Thank you for the post. I had no idea about the kick strip-triggered alarm.

I'd certainly have enquired if all was OK if I ever noticed the alarm going off, and if not, I'd have called a member of staff and emergency services if applicable (obviously not if someone's plain trapped there rather than being ill), but it is useful to know what it sounds like so if I hear something unusual, I'd know what it is more quickly now. I do hope I have never unwittingly failed to notice the alarm going off.

It may be a good idea to have a flashing alarm there as well though, so that it is easier to notice. With the airport being full of sound and noise, it may get easily overlooked if it's just the subtle alarm sound, whereas an illuminated sign saying "Help required" with a flashing red light at the disable loo combined with the audible alarm may well draw people's attention much better.