Date: 202112
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Airspace: Class B ZZZ
ATC / advisory: Ground ZZZ
Second aircraft: Commercial Fixed Wing
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Confusion; Other / Unknown; Situational Awareness; Time Pressure; Communication Breakdown
Second reporter function: Pilot Flying; Captain
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Took Evasive Action
Contributing factors: Procedure; Human Factors; Environment - Non Weather Related
Primary problem: Ambiguous

Narrative: After landing on Runway XXL at ZZZ; Tower requested that we expedite exiting the runway to enable them to launch a departure.  This was after they were unable to launch this same aircraft ahead of our landing.  We complied with the request and the Captain reduced braking and then we exited at the high speed taxiway.  During the approach and landing we watched and followed the preceding aircraft; Air Carrier Y who had exited at the same taxiway. As we exited the runway intending to follow. Air Carrier Y; the Captain abruptly braked after seeing Air Carrier Z on the inner taxiway converging with our taxi path! Air Carrier Z was taxing southbound on B and moving to follow the Air Carrier Y. I had transitioned to 'heads down' to change to ground frequency and complete after landing flows.  I was startled by the abrupt braking but much more so by seeing an aircraft in our pathway.  It was just after sunset/dark and the Air Carrier Z was not well lit at the aspect angle between our aircraft.  We were not yet on ground frequency and do not know how or where Air Carrier Z was cleared to taxi; nor why they were not directed to taxi on Charlie; the inner parallel that would have prevented the near collision that we were able to avoid.


Second narrative: Just prior to our scheduled departure time; ATC issued us an extensive reroute.  We were certain we had sufficient fuel but conferred with Dispatch to be sure.Then for added confusion; we taxied to Runway XXR for takeoff; a runway I had never seen used for takeoff before.Once airborne; Center queried our strange routing for a flight.  We relayed our understanding; ATC saturation in the state of Florida in general; and possibly ZZZ specifically. The sun began to set as we began our descent; this too became a factor. Runway XYL in ZZZ has no ILS procedure available.  An RNAV (GPS)-XY; was programmed into our FMC as a backup to an expected visual approach. The approach and landing were both uneventful.  The briefed exit/taxi plan was to utilize the high-speed exit 1-A and continue on taxiway 1-A to the gate; airside-X; gate YZ...(to use standard taxi procedures of exit on 1-A; taxi south on taxiway 1; then left on taxiway 2 to 2-A; to enter ramp is difficult due to the radius/turn required to align to that gate from the south...from the west is essentially straight in.)Late in our rollout (midfield or so); ATC asked us to expedite to 1-A  for takeoff traffic; we complied. As we exited the runway; darkness had not set in; I saw our 'interval' (Air Carrier Y); moving slowly southbound on taxiway 1.  I was momentarily distracted by the abnormal taxi speed when I looked straight ahead and saw Air Carrier Z dangerously close in front of us; on our taxiway. In that moment; I thought that Air Carrier Y had stopped for Air Carrier Z and had just restarted their taxi; that Air Carrier Z had turned left onto taxiway 2 from 1-A  (taxied west on 1-A  and turned south onto B).  That either Air Carrier Z had missed taxiway C or was supposed to be closer to Air Carrier Y to avoid a conflict for our clearing of the runway. We stopped abruptly and saw the right wingtip of Air Carrier Z disappear below the nose of our airplane. How did this situation occur?  Unknown!  Not being on ground frequency until we cleared the runway we had no idea of the sequence of events (was someone given questionable instructions from tower or was an error made overshooting the directed taxiway).  I simply do not know.  The ground controller seemed fully unfazed/nonplussed by the near ground collision of two aircraft on his watch. I do know we came very close to colliding with that Air Carrier Z with the nose of our aircraft and who knows what the ramifications of a high speed aircraft plowing into the middle of another might have been. Should I have ignored ATC's request to hustle down to 1-A  and clear?  Maybe...  Should I have expected another airplane to be exactly in the wrong place at the wrong moment?  Possibly...In daylight; I would've seen Air Carrier Z.  Unfortunately; it was dark.  But not all the way dark; where Air Carrier Z's position/strobe lights would have been more visible.  It was dark enough to cast shadows of dark gray; not yet black. Bottom line; we were able to get stopped.  Air Carrier Z's wingtip did not hit us and no one got hurt...this time.  I hate needing to rely on luck!


Synopsis: Air carrier flight crew reported a critical ground conflict after landing and during their runway exit on a high speed taxiway. The pilots stated an abrupt stop was required to avoid a collision. The crew reported there was no instruction or comment from the ATC ground controller.