Latest copy of one of the popular aviation periodicals has a report on an organised spotting trip to North Korea! (yes, I was surprised too).
Won't this get you a 10 year sentence after a three-day trial for spying? And no, I'm not joking.
I know quite a bit about DPRK. The place fascinates me. In particular how they deal with Westerners on official tours fascinates me.
To get a visa to get to visit (and many, many Europeans and Americans have in fact visited over the last 15 years whose accounts I've read), you need to agree to what they tell you to do.
You will be met by official escorts at the airport, you will not go wandering off on your own, you will stay in the hotel they tell you to stay in (at the rates they set), you will eat what they tell you to eat, when they tell you to eat it (as tourists, you will get very, very good food), and you will follow the itinerary they give you.
You will surrender your passport to them on arrival, and your first duty will be to pay respects to "The Dear Leader" and "The Glorious Leader". Accounts of this ceremony all involve you buying some flowers, and at least bowing to the statue of the dear leader, if not crying as your chaperones most likely will.
You do not get to take photos of anything you want. You do not get to make phone calls to whoever you want. It's their country, you're their guests, you do as they ask you to.
Remember: they have your passport. It's probably polite to do as they ask, and they will return the politeness by returning your passport at the end of your trip. It's not a
threat, per se. Just an
understanding
If you turn up wanting to do some plane spotting, either that will have been agreed in advance and they will tell you where you are going, when, and what planes you will see, or you're making up an itinerary on the spot and your request will be politely refused.
You will not get to see any military hardware, and if you should see it by accident, you will be not allowed to take any photos of it on pain of your camera being destroyed and you possibly being imprisoned.
There have been people who have got into North Korea without this palava (search for "The forbidden railway" if you want to know more), but the method they used is now forbidden to Westerners (they'll cancel your visa the moment you turn up in Pyong Yang if you've got the train in from Moscow), and is possibly punishable by imprisonment if they believe your motive was espionage.
Certainly if you do find a way in without a guide and start taking photos of planes, you're going to eventually hand your camera over to somebody in a uniform who doesn't like what he sees and you're going to cause a diplomatic incident. Given such incidents could lead to nuclear warheads being deployed (they're very twitchy, and in 1990 the Pentagon estimated if war broke out on the Korean peninsula there would be 1 million deaths in the first 24 hours), it's probably best if you don't do that. At all.
In short, if you're going to go plane spotting, make sure it's official, respectfully do as you're asked to by your guides, don't push the boundaries too far but challenge them lightly about their insistence you shouldn't interact with "uninteresting things" (they're the most interesting things), try and be be careful about what you say and do, and please, please, please write it up. It's rare and valuable social history.