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I take your point, there is a bit of self interest when the decision to bandbox is required but I'm not sure keeping sectors open to reflect the PSS is the right solution for a couple of reasons.
Firstly, and this is the self-interest bit, alot of ATCOs use their breaks for admin purposes, reports, rosters, leave books, etc not to mention the debriefing of trainees which can take a big chunk out of 30mins.
Secondly, keeping sectors split to reflect the PSS implies the ability to keep sectors bandboxed also as per the PSS, which we both know is a leap of faith too far.
I realise that your proposal is to illustrate a point rather than provide an alternative way of managing the staffing and that we both agree that the essential problem is lack of valid ATCOs. I don't think we can improve the situation from the shop floor until numbers rise.