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If you're big into crowd-sourcing:

There are super-inexpensive RTL-SDR dongles[1] that can be used to track airplanes such as this.

I'm not a lawyer, but I've fooled around with these dongles and a few programs enough to discern that Gov't aircraft absolutely need to broadcast their info on the 1090MHz band.

It wouldn't be much of a stretch to have a few people pop these up and see if they could monitor the airplanes that are monitoring the city! :)

Just to expand a little bit:

You get an SDR, plug it in and use a program like `dump1090` or FlightAware. The repurposed TV Tuner will then listen to data on 1090MHz and decode airplane's Active Dependent Surveillance-Broadcast (ADS-B) messages.

The ADS-B messages typically contain flight callsign, location (lat,lon), altitude, heading, and a few other tidbits.

There's a really active community around things like this. [2]

[1] http://www.amazon.com/RTL-SDR-DVB-T-Stick-RTL2832U-R820T/dp/... [2] http://www.rtl-sdr.com




Since, for whatever reason, I enjoy tracking flights as a hobby, here's a couple of extra tidbits:

1) If you are in the right area, Flight Radar 24 might actually give you the equipment for free. See here: http://www.flightradar24.com/free-ads-b-equipment for info.

2) It is unlikely that even aircraft that the government desires to be secret will stop broadcasting ADS-B anytime soon, as one of the major usages is avoiding mid-air collisions when airplanes are in airspace shared with commercial airliners. Secret surveillance planes might be unpopular, but they'll only be headline news if they were to run into a 757.

3) ADS-B broadcasts won't be required for all commercial airplane traffic[2] in the US until 2020. As such, there's still quite a few airplanes without it, particularly those that airlines plan to retire within the next five years.

[1] http://en.wikipedia.org/wiki/Automatic_dependent_surveillanc... [2] IIRC, the actual regulation is a requirement for ADS-B on all airplanes flying at 10K feet or above.


FlightAware has an awesome and rapidly growing ADS-B program as well. In particular, one of the easiest and cheapest ways to get into ADS-B flight tracking is with PiAware, which lets you convert a Raspberry Pi into an ADS-B receiver:

https://flightaware.com/adsb/piaware/

If you have a spare Android phone that you're not using anymore, you can even turn it into an ADS-B receiver:

https://flightaware.com/adsb/android/


I know absolutely nothing about this so forgive me if I'm asking a dumb question. ADS-B broadcasts so that other planes can figure out where you are and avoid you, correct? Why can't spy planes stop broadcasting it, but then listen for other planes' ADS-B signals, and just make sure to stay away from them? That way the only crash might be between two different spy planes?


It isn't mandatory. It'll be mandatory by 2020, but for now, these planes need to broadcast ADS-B.

http://en.wikipedia.org/wiki/Automatic_dependent_surveillanc...


There has been quite a few incidents in Europe concerning a certain neighbor of the EU doing this [1].

[1] http://www.google.com/search?q=transponder+russia


ADS-B isn't so much that it keeps 'your' plane from colliding with another one.

It's used to keep other planes away from you.

If there's an ADS-B broadcast for a specific location, then the autopilot on all other airplanes will automatically avoid that location.


genuine question, what do you get out of this hobby? i'm not trying to sneer or trivialize it, i'm sincerely curious about what makes it interesting to people who enjoy it


It's just an outgrowth of the fact that I find commercial aviation fascinating, really. I'll occasionally pull up flights near where I am, but I usually use tools to track whatever flights I find interesting for other reasons (off the top of my head, for instance, American Airlines' first revenue 787 flight was today, and I watched that one this morning).


Some people enjoy tracking birds some people enjoy tracking aircraft. If you're not into that you probably won't get it I knew a guy who was a plane spotter and he would get a kick of being able to recognize a commercial jet by its sound and even estimate it's approach and altitude. I didn't get why he enjoyed that, and i don't think that you can relate to that to understand it if you didn't decide to take up that hobby in the first place.


Personally, I find it really cool to just scan through the frequencies and see what's out there.

I've found pagers, police car radio, taxis, satellites, and airplanes.

It's pretty neat that a $10 usb stick can allow someone to listen in on such a variety of things.


You ever look up into the sky and see an airplane and wonder about it?

Here in the future, the answer's no further than your smartphone! Where it's going, where it's from, what it's carrying, freight or passenger? If you're near an airport, how busy is the airport? Which runway is that plane landing on? How many runways are there? What size airplane can that runway handle?

Just general curiosity, really.


Like similar hobbies, it's fun to play around with technical problem solving, numbers and data without the pressure of it being your real job. Often it's linked to a curiosity or experience from when you are young and you just find e tasks a relaxing escape from real world responsibilities. Also it's fun to belong to a community of people who enjoy technical talk.


I do this, and have checked my logs and found evidence of several surveillance aircraft. See my comment below with more details (https://news.ycombinator.com/item?id=9508812).



You miss the fact that ADS-B broadcasts are completely voluntary.

Basically, these were polite "black helicopters."

If they were up to something nefarious, you'd never know, no matter how sophisticated your ADS-B receiver is or what flightradar24 tells you.


1030 mhz will give you some more info in regards to what is being sent to the aircraft.


There is currently no requirement for airplanes to broadcast ADS-B signals.


I have two of those dongles (there were abouto $10 each) and living by the airport don't even need a particularly good antena do dump ADS-B messages out to the console.


Just on a whim, I stuck the little 6" whip antenna on the trunk of my car and plopped my laptop next to it, just to see what I'd get.

I was able to pick up flights taking off from DC, quite a good trip away. 100 miles?

Pretty awesome.




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