Since when have airlines such as Atlantic Southeast Airlines (ASA) been required to screen passengers with metal detectors and baggage scanners? The reason I ask is that the first time I flew on one of their EMB120s (I think it was around 1992ish) from DFW to Lawton, OK, I don't ever remember having to pass through security. In fact, ASA was at terminal 4E (now just E) using gates (approx.) 1-4. One could get to the airside at those gates but would have to clear security to enter Delta's gates.
Then after a series of crashes involving commuter turboprops planes, the commuter industry was compelled to comply with FAR Part 121, so I'm guessing that's about the time that screening began on commuter planes, but I could be wrong. Could someone please enlighten me?