Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Distraction; Time Pressure
Conflict Airborne Conflict; Inflight Event / Encounter Fuel Issue
Air Traffic Control Issued Advisory / Alert; Flight Crew Diverted; Flight Crew Requested ATC Assistance / Clarification
Environment - Non Weather Related
During vectors to ICN we got a delay due to unauthorized drone activity. Approach Control was unable to predict the length of the delay. We were at least the 6th aircraft in line being delay vectored. We evaluated our fuel and the number of aircraft ahead of us being delayed and transmitted Pan Pan to Approach Control for vectors to land at ICN. Approach Control would not vector us to ICN. They asked for our alternate airport which was ZZZZ1. We reported to Dispatch of our diversion and followed another flight diverting to ZZZZ1. We landed; parked and later departed again to complete the flight to ICN. This diversion was due to the unauthorized drone activity. No one had the ability to predict the length of the delay. The only known and the safest course of action was to divert to our alternate airport.
Upon switching approach control we could here holding instructions being given to aircraft.  We immediately began evaluating options for fuel and landing.  After being vectored for around 10-15 minutes Captain made the decision to declare minimum fuel.  The approach controller  responded that we were number 7 for landing at Incheon and requested our alternate airport.  We informed him that Gimpo (RKSS) was the alternate given a vector for approach.  Landing was uneventful.  Apparently there was drone activity near RKSI which prevented aircraft from landing.  Without any clear time frame as to when we would be landing and being number 7 for landing we made the decision to divert.  Don't really have any.  Can't control rogue drone activity.
Air Carrier Captain reported diverting to the alternate airport due to a UAV blocking traffic at the primary airport and holding fuel becoming an issue.