Date: 201507
Local time of day: 0001-0600
Location: SEA.Airport, WA
Aircraft: B737-900
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground SEA
Second aircraft: Dash 8 Series Undifferentiated or Other Model
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: Pilot Flying; First Officer
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Critical
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Took Evasive Action; Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: While taxiing to Runway 34R in Seattle we came very close to being taxied into by a Dash 8. We were just past intersection N on Taxiway B when I saw the [other] aircraft start to taxi toward us from Taxiway W. We didn't hear the Ground Controller give instructions for the [other] aircraft to follow us or for us to follow them to the runway. My FO was going through his briefing as he was to be the pilot flying; while I [was] following along while taxiing. I happen to catch the Dash out of the corner of my eye to our left. They were moving from their position on Taxiway W and I figured they were just getting moving in order to slip in behind us on Taxiway B and would follow us. Then I realized they were not aware of us as they were moving toward us now at rapid closure at an angle that I figured if I were to stop; they would have hit us. It was happening so fast at this point I didn't have a chance to say anything to [the other aircraft] or Seattle Ground Control. All I could think of was to get into a position where the [other] crew would see us; which they fortunately did; and stop. As I mentioned; from the angle and speed they were approaching us I figured if I were to stop; they would have hit us as it appeared the FO in the [other] plane was not looking to their right and I'm not sure were the Captain of the [other] plane was looking. The [other] crew mentioned to the Seattle Ground controller that it would have been nice to have been given a 'heads-up' regarding us as it was a very close call.I think if the [other] crew had been looking to see where they were going they would have seen us. If I had not assumed they were going to follow us; I would have stopped and found out for sure before continuing to taxi. I don't want to point fingers; but it seemed apparent the [other] crew was not looking to their right as they approached the active taxiway. I'm not sure if Seattle Ground told them to follow us or what. We don't recall hearing either way.


Second narrative: I looked up and could see a [Dash 8] taxiing out of the ramp; towards us at an angle. He didn't seem to see us; and was getting uncomfortably close. I said something to the effect of 'We better stop!'; but the Captain (who had a better view of the situation from the left seat) decided to continue so as to get into the [other] pilot's field of view. In hindsight; I believe that this was the right course of action. They did finally see us and stopped. Our wingtip must have missed their aircraft by only a few feet.


Synopsis: B737-900 flight crew reported a near-collision with a Dash 8 while taxiing.