Thinking out of the box here, and that have its consequences. (Running on strong meds, sleep deprivation, and on med leave with lots of time to think. Forgive me if this is ridiculous.)

Can the old puffer technology, adapted differently in a more controlled environment, be used at the time of boarding? Once the plane is full and the doors are closed. Circulate air and do an overall plane explosive detection. If the whole plane passes, kick it out of the gate and let it go. If not, re-screen. Gigantic PITA but it may be very rare. How often do the carry on ETD check actually show explosive?

Has this been tested and looked at? Short answer please, no technical explainaintion necessary. As in, tried it, did not work. Showed too many false positives. Whatever.

This, combined with WTMD, would be simple, if it worked. Just looking for answers. Not that they care.