then those in the planning department should be culpable
I suspect it's not any of their business. A planning application must be granted unless there is a good reason in planning law to refuse, and a planning officer saying "well, I don't really know anything about aeroplanes, but isn't that a bit close to an airport?" is not, I'm afraid, going to survive appeal or judicial review.
Any "safeguarding" process (yes, I've seen some such maps, but only in relation to CAT, not SEP GA) must surely be the responsibility of aviation professionals, not town planners?