Originally Posted by
s0ssos
So it beeps. And then? You magically have a wall where you cannot proceed?
How exactly do you mean "denied boarding". The system physically prevents the person from getting on the plane. By what means?
That's the GA's job. Most GAs will not let you board until it lights up green / OK to board (because that is literally their job). If you try to proceed to the jetway before it is green / OK to board the GA may put their hand to block your way or do other such gesture, and if a pax proceeds without being OK to board it's their job to chase you down the jetway and get you off the plane. That is the whole point why the boarding is manned.
In more developed airports (i.e. outside of US) there are often gates where you scan your BP and the gate opens, so if not physically manned then yes, there will be gates that open and only let one pax through, only after BP is validated.