Part 107 UAS pilot reported flying for a short time without LAANC authorization. Pilot obtained authorization and continued the flight.

Narrative

I was at the park in City X. I was intending to use my drone to film a youth football game from about 50 feet AGL. I arrived and preflighted my drone; then the game started so I took off and began filming at 50 feet AGL. About 5 minutes into filming; I realized that I had forgotten to get LAANC authorization. The zone I was in was ZZZ class D airspace with automatic LAANC authorization up to 400 feet. I quickly opened my AutoPylot app and got authorization for my location; time; and altitude; then continued my mission with no problems. In the future; I will prevent this incident from happening again by ALWAYS checking the AutoPylot app before I fly to confirm which airspace I am in; and always getting LAANC approval before I fly if it is needed. I will also add this airspace check and LAANC approval to my preflight checklist every time I fly. I believe the factors contributing to this were human error; as I was rushed to get my drone up in time to film the game and forgot about LAANC initially. Luckily I caught my mistake; but in the future I will be much more careful not to make this mistake again.