If you get 100 Security experts and asked them what was their biggest problem, I would be surprised if it was not all 100 saying the single suicidal person.
Extreme I know, but ALL air lines, the Senior Cabin Crew should man the flight deck if a Pilot leaves the cockpit and be trained to at least PPL standard, and door opening
As SLF I rely on the fact the Pilots have a self preserving attitude, and bus, train, lorry, drivers etc ..... the one KamiKazi(sp) cannot be eliminated
A cousin committed suicide and at the inquest a Female that no one knew came and said she had a affair with Cousin and he was afraid he would loose his kids if it came out!, totally screwdup