Date: 201911
Local time of day: 1201-1800
Location: AUO.Airport, AL
Flight conditions: VMC
Light: Daylight
Aircraft: Small Aircraft
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Taxi
Airspace: Class D AUO
ATC / advisory: CTAF AUO; Tower AUO
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown; Situational Awareness
Anomaly: Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Incursion Taxiway
Detector: Person Other Person
When detected: Taxi
Result: Flight Crew FLC complied w / Automation / Advisory
Contributing factors: Airport; Procedure; Human Factors; Chart Or Publication
Primary problem: Human Factors

Narrative: I have flown a lot in this area; and am familiar with the airport. Given that it was a beautiful VMC day; and a very short and straightforward VFR flight; I did not obtain a full briefing; however; I did go on Foreflight and looked over the route. I noticed a TFR for a nearby college football game; but saw that it would not go into effect until well after I departed. I had not yet flown into this airport on a game day; but didn't give it a second thought since the TFR wouldn't affect me. I did open the airport info page on Foreflight; and saw a NOTAM listed that one of the two runways would be closed. I conducted the flight; and it was perfectly uneventful. Upon nearing the field; I listened to the AWOS; and it mentioned a NOTAM that one of the runways would be closed for game day parking; but other than that; nothing unusual. There was a little traffic; but everyone was communicating well on the CTAF; and I made a normal landing; and parked at the FBO; since I would be gone before the game. After returning from lunch; we loaded up in the plane; and I listened to the AWOS before departing the ramp. The AWOS again mentioned the NOTAM for a runway closure; but that was the only unusual item. I announced my taxi intentions; and began taxiing to the runway. I had almost made it to the runway; when the FBO contacted me on UNICOM and told me I needed to contact Ground. This greatly confused me; as I had flown into this airport before; even just a couple of hours before; and it had always been a class G pilot controlled field. UNICOM informed me that they had a temporary Tower set up for game day; so the airport was now class D; and it was operating Ground and Tower frequencies on a separate frequency from the CTAF. I contacted the new ground frequency; and they gave me taxi instructions; then Tower gave me takeoff clearance; and I made a normal VFR departure. The Controllers did not mention my mistake in taxiing without clearance; and gave me no grief over the incident. Ultimately; I am responsible for this incident as I did not conduct a thorough enough briefing. Had I done a full briefing; I probably would have noticed this NOTAM. That being said; I feel like the way this is set up makes for it being a potentially common mistake for the following reasons: The EFB listed the NOTAM for the runway closure; but not the temporary Tower/class D status. Somebody would have to receive a full briefing to find out about this one. This is the technically correct thing to do; and what I should have done; but realistically speaking; not everybody in GA is going to be getting full briefings for VFR flights on perfect weather days. Perhaps the biggest issue is that the AWOS made mention of the runway closure; and even gave taxi instructions to arriving aircraft; but did not at all mention the existence of the temporary Tower or change to class D status. The AWOS giving taxi instructions to arriving aircraft makes it seem even more unlikely that there would be a Ground Controller working. This may be perfectly normal; I don't know how these procedures work; but it did seem a little strange that both the Ground and Tower Controllers were operating on frequencies other than CTAF. Any arriving aircraft that had not received a full briefing would naturally listen to the AWOS and then transmit on CTAF; which means the only way they would avoid a potential incursion or incident would be the FBO notifying them on UNICOM; if they were paying attention.




Synopsis: Small aircraft pilot reported failing to contact temporary Tower resulting in taxiway incursion.