Small Transport
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Confusion; Distraction; Situational Awareness
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Human Factors
This was day 2 with a brand new FO but it was the FO's first day doing a preflight as we started flying the day before after I had an FO swap part the way through the day.  I did the flight planning the night before and had a few conversations with operations about possible passenger catering (that turned out to be an old note) and customs payment arrangements at this airport.  I had read 'ZZZZ' on the trip sheet before getting to the hotel and somehow my brain registered that as 'ZZZZ1' and not 'ZZZZ.'  When I entered my flight plans the night before I instinctively typed in 'ZZZZ1' into [app].  I made sure to get up early to print out all the international paperwork and all other necessary paperwork before we left the hotel so I could devote my full attention and time to the preflight inspection lesson as well as getting the raft in the morning.  After going through the full preflight together; we got the clearance to ZZZZ1 and departed.  Shortly after taking off we were given 'direct destination' by ATC and we did so.  After being given a frequency change ATC again cleared us direct destination.  I stated on the radio that we had already been cleared direct and were proceeding there.  ATC then stated our track was taking us over ZZZZ2 and I zoomed out on the INAV map and saw that ZZZZ had accidentally been entered as the destination instead of ZZZZ1 per the flight plan.  I changed the destination to ZZZZ1 in the FMS and we started flying to the airport.  Just as I did that; however; my FO mentioned that ZZZZ1 was not the airport that was on the trip sheet. I looked; and FO was correct; I had mistakenly filed the flight plan to the wrong airport.  We got an amended clearance from ATC and preceded to ZZZZ.  I called ZZZZ2 radio enroute to get weather and NOTAMs for the new airport and verified our fuel status would still be safe.  We landed at ZZZZ without incident; picked up our passengers and then returned to ZZZ after I refiled the return flight plan.  I can only think that unnoticed built up fatigue from the days before caused the error filing the flight plan.  I started my cycle out west so I transitioned a few time zones and overnighted at ZZZ1 the day before the FO swap causing a long drive to and from the hotel.  Home life has also been stressful; as I have had a few COVID-19 scares with my immediate family.  Since I thought fatigue could be a threat; I decided to stay in ZZZ that night instead of doing the empty repo to ZZZZ2 as originally planned.
Air carrier Captain reported filing the wrong destination and not realizing it until the FO advised they were going to the wrong airport.