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.