Part 107 UAS Chief Pilot reported one of their UAS pilots flew within an active TFR without authorization. The TFR was created after pre-flight checks were done. Once the pilot became aware of the TFR; they ended the flight.

Narrative

On Day 0; at approximately XA:32. One of the operators for our company was conducting pre-flight planning for several UAS missions approximately 6 Statute Miles northeast of MDW airport. When they reviewed the airspace authorization; there was no Temporary Flight Restriction (TFR) in place at that time. At XA:45 a TFR was put in place for the area including the airspace where our UAS Operator had planned their mission.From XC:15 to XD:16; our operator conducted several flight missions; totaling 35 minutes of flight time under the active TFR. There were no incidents during any of the flights and the pilot safely and successfully returned the UAS to its takeoff location without incident. Since the TFR came in place after our operator had conducted their pre-flight planning for the day; they were not aware that the TFR had been created for the airspace they were operating in. Once they discovered that a TFR was in place; they immediately ceased flight operations and reported the incident to me as UAS Program Chief Pilot.Our corrective actions will be to make adjustments to our Pilot/Operator training to include a re-check of airspace authorizations immediately before flight; as well as making adjustments to our internal Flight Planning App to remind our UAS Operators to re-check any flight authorizations/airspace restrictions before taking off.