TSA’s “First Observer” training program is a voluntary program that provides transportation professionals with training on effectively observing, assessing and reporting suspicious individuals, vehicles, packages and objects.
https://www.tsa.gov/for-industry/firstobserver
It is a series of YouTube videos accessed via the link below.
https://www.youtube.com/playlist?list=PLXWway_rv-jVtdd02SaLcFxo3Rbxx7uho
While this is titled for OTRB drivers, it has SIGNIFICANT applicability to our transit bus operators. There are 8 videos with a total running time of approximately 82 minutes.