It's the question that has sent many a bleary-eyed Derry person to social media late at night after being woken up by the sound of helicopter rotors in the sky above - 'Why's the chopper up?'
People in the city can now take solace in the fact that the issue does not only affect residents trying to get a good's night sleep in Derry, as it seems that people living in other areas across the north are also concerned about being kept awake at night.
However, the PSNI has now hit back at those complaining about the noise made by the chopper in the night skies, telling people that they should be 'thankful' that the police helicopter was assisting families who have may have been targeted by criminals, or helping in the search for a missing person.
"They aren't just up for a laugh, they aren't just up to annoy you and keep you awake. If you find them up late at night again and don't know why, be thankful it's not you who has a loved one missing," the statement posted on social media read.
"Be thankful it's not you who's had their car stolen. Be thankful it's not you who has been burgled. Or, if you've been up to badness, be worried."
The statement added: "When we attend calls, we ask for whatever resources we deem to be most suitable. Sometimes we get them, sometimes we don't.
"Missing people, stolen cars, burglary suspects on the move, pre-planned arrests we want the eye in the sky for to make sure someone doesn't bolt...all of the above are reasons why the chopper may be up.
"In addition to that, they have routine patrols which they carry out. Put yourself in the shoes of a burglar. You're out looking for vulnerable victims, and you see the chopper overhead. What do you do?
"It won't surprise you to know that we don't get many burglary reports while the chopper is out!
"In short, if you can't sleep, too bad. Our eye in the sky is up carrying out police work, as are the cars you see, the beat patrols you see, and the check points you stop at. They aren't just up for a laugh, they aren't just up to annoy you and keep you awake."
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