Howdy from the "old man" 8)
"As Bruce pointed out this morning on NPR there are methods that the scanners won't find"
Yup I posted one such method (a bone knife and pig skin and fat) oh shortly after the 9/11 and body scanner issue started many years ago.
And these basic issues have not been solved all the new scanners do is hope to spot that such things are out of accepted physical alignment with the average anatomy of a human...
Which admittadly makes the hidding issue considerably harder for "jo/joe Average" it does not make it much harder for some one with quite basic field trauma / surgury knowledge and a handfull of pain killers.
There is of course another issue of what do you do when the system fails what are the procedures.
That is can a terrorist inject themselves with fairly readily available tomographic dyes to game the system by making their body sufficiently different to fool the system or the operator or subsiquent procedures.
Then as you note there is the very thorny issue of
"... airports where they can be bypassed for not being installed."
Recently a former senior in the DHS was interviewed by the UK's BBC Radio 4 Today program. He sugested that it was OK to get other non US countries to bare the cost of installing such equipment in countries who could not afford it to protect US airspace...
Apart from the rather stupid attitude of "you pay for our mess because we say so" there is a much more important issue od "national security" does for instance the US populus want to have it's close in airspace effectivly controled by the Communist Chinese?
And you then go on to the real pay dirt,
' "The screeners are there to support their machines". It should be the other way around.'
Exactly the real issue.
Now to throw a spanner in the works of conventional thinking.
1) As humans are involved as both the screeners and the screened each side has human failings.
2) Human failing can be observed by others at all times.
3) If there are no penalties involved then you can go from observing to testing with little difficulty or risk.
4) testing allows ideas about human and system failings to be charecterised.
5) Once the charecteristics of the system are known if can be evaluated for weaknesses.
6) Any weaknesses found can then be tested and charecterised to alow the system to be successfully gamed.
So you can see how a reasonably insightfull and introspective thinker could in little time find out how to bypass the entire security system with little difficulty.
Infact we saw this with both Cptn Underpants and Cpl Hotfoot, both used methods found by others testing.
There are two solutions to this testing issue,
A) make the process too expensive "to enumerate" by having significant penalties.
B) Design the "flight screening" system such that an observer can never get sufficient information to get a probability high enough to make an attack effort worth while.
Why do A&B?
Well next time you go through an airport and see the bins and boxes full of "contraband" ask yourself how many of these are "failed enumaration" attempts by terrorists etc?
The most valubal resource to a terrorist or criminal organisation is "grey matter" in it's planning operatives. And like common sense it is actually quite rare and thus very valuble to any organisation.
So with regards to (A) penalties for trying to "enumerate" the "flight screening" process,
If you had a very clear and open list of what is and is not a contraband item and made it clear that the penalty for a first offence regardless is "you don't fly today and your bio-metrics and other details are recorded, your passport will be marked so that you will always go through full screening for a minimum of a year. And importantly you will go through a full background security check for which failing is a life time on the "no fly to/through the US list".
It would have a significant impact on anybody who gets caucht in the "flight screening" process.
However it should have a "protect yourself against yourself" system (free or moderat cost of say 20USD in todays value).
That is you arive at the airport and put yourself through a self check screening process before joining the rest of the people for actual "flight screening".
This "protect yourself screening" can be run by a simple question and self check / ask process and not require scanners of any kind just knowledgable friedly and helpfull screeners. Who if there is any doubt can quickly escalate an enquiry to a satisfactory conclusion with minimal issues (ie the item is put in hold lugage or other metod of transportation).
Also any enquires you have can be recorded so if you are told "that's ok" by a screener there is no penalty if that is not the case.
Thus the cost of not self testing in advance is quite high, but low for those sensible enough to get assistance on the self check, and importantly takes the risk out of "flight screening" for honest people.
And because the system is Open if a person breaks the rules they have only themselves to blaim...
However the cost to those trying to enumerate the "flight screening" for whatever purpose (drugs / terrorisum / etc) is very high in that they become "known" and they know it will entail a detailed background check...
On a second offence you get an automatic jail sentance of 1 month and a criminal record and 1 year on the no fly to/through the US list.
Again you have no one to blaim but yourself, the self check process is there for all.
If however you are picked up and your bio-details are found in the DB and you now have different details and no legal reason to do so well "bang orange jumpsuit" and off you go to Cuba or where ever.
This might sound draconian but apart from the orange jumpsuit and open air Cuban accomadation is what you will find in various places world wide for Drink Driving.
So onto (B) making "flight screening" difficult if not impossible to enumerate.
If you think pack to point (1) about human and procedual failings, these are two of the three things those enumerating the system want to know. The third is will the system pick up my "contraband".
Well the solution is belive it or not randomly failing people through the process.
That is you have a heiracical screening process from a simple walk through metal detector to a full internal scan like an MRI...
As you go through the quick tests some people will fail (for whatever reason) and some will pass.
Now if the system is such that your boarding card/badge is scaned at each point and the system (ie not the operator) provides a go / further check answer passengers either get through quickly or get further and further checking untill assumed clean or proven to be holding contraband.
Now at each of the early tests the system also randomly makes "false positives" those people then go on for further more detailed or time intensive scanning.
Nobody knows untill a finall full system if the person concerned has a contraband item or is just randomly being checked.
Now providing there is sufficient capacity and the checking is done sufficiently in advance of gate closure time the system will be fully occupided without risk of falling into "que issues"
The upside of such a system is it is not the operators who make the choice of people to more fully screen or not but the system. So that should remove any bias they might have. Further seeing people get pulled for more detailed screening will actually build confidence in the system (false positives to extra screening are only minorly anoying to those it happens to provided the process is clear and open). That is an overly responsive system is seen as better than an under responsive system.
The important point is that for a person trying to test enumerate the system they do not know what the triger points are for the early or intermediate screening procedures are, thus they do not know the sensitivity of the systems, and thus cannot enumerate the system without significant risk of being caught.
Being caught is a night mare for them due to the full background check and recording of bio-metrics etc. The chance that a reliable agent will get caught is high which as they are generaly a scarce resource a significant attrition. Likewise using low grade people will with the background checking cause their recruiting process to be enumerated by the authorities.
Lastly get rid of the need for "carry on". However don't do it in a way that is seen as "profitering" that is alow people to buy food and drinks to take onto the aircraft after "flight screening" at sensible low rates, thus they have little incentive to take bottles of water snakes sweets etc etc through as carry on.
There are other asspects to do with business travelers and their laptops etc but this post is to long already.