Date: 202002
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: IMC
Weather elements / visibility: Icing; Cloudy; Rain
Light: Night
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Airspace: Class B ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Anomaly: Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate; In-flight; Taxi
Result: Flight Crew Returned To Departure Airport; Flight Crew Took Evasive Action; General Flight Cancelled / Delayed
Contributing factors: Procedure; Weather
Primary problem: Weather

Narrative: On Day 2 of a 3 Day Trip; we experienced an irregular operation on our second leg; flight ZZZ-ZZZ1. The weather in ZZZ1 had deteriorated to sub-CAT 1; with low ceiling; low visibility and reports of moderate icing in the ZZZ1 terminal area. We prepared for an autoland approach to Runway XX. While established on the localizer just outside of the FAF; the preceding traffic reported that they had encountered severe icing on the same approach. We executed an early Missed Approach; climbed above the layers of icing conditions and requested delay vectors to evaluate our situation. After conferring with Dispatch via SatComm; it was jointly decided to return to ZZZ. We blocked-in to ZZZ at XA:58.Immediately following the completion of the Shutdown Checklist; I called our Dispatcher who said that based on several current PIREPS; icing conditions on the approach into ZZZ1 had improved from severe to moderate; and that we would be dispatched once again to ZZZ1 (we had received an ACARS message to this effect during our descent into ZZZ).However; as soon the L1 door opened (and while I was on the phone with Dispatch); the Customer Service Representative apparently announced that our flight had been cancelled. Passengers started to deplane... I relayed the information to our Dispatcher who confirmed that we would be flying back to ZZZ1. I made a PA to this effect; apologized for the confusion; jumped out of my seat and tried to inform those that had already made it to the jetway that we would be departing back for ZZZ1 once refueled.As has been my experience with past diversions; a few problems seem to reoccur: the flight paperwork cannot be retrieved; and the load manifest can take a long time to reconcile. This 'splash and go' took precisely 1h30min to accomplish!We finally blocked out at XC:28... While taxiing out at a slow speed (less than 10 kts.); I had to do an EMERGENCY STOP to avoid an airport operations vehicle driving at an estimated 40-50 mph southbound; outside of the vehicle road; rotating beacon flashing and headed right for us. Close call and narrowly avoided collision there! This vehicle had not seen us; made an emergency stop followed by a 180deg turn and stopped.Our flight to ZZZ1 was uneventful and concluded with an autoland on Runway XY. We blocked in at XD:37. Thanks to the ZZZ1 station contacting our hotel; transportation arrived promptly. I went to bed at XF:00.Our morning Report Time was adjusted to XN:52 for our departure to ZZZ. We got de-iced (it was snowing) and flew back to ZZZ.Upon arrival after an uneventful flight; my F/O and I had a discussion about fatigue. We had both slept about 5 hours; had woken up and tried to sleep more... We decided that it was not smart to continue our day as planned: a flight to ZZZ2; close to 3hrs of ground time; and then ZZZ2-ZZZ3.Our fatigue call was the result of an unforeseen irregular operation and didn't have much to do with pairing construction. We had pushed ourselves hard during our second flight to ZZZ1; which concluded by an autoland in low IFR on a contaminated runway with potentially adverse icing conditions on the approach. It all worked out because of careful planning and execution; well passed our normal bedtime...




Synopsis: Air Carrier Captain reported fatigue after a challenging duty day involving weather and an air turnback after destination airport reported severe icing.