From the Wine Swilling Lawyer (the latest version I’ve seen) —:
…Components of IEDs [improvised explosive devices]can be smuggled on to an aircraft, concealed in either clothing or personal carry-on items… and assembled on board. In many cases of suspicious passenger activity, incidents have taken place in the aircraft’s forward lavatory.
There is a real simple solution to this. Put big assed hasps on the lavatory doors. Buy big asses padlocks. Put the key to said padlock in the locked cockpit. Put said lock in the flight attendant’s pocket.
When jackasses start pulling this crap, slap that lock on the door. Once the plane is on the ground and everyone else (like his accomplices) is off the plane (and in custody, if need be), he can greet the FBI HRT and explain to them what the things there in the bathroom are for.