What changed after that event in the passenger security check, before
entering in the restricted area?
Virtually nothing changed. You were still asked the 3 key questions you are asked today, Did you pack the bag? Has the bag been out of your direct awareness since you packed it? Did you pack anything you shouldn't have?
The difference is that whereas before if you said no or I dont know to any of the above questions, they went through your bag. Now, regardless of what is said, they will probably cut your locks and go through your bag.
Since 9-11, a lot more of your stuff gets stolen before the bag makes it to the plane, and there is nothing you can do about it.
Could be possible now to enter in an airplane with a knife and/or a
Yes, there are actually a bunch of people that have done this over and over just to make a mockery of the TSA.
Before 9-11, you walked through a metal detector, and then you waited. If you set off the metal detector, you might get patted down.
Now, you have to take off your belt and shoes, you have random odds of "enhanced pat downs" based on "random number generators". If youre super lucky, the TSA takes you to their special hidden room for an enhanced security check (Sky Harbor has a doorless underground room for this.)
It's a whole crap ton of hassle and privacy invasion, but you can still hide a knife bundled in something in your bag, and the xray scanner wont get it. Even with the full body scanners, ANYTHING can be hidden in a fat roll.
All that hassle, no real gain.
Was the hijacking possible for some errors in the security system, or it >simply wasn't reliable enough to avoid a hijacking?
It wasn't an "error in the system". Stop war. Stop murder. Stop violence. You can't. People have tried since the dawn of man, and there is just no way to stop it.
The TSA is an act of paranoia. Those who are hyper paranoid and afraid of the world enjoy the inconvenience because they feel like they are trading freedom for security. In reality, they are trading freedom for a placebo.
We are no better off in the airport than we were pre 9-11, it just takes 5 times as long to get through the airport, and it is now an often humiliating and angering experience.