I used to think that long queues at security were generally the result of slow, inefficient or ignorant pax, with liquids undeclared, or unpreparedness in removing coats, etc.

But increasingly, I see that I was either wrong, or things have changed..

The delays when I see them, seem to be in the x-ray machine, with slow passage of bags/trays through the scan. This leads to pax at the start of the machine having to wait for a 'space' on the conveyer leading into the x-ray. If you see what I mean.

- I wonder, therefore, if there has been a change in recent months on the processing that is done during the x-ray scan. Different filters/different scan settings, etc.

One of the interesting things I learned from a family member who does work in this area is that the x-ray software does randomly overlay suspicious items onto the image of bags. The security officer at the terminal has to spot these, and press a button, to alert/dismiss the overlay. Some of these images are complex, and hidden. (They're not all gun-shaped!) And so this can take time, as the officer doesn't immediately know it's a dummy imprint, and has to process in accordance with training. Different scan 'windows'/filters, etc.

This is pure speculation, but perhaps recently the frequency of these in-work training/audit images has increased, or become more difficult, slowing the whole process down? Hence, the occasional observation of several security officers clustered around the screen.. apparently 'chatting', but perhaps discussing a complex image?