Can radar detect skydivers?

Interesting discussion, thanks for the info. So it seems that if someone on radar is really looking they may be able to pick up a single skydiver if they're lucky. And this is usually ATC who knows that there is skydiving going on.

How about in our hypothetical situation of a plane coming over the border? Who is watching that? The Border Patrol? It could fly over in a spot well out of concern of any airports and probably get away with it. Which means my buddy wins and I'm buying beer lol...

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It doesn't matter that air is transparent to radar. Radar produces electromagnetic fluctuations in the 'radio wave' frequency. For radar to work signals are reflected.

But does nylon reflect radio waves? Is this reflection enough to be received back?

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I'm not sure all that nylon would show up very well on the RADAR.

It has something to do with the dense air trapped in the cells. And it takes a certain amount of it. Conversations with our pilots and the local ATC seem to indicate that you need a 260+ sf canopy to generate a return.

I'm calling Bullshit on that one!.

The dense air comes from someone on here saying that that's how wx radar sees stuff.

I do know that the ATC guys can't see us in freefall but as soon as a large canopy opens, they know it. Now for students, I'd give you the metal in the spring-loaded PC. But my 269 sf shows up just fine and due to my set up, I have less metal exposed upon deployment than the smaller canopies that the radar can not see at all..

-Blind

Yes, I was joking :-)

Back in the 80's at Perris ATC did ask why the Crew formations were opeing so high.

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properly calibrated radar can detect the differences between specular and non-specular returns from nearly any 'reflective' surface. Its mostly a matter of having enough resolution avail in the area while the formation is exposed at optimal angles.

most skydiving activities would generally fall in the realm of clutter, but could still be observed.

I understand specular and non-specular, but it still boils down to the reflectivity of nylon in the GHz regime. I still reject the air pressure issue.

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The dense air comes from someone on here saying that that's how wx radar sees stuff.

Weather radar sees precipitation, period, not clouds or turbulence or dense air. At least that's what I've been taught the last 22 years by the FAA. Some doppler radar used for windshear detection uses reflections from wind borne dust and insects to measure wind velocity. If radar could see air, it would simplify that and a few other tasks. And I still doubt that nylon reflects radar waves efficiently, regardless of the shape.

I was told even a bigger flock of birds are visible on primary radar. Why are you so surprised if it could happen with skydivers?

Huntsville ATC, located about 40 miles from our DZ at Skydive Alabama, picks up our canopies easily they say. big or small...

in reply to "Me and another guy think that not only would they know a plane entered illegally, they would also be able to tell that someone or something jumped/fell out of it and track his progress to the ground. But then again the Special Forces use this type of method to get behind ememy lines without detection so maybe he could get away with it. Maybe he wouldn't show up until the chute opened and there was a bigger profile? "
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Seems like the correct answer here could be a national security issue.

After reading this thread it seems likely that radar can more effectively detect a skydiver and their canpoy if they are covered in dust and insects just like for air -pressurised or not.
A very clean bug free skydiver may be radar invisible.??

It's my guess that todays radar could be callibrated to count the coins in your pocket ....if so required......maybe.

I got my altimeter painted with radarabsorbing paint!

No serious.

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And I still doubt that nylon reflects radar waves efficiently, regardless of the shape.

efficiently? no. Detectibly? yes.

there are documented cases of (airborne) radar picking up leaves from trees...

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After reading this thread it seems likely that radar can more effectively detect a skydiver and their canpoy if they are covered in dust and insects just like for air -pressurised or not.
A very clean bug free skydiver may be radar invisible.??

It's my guess that todays radar could be callibrated to count the coins in your pocket ....if so required......maybe.

a wet skydiver/canopy would be more reflective and larger surfaces with hard angles are more reflective as well... dust and insects would be largely insignificant ON a skydiver.. but they do allow the airflow to be 'illuminated' under the right conditions...

I used X and S band marine radars on commercial fishing boats. On X band we could pick up pelicans on radar about as far as you could see them. On S band sets we could pick birds up many miles away. You would think that a pelican is the ideal stealth aircraft, but nope. Furuno markets certain radars as "Bird Radars" to tuna boats which use birds to locate fish schools. I bet a skydiver with gear is at least as good a microwave reflector as a bird. Some ground radars looking at aircraft have doppler velocity filters to screen out anything that isnt moving at a certain minimum horizontal velocity. It cuts down on extraneous echos.

Some of the BULLSHIT replies in this thread crack me up. While I haven't LOOKED for actual skydivers I know RADAR can see flocks of birds and such so anything that is "reflecting" a return can be viewed on my screens. With that said, no I am not going to see a 280 Sq. ft. parachute. I may see a healthy sized CRW formation however. I haven't tried to look at a big way in free fall from my RADAR screen but I would have to say they would create some sort of clutter if there were enough of them.

don't sound like anyone is 100%. we need to put a proposal together to look into this. of course involving many "research jumps" Some military branch will like to fund that.

280 sq ft is PLENTY big enough for 'me' to see....

but my radar has a completely different mission than yours does. "Clutter" is a relative term

Does it really matter if radar can see the jumper? First off, who is watching? I doubt ATC is going to track the jumper to the ground. Absent military radar watching the border I doubt anyone would notice.

But let's say someone does notice. Now what? Is there a procedure for ATC, military or anyone else to notify the Border Patrol or anyone else?

A friend of mine who works for the border patrol has a patrol area the size of Rhode Island. Let's say his sector was notified and they told him. If the jumper planned this carefully and had someone waiting to pick him up, then the jumper is long gone before anyone can respond. If it’s a HAHO jump, then the jumper could exit over Mexico and land 25 or more miles into the desert.

All that said, wouldn’t it be easier to get in other ways? This seems like lot's more effort then is warranted for someone to sneak over to pick lettuce. So let's say a spy or a terrorist wants to get in. Wouldn’t it be easier to come in on a pleasure boat, or to drive in from Canada? Jumping will get a single person in but not with any substantial equipment.

It seems to me that if our boarders are so secure that this is what’s needed to penetrate them, then the border patrol, customs and military must be doing one heck of a job! I hope we actually get to this point.

Metal isn’t needed to reflect radar signals, I saw birds nearly every day on X band marine radar when I was skippering commercial fishing boats.
 

Radar signals are reflected by any object having a density difference from air. Furuno makes specialized S band bird radars that can image a single seabird many miles away. 

 

I got it first hand from an FAA controller who also skydives that exiting skydivers can be seen on radar. He has seen them many times. 

Edited May 6, 2021 by 377

On 5/6/2021 at 2:38 PM, 377 said:

Metal isn’t needed to reflect radar signals, I saw birds nearly every day on X band marine radar when I was skippering commercial fishing boats.
 

Radar signals are reflected by any object having a density difference from air. Furuno makes specialized S band bird radars that can image a single seabird many miles away. 

 

I got it first hand from an FAA controller who also skydives that exiting skydivers can be seen on radar. He has seen them many times. 

Especially Wing Suiters. I have a friend who knows a guy and he told me.......

a jal 747 came awful close on Saipan back in 2000 , some body did not see us