Date: 201901
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Aircraft: Medium Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Workload
Anomaly: Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Work Refused; General Flight Cancelled / Delayed
Contributing factors: Environment - Non Weather Related; Company Policy
Primary problem: Company Policy

Narrative: Upon preparing to depart for [a destination in Mexico] the First Officer and I noticed an advisory in the notes section of the Dispatch Release talking about volcanic cloud near the destination. It was a partial snippet in the notes section and not the full advisory which is difficult at best. Upon seeing this; I reached out to the Dispatcher to get clarification on what it was and it was supposed to terminate and be a non-factor around that time. However; an update was due and upon looking for the update; it was found that the cloud had been extended for another five hours. The volcanic cloud advisory was within 6 miles or less of the airport or so. The Dispatcher initially said just land south and you should be good only a 5 knot tailwind. Also; it was mentioned that the Tower is good about telling us what they see. (This also was comical as not sure what type of clouds the Tower can see at night). Even top tier NVG's would have had trouble seeing this. We hung up with Dispatch to discuss this more as neither of us really felt comfortable with the current push and assessment.  We both spoke with other trusted sources to include On Call Chief Pilot and several check airman and safety folks. We all determined that at night with an advisory this didn't sound like a good idea as well as not having an option for a go-around without flying into a possible volcanic cloud in mountainous terrain. Volcanic cloud; possible ash; extremely close to airport; no good volcanic guidance in FOM; no go around option. Tailwind landing at night at high elevation field. Oh and did I mention the volcanic cloud.The first error should have been trapped by Dispatch trying to Dispatch us at night near volcanic clouds which we can't see. Several other airlines have a 'not at night' policy with advisories of this nature meaning they automatically delay until daylight or cancel. Second is when the update came out it should have been an immediate re-evaluate and assess the risk. This took the crew to throw up the 'wait a second' sanity check. Lastly; the fact that the FOM has zero guidance and only mentions to file a report and let ATC know if you encounter volcanic ash. The initial thought of land to the south with a tailwind to avoid the advisory area is very poor decision making. Had this been a different crew they might have put themselves into a very dangerous situation. Overall; the company needs to have better guidance for Dispatch as well as available to the pilots.




Synopsis: Air carrier Captain reported refusing to fly a planned leg into known volcanic ash area at night.