by about 20 FT or so. The Flight Attendants were up making their announcements; but fortunately; they were not thrown down by my abrupt stop. We remembered this aircraft getting a clearance the long way around to [Runway] 15R after we made our stop and believe that ATC simply forgot about him or didn't expect him to be a factor because of the taxi distance he was traveling. My slow taxi may have aggravated ATC's mistake in a couple of ways. First; it led me into a false sense of security. Having cleared to my left already; my blind spot was made even larger by the fact that I wasn't hurrying to occupy the limited space behind that I knew to be clear and my attention was diverted back to the opposite side and the aircraft we were to follow. Additionally; my slow taxi may have led our Company aircraft on P to believe that I was yielding to him; when I was in fact still in motion towards P. I also believe the Company aircraft on P could have been a bit more proactive in confirming his sequence when Ground cleared us to follow an aircraft that was now taking P in front of him.

Data retrieved from NASA's ASRS site as of July 2013 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.