It’s an aid - sometimes. But seriously unreliable.
I’ve seen coastal rescue helicopters fly past me along the coast, well below 400ft , who’s presence just didn’t exist.
Chances are, that they were so low, was a contributory factor in them not appearing on ADSB.
Someone else reported the same on GADC some months ago - including the track that showed it went into stealth mode.
Not my experience - It’s been absolutely massively, ridiculously, 100% accurate - to the point where I can confirm an aircrafts location visually compared to whats shown on ADSB Exchange - and I check even when I’m not flying.
That’s fine.
But when one isn’t on ADSB - and I can absolutely guarantee that this has been the case - it’s less use than a chocolate teapot.
And that, my friend, is a fact I’d be happy to swear to in court.
Here’s the post to which I referred - complete with the (lack of) ADSB track.
Not my experience friend. 100% accurate in my opinion, I wouldn’t peddle this opinion otherwise.
I even went to chat with an Air-Ambulance crew when they landed nearby based on ADSB data
Love this thank you.
I fly a MM. I’m a hobbiest. I take for myself interesting photos and occasionally share them.
I have taken the basic competency test and registered.
I fly within the code and where I don’t it is not intentional and always safely.
I don’t need drone police to jump up and down every time I post a non compliant photo. I need encouragement and guidance to enjoy my hobby more.
Thank you, I love Grey Arrows.
I don’t want to be disparaging, rude or mean.
I’ve been monitoring the aircraft in my local airspace and beyond for quite some time now, and have found ADSBExchange to be 100% accurate.
I live in an elevated position, one of the highest in the NW and am able to visually observe aircraft for a hell of a long way from my top floor and have repeatedly, visually, confirmed data from ADSBExchange to be bollock-clangingly accurate.
I admit, I get massively annoyed when people dismiss online ADSB services as ‘useless’ or ‘innacurate’ and therefore discourage people from using this massively useful resource.
However, 500m LOS is NOT law.
Happy to be corrected.
Or, is it Mrs Bacon, in the kitchen, with the candlestick?
Nobody has said that it is.
I most certainly have not said that it is. Quite the opposite.
What is your problem?
VLOS varies with size of the drone, weather conditions , light and the colour of the drone. A mavic mini you would probably have trouble at 200m and an inspire probably a hreater range. That is asumeing no additional lights are fitted. I have had my mavic 2 pro to 1400m with ligrhts fitted and maybe further. So there are factors that can effect LOS
Without doubt.
I can see the Inspire over a mile away, and look down at the screen, then look up and STILL see it 
I struggle to see the Mini at 20m out, never mind 200 
Moved your post over to a relevant preexisting thread. There so many examples we could fill a dedicated forum with them. 
Thank you for doing that 
We all probably feel a bit like this at times. Sometimes it’s just a case of suck it up buttercup as it’s not worth the hassle of pointing it out, and you’re the one that ends up the bad guy.
On the bright side karma will hopefully get them.
Shit I know.
If you chose to inform the rozzers, do it anonymously or don’t make it public you have as you never know what repercussions there could be, but that is your choice at the end of the day.
Pisses me off sometimes as well😤
I was calming down after your first post… now I’m pissed off again! 
Wasn’t even aware that the MM could go that high. FW mod?
I guess so - my MM is capped at 120m (400ft).
Just been on “the other US site” and new comers are always asking about regulations in the UK. The information is always given about what you can/can’t do but then they go and show a video entitled “Welcome to Nottingham City Centre” flying over all the buildings and railway lines !!!
How about if you feel strongly about this and know where they live, put a note through the door pointing out their transgressions. Maybe direct them to a website showing the drone rules or even here?
It can be done anonymously if you wish, because some people may not take kindly to having things pointed out to them.