Date: 202102
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Small Transport; Low Wing; 2 Turboprop Eng
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Taxi
ATC / advisory: Tower ZZZ
Reporter organization: Personal
Reporter function: Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor
Human factors: Communication Breakdown; Confusion; Distraction
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Incursion Runway; Ground Incursion Taxiway
Detector: Person Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Provided Assistance; Flight Crew Became Reoriented
Contributing factors: Environment - Non Weather Related; Human Factors
Primary problem: Human Factors

Narrative: I listened to the ATIS and prepared to taxi out for the short flight from ZZZ to ZZZ1 in the new to me aircraft. We had come in a few hours earlier and had no adverse radio issues at all. Reviewing the NOTAMs earlier I had filed away that the Tower was on part time status; most likely due to COVID; and would be closing in the afternoon.After startup we called Ground and did not hear a reply. On our arrival they had told us to stay on the Tower frequency; so we tried that one. Still no response and we tried each a few more times.We listened to the ATIS again and noted that it talked about the Tower closing and that it was many hours old. The passenger in the right seat was also a very experienced ATP rated pilot and CFI and he told me 'The Tower is closed'. I remembered that possibility from my NOTAM search earlier in the day and asked him how he knew. He said it was on our Foreflight app and he heard XA30 on the ATIS.That seemed plausible to me; so we reverted to CTAF procedures; announced our taxi on the Tower frequency; and proceeded to Runway XX. I did glance up at the Tower; just in case; and saw no light gun signals but the Tower was soon out of view. Part way to the runway we were intercepted by an airport vehicle and the driver pointed to his radio. I switched our radio to the second nav/com and was able to establish communications with the ATC facility.In retrospect; this was a good example of a display of expectation bias. We fit the facts we were experiencing into the theory we had developed for what was going on and we were mistaken. I knew that when a Tower closes they say so on the ATIS broadcast; but being so old I thought maybe they had just forgotten to do so. We both had XA30 in our minds as the closing time and discussed that it was now XB30; but we missed the fact that on the ATIS and the NOTAM XA30 was the opening time and it was UTC; not local time. The radios worked fine on the way in; they must be working fine now; etc.In reality we were wrong on all accounts and it is a good thing that we were able to establish ATC contact before taking off which would have only complicated things for all.




Synopsis: GA pilot reported thinking the Tower was closed; started to taxi to the runway and was stopped by an airport vehicle who pointed to the radios. The pilot contacted the Tower before takeoff.