How i see what aircraft are in the immediate area for star pointing.

So alongside with lasers and general electronics, ive been getting into another hobby, SDR. Basically SDR, for those who dont know, is software defined radio that allows you to tune into any frequency within range of the tuner. In my case i use a RTL-SDR. Anyways, i just got done looking over a thread that mentioned that someone got caught and arrested for being very stupid/ignorant and pointed at a police helicopter. Then i saw someone mention that police helicopters and other governmental aircraft may turn their lights out and will be able to travel pretty quietly. So with SDR we can see those aircraft traveling over us or within a rough 50 mile radius depending on the antenna. All aircraft are required by 2020 to have this beacon on board. So we can use this to determine if there are any aircraft that are about to cross our area or are in our area. If we can see the live map of aircraft we received, we can be a lot more careful about shining lasers in the sky to witness that amazing beam or to point at stars :beer:

Any thoughts? More info can be found on youtube if anyone is interested. Just search "aircraft SDR"

Thanks for reading!

kuhny1 said:

So alongside with lasers and general electronics, ive been getting into another hobby, SDR. Basically SDR, for those who dont know, is software defined radio that allows you to tune into any frequency within range of the tuner. In my case i use a RTL-SDR. Anyways, i just got done looking over a thread that mentioned that someone got caught and arrested for being very stupid/ignorant and pointed at a police helicopter. Then i saw someone mention that police helicopters and other governmental aircraft may turn their lights out and will be able to travel pretty quietly. So with SDR we can see those aircraft traveling over us or within a rough 50 mile radius depending on the antenna. All aircraft are required by 2020 to have this beacon on board. So we can use this to determine if there are any aircraft that are about to cross our area or are in our area. If we can see the live map of aircraft we received, we can be a lot more careful about shining lasers in the sky to witness that amazing beam or to point at stars :beer:

Any thoughts? More info can be found on youtube if anyone is interested. Just search "aircraft SDR"

Thanks for reading!

Click to expand...

I'm assuming you're using the SDR to receive ADS-B?

Not all aircraft are equipped with ADS-B transmitters, and not all aircraft will be by 2020 either. Certainly much of the air traffic here in Yellowknife doesn't have it, only the larger 737s and such use it. Worked for a couple of aviation companies here, I know their aircraft aren't equipped with it (at least, most of the fleet definitely isn't) and I know the competition wasn't either ... Although they're still flying aircraft that flew in WW2 so that's hardly surprising.

ADS–B equipment is currently mandatory in portions of Australian airspace, the United States requires some aircraft to be equipped by 2020[5] and the equipment will be mandatory for some aircraft in Europe from 2017.[6][7] Canada is currently using ADS-B for rather limited air traffic control, mainly in the Hudson Bay area.

Click to expand...

Don't rely on it, use your eyes and ears and be careful if you're pointing outside.


SDR sure is fun though!

I agree, I'd trust my eyes, helicopters flying with their lights out at night are breaking FAA rules, I don't know how they can get away with doing that.

I mentioned it already several times here. I use FlightRadar app as an assistance. But as mentioned above eyes and ears need to be used primairly.

Yeah, I would never use this to assume nothing is overhead, just more of a extra precaution, more as a heads up that there might be something on it's way that I can't see or hear. However I was not aware that it's only required in certain areas.

In my experience when doing outdoor laser painting, where longer exposure is needed, I just look for larger area in the app to estimate planes coming into my place. If you use this app for some time you can get used to corridors and it is much easier. Also you will be surprised how large area it is for a 10-15 minutes of jet airliner air speed. Considering a circle you get diameter of 20 to 30 minutes of flight time - lets say its 800 km/h ground speed - so 400 km diameter circle to look to be safe as minimum. However some planes are not showed there and some areas like near to military bases small airports etc. it cannot help much. But still it helps a lot in most cases. When I see something will come in lets say in 10-15 minutes (considered time of exposure) I prepare my stuff and wait till it passes before switching lasers on. It might seem in majority of real situations I'm taking it too seriously and wasting time instead of doing more pics, but it is just lowering potential risk to acceptable minimum by learning this habbit. Good to have and keep respect with lasers. Even if the beam is not in the direction of aircraft it is better to keep it off as some suden surprise of wild life for exame might distract me and I could just forget about laser on...

Look and listen, I mean really sit and listen, you can hear a lot that's flying at a long distance, I have seen satellites go by, you can see the moons reflection off one side at times and they go by straight and very high, I have seen drones too in the daytime, wear your amber glasses, it helps you see then in the daylight.
I would avoid the star pointing unless it's very clear and ZERO aircraft.

If you wish to point the star even if you are sure it is a star, do not point on it, circle around it instead. More safe... Also better to use low powers, even 5 mW 532 nm might be sufficient for small groups and most of night light conditions. 50 mW 532 nm I would consider as maximum even for large groups of people. Just my opinion.

If you just wanna point out stars to people in city light conditions you'll generally want something like a 30-50mw 532nm. That will function well at pointing out the stars while maintaining a minimally visible beam from the sides. 5mw isn't really bright enough in areas with light pollution.

Yes, with high light pollution - like city conditions - 5 mW will not be very visible, but majority of stars too. For like 2-3 people 5 mW greenie works pretty well in my area (larger city is about 10 - 15 km far) but not during sunset and some time after. That's what I meaned - to clarify my previous post.

I still think that if you are taking beam shots at dusk or night it is statistically improbable that you will hit an aircraft that is flying 4 to 5 miles high. I live at least 25 miles from SeaTac airport and all the planes I see are very tiny lights in the sky. The only low flying aircraft we get are military and you can hear them coming long before they get to you. I believe that almost, if not all, laser attacks on aircraft are intentional. But, that doesn't mean that I don't look and listen for something flying if I am going to be shining a laser skyward.

Yes, I think the same. However I've read somewhere (probably LP safety) something like this - "if you do not know divergence and beam diameter at aperture, assume 1 mrad and one mm" - was used for some hazard distance calculations. It is the same case here: You know it is unlikely in reality, but you assume the worst case scenario, to get one sided estimate of all possible scenarios. "Just" safety measure.

What about lasing into low thick clouds. Say a 1w 532nm. Is the cloud cover going to dampen the beam enough to not be noticeable to aircraft above it? I get a sense of safety from the cloud cover but it could be a dangerous false assumption.

dden4012 said:

What about lasing into low thick clouds. Say a 1w 532nm. Is the cloud cover going to dampen the beam enough to not be noticeable to aircraft above it? I get a sense of safety from the cloud cover but it could be a dangerous false assumption.

Click to expand...

The passengers and pilots on the plane might notice a green 'spotlight' effect coming up through the clouds, but I cannot imagine it being harmful under any circumstance.

Ditto on that and I have a couple thousand hours as a private pilot, haven't seen it, but all it would do is light up a cloud with a green color. Maybe if you shot through a hole but I doubt you would be unlucky enough to hit them in the eye, even if you did, they wouldn't see where the beam originated from, although not what you are concerned about.

Yeah that was another thing I was wondering too. You would think the beam would be way out of focus miles away. Unless you have some lens that isnt available to the public... Honestly though if I were a passenger on a jet, and saw a cloud glowing green I would be pretty amazed.