Many thanks for the reply Tim. I completely understand that a large proportion of this information is unofficial and so it must be a large task to manually gather and record this into SkyDemon. I know that many users at Biggin have found this depiction of the areas massively useful to quickly determine, in flight, where these areas are rather at a time when eyes are better served outside the cockpit! I'm sure countless other airfield users have similar experiences. 

I wonder if airport operators can be encouraged to incorporate these requirements into their AIPs? To me, it's as much a safety issue as an environmental one and if it makes adding these to applications such as SkyDemon easier, then everyone is a winner!

I'll ask your customer services the same question. 

I do know that recently we discovered that there were various so-called noise sensitive areas specified at long distances from airfields. We began work to remove many of these that extended beyond distances that we thought were reasonable. The exception to this is where such areas are specified in the relevant AIP.

.....and for comparison here is the Airport's chart and the current SD chart.

I fly from Biggin Hill and we have a number of NSA around the airport that we are asked to observe. Skydemon has always been a fabulous help to pilots to understand where these are, as with many other airfields that I fly into. This helps enormously to not upset the airport operators and neighbors. 

However, I have noticed recently that the Biggin Hill NSAs had partially disappeared, particularly the ones outside the ATZ. I have just had a chart update and now most have reappeared and a number of others (not notified by the airport as far as I am aware) have appeared! There remain some others that are still not shown in SD. 

I know this info is not "official" in that it is not in the AIP, but where does SkyDemon get this information to display these areas? I suspect the Pooleys guide as I can see an area truncated in shape as it is by the page margin in the Pooleys guide yet the area extends further North on the Airport's own drawings. I understand that these are 'unofficial" pieces of data and it is a great courtesy that SD have chosen to display this info and is in no way obilged that this info is correct! Just curious as to how these differences are cropping up.