Date: 201911
Local time of day: 0601-1200
Location: DEN.Airport, CO
Flight conditions: VMC
Light: Night
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Airspace: Class B DEN
ATC / advisory: Tower DEN
Second aircraft: Commercial Fixed Wing
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown; Confusion
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Illness / Injury
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action; General Physical Injury / Incapacitation
Contributing factors: Aircraft; Human Factors; Procedure
Primary problem: Human Factors

Narrative: We were leaving DEN. Ramp cleared us to taxi out on AA to spot 1W (the SW corner of the DEN ramp area) and contact Ground there. As we approached the spot; we called Ground. We were told to 'Give way to Aircraft Y; taxi to Rwy 25 via Golf; and switch tower on 128.75'. I remained holding short of Golf on 1W and gave way to Aircraft Y that turned right from Twy Golf at 1W to go west. My FO (First Officer) and I conferred with the 10-9 and agreed that G was a 60-degree left turn to the south. I turned my taxi light on as Aircraft Y turned away and started easing forward to make the left turn onto Golf. I looked to the right one last time; and was horrified to see [another aircraft] (I believe it was Aircraft Z) darting right to left from behind my FO's shoulder; traveling South on Golf at a speed that I would estimate at 40 to 50 knots. I was just entering Golf and had to slam on my brakes to avoid a collision. No one on my aircraft was thrown to the ground; but the number three flight attendant stated that when she caught herself from falling by grabbing a seat back; she strained her neck. She didn't request medical care at the time; or after the flight; but may seek medical evaluation if it still bothered her today.Ground never issued us any traffic other than Aircraft Y that I was to give way to. My taxiway; 1W; veers approximately 30 degrees to the left (south) prior to intersecting taxiway G; so as to join taxiway B4 (after crossing Golf) which is a diagonal NE/SW leading to RWY 07. Taxiway G is North/South; so as I approached Golf any southbound traffic would be coming from behind our 4 o'clock position. He never became visible to me until he was in close proximity moving from my right to left.I am not certain which ramp Aircraft Z left from; but my guess is that it was far enough to the North that Ground gave him a 'taxi to RWY 25 via Golf and monitor Tower now on 128.75' just like us; never suspecting that he would race at 40+ knots down Golf and become a threat to us. I believe that the traffic was light and Ground was not paying close attention to aircraft moving around the West side. He never noticed that Aircraft Z was traveling so fast; and never advised him to slow down; or us to give way. If ground had switched him to tower when he joined Golf; as he did us; he had no way of controlling him if he seen the conflict developing in real time.Aircraft Z never slowed; and never made any effort to avoid us. I'm not even sure that he saw us; (can you even see taxi lights when approaching an aircraft at a high rate of speed from their 4 o'clock?). Going 40+ on a dark; moonless night required him to concentrate wholly on following the centerline. Had I not slammed on my brakes I firmly believe that we would have had a collision causing catastrophic damage to both aircraft (if not destruction of both aircraft in the ensuing fire); and huge loss of life.Ground was blaze about the whole thing; 'Yeah; I'm not talking to him'; like that somehow absolved him of responsibility. I don't know how close we came to colliding; certainly less than 100'; probably less than 50'. I believe that the Aircraft Z pilot was absolutely operating at an unsafe speed; and set up the near miss with his reckless behavior. He caused the near miss; and was unable to stop it once he set it in motion; as he was seemingly unaware of the pending collision. Ground also shares some blame for not actively controlling traffic in their sector. At the time they seemed unaware of the near miss; and once notified were very casual; sort of 'hey; no blood no foul'.Personally; I don't think anyone should be told to switch to tower until they are south of 1W; the Southern end of the ramp area; as aircraft can enter or exit Golf from any one of seven taxiways along the west side of the ramp. Also; when we got done informing ground about the near miss; we switched up tower on 128.75; as assigned. We taxied up and held short of Rwy 25; number one for Takeoff. After not hearing anything for a couple of minutes; we called tower and advised him that we were ready at 25. He gave us a very surly 'I've cleared you for takeoff; 6 times already'. He was working multiple frequencies; and had not given clearance to us on 128.75 previously. Perhaps controllers working multiple frequencies last night might have also led to some issues. I hope that they can pull the tapes and determine what rate of speed [that Aircraft Z] was traveling; and how close we came. Also determine if ground was in error by switching traffic to tower too early and not actively monitoring aircraft movement.




Synopsis: An Air Carrier pilot reported a near collision on a taxiway due to perceived Controller inattention and an aircraft taxiing at a high rate of speed.