Originally Posted by
rickair7777
It's nothing like millions for a new-build airplane. It also would not be millions to retro-fit, although that would cost more than new build.
I don’t recall saying “per airframe.”
Common gross conceptual error for non-military folks is the thinking that any defense with less than 100% efficacy is a waste of money.
oh good, we got to the condescension part already.
It's not. The opposition (including terrorist groups with the means to attempt a 9/11 style hijacking) always considers risks and obstacles... they do not like to throw hail mary's because failure is bad press, and tends to de-motivate their funding sources. So throw enough partially effective obstacles in their way and sum total of that is enough to severely discourage them. No fly lists, agressive counter-terror on the part of intel/law enforcement, TSA, improved procedures, FFDO, barriers... it all adds up to a lot of swiss cheese with few holes. Barriers are VERY high efficacy for actually very low cost... compared to all of the other mitigations I mentioned
Each layer of Swiss cheese should actually cover a hole not covered by other strategies. I’m not convinced secondary barriers do so in a post-9/11 world.