The Israelis seem to do a pretty good job of keeping their aircraft safe. Why don’t we learn from them?
They do behavioral profiling. They look at whether they change clothes or shave while traveling, abruptly change direction while moving through the airport, sweat, tremble or blink rapidly during the flight, use their phones, talk to other travelers or use the bathroom, among many other behaviors. They also do extensive interviews, looking not necessarily at the answers given, but how the answers are given.
The Israelis make a whole bunch of completely unacceptable assumptions. For example, they assume that Islamic travelers aged 15-45 are more likely to be Islamic terrorists than, for example, Christian infants or elderly Jews are. We're too politically correct to be sensible.