3mpire 0 #1 August 11, 2014 I read the following today: QuoteThe history of video review in skydiving goes back almost 30 years. An 8 way team by the name of Mirror Image was training down in Zephyrhills Florida and a guy by the name of Jim Baker was the camera flier. The camera equipment he wore was about the size of a regular sized video camera but he also had to wear a recording deck about as big as a full sized DVD player. His exit position was rear float, one time when he exited the DC-3 he was picked up by air traffic control radar in Tampa. Which got me to thinking... how big of a formation do you need to have before you might show up on ATC radar? Does modern radar technology filter out this kind of "noise" or does a sunset load 15 way RW jump show up on radar as a big meatball? Quote Share this post Link to post Share on other sites
Rover 11 #2 August 11, 2014 I believe 'Pieces of Eight' had a relatively strong radar signature at times.2 wrongs don't make a right - but 3 lefts do. Quote Share this post Link to post Share on other sites
3mpire 0 #3 August 11, 2014 Quote I believe 'Pieces of Eight' had a relatively strong radar signature at times. I'm assuming you mean the amputee skydiving team, not the 1978 concept album by styx Quote Share this post Link to post Share on other sites
JakGramley 2 #4 August 12, 2014 On one of the "Pieces of Eight" jumps about 12 years ago, the pilot was in contact with ATC on jump run. It was a single plane load, I believe out of a Skyvan. As soon as the formation left the plane, ATC immediately contacted the plane and demanded to know what have been released from the plane, because they were receiving a significant radar hit. They seemed sure that we had dropped a large metallic object from the plane. There were multiple chuckles at the Bombshelter that night over that. Jack Gramley Computer Consultant Quote Share this post Link to post Share on other sites
Trafficdiver 8 #5 August 12, 2014 I've been told that Boston Center can tell approx. many skydiver are in the air at Pepperell. It could be total BS but it is only about 5 miles away. Quote Share this post Link to post Share on other sites
Guru312 0 #6 August 12, 2014 3mpire I read the following today:... Which got me to thinking... how big of a formation do you need to have before you might show up on ATC radar? When I was flying jumpers in my Cessna 182 in the mid-70s ATC could routinely tell me when a single jumper left the plane. The ATC radar was a minimum of 12 miles away. I would guess that radar today is even more sensitive and a single jumper is discernible from a much greater distance.Guru312 I am not DB Cooper Quote Share this post Link to post Share on other sites
JohnMitchell 16 #7 August 12, 2014 I was an enroute controller, and we relied mostly on secondary radar, which reads encoded transponder signals from aircraft. Without an active transponder, you're invisible. Primary, or raw radar, reads the echoes off any reflective target. Reflectivity is a function of not just size, but shape, of the metal object ( Flesh, cloth, etc. tend to just absorb microwaves, I believe). The square sides of the old school video packs would make a good radar reflector, I'm sure. Ripcord housings and kicker plates, I don't know. Another thing is that enroute radar cancels out non-moving ( across the ground) targets, so skydivers would be considered ground clutter and deleted from most displays. I've worked a number of jump operations over the years and never really observed any skydivers on radar. Shorter range radar used by approach controls are more sensitive to primary (raw) radar returns. I have little experience with those. Any tower pukes out there have different experiences with this? Quote Share this post Link to post Share on other sites
3mpire 0 #8 August 12, 2014 That's interesting, John, thanks for the education. It makes sense when you think of radar for what it really is--microwaves. I knew that modern radar systems are processed before display, but wasn't sure how. It makes sense that non-moving ground clutter would be defined as things that don't have lateral speed. Though that makes me wonder if the squirrel suits with aluminized mylar on the arms might make a little blip do you know if the military uses the same type of system? NAS Whidbey might see more on a scope (especially when maggot's crew is jumping at jety city) if they have more sensitive settings. I have talked to one of the guys who flies for jet city and he said that NAS Whidbey ATC is very friendly to jumpers; if anyone can see something on scope maybe it's them Quote Share this post Link to post Share on other sites
topdocker 0 #9 August 12, 2014 My understanding is that the 100-way Canopy Formation World record showed up on radar. Of course it was the size of a building! topJump more, post less! Quote Share this post Link to post Share on other sites
billvon 2,991 #10 August 12, 2014 >My understanding is that the 100-way Canopy Formation World record showed up on radar. It would also have the advantage of having a considerable ground speed (depending on winds of course.) Quote Share this post Link to post Share on other sites
topdocker 0 #11 August 12, 2014 billvon >My understanding is that the 100-way Canopy Formation World record showed up on radar. It would also have the advantage of having a considerable ground speed (depending on winds of course.) I think at 13K they said we were doing 50 but slowed as we got lower. I think it was a 64 way then... Wonder what the radar image looked like!topJump more, post less! Quote Share this post Link to post Share on other sites
theonlyski 8 #12 August 12, 2014 I've received radar advisories for primary targets (no transponder) that ended up being a few birds. I have no doubt that a bunch of skydivers would get painted on the display. I've been meaning to get a tour of the Tampa ATC facility and if it ever materializes then I'll try to ask the guys if they see anything like that over zhills."I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly DPH -7, TDS 578, Muff 5153, SCR 14890 I'm an asshole, and I approve this message Quote Share this post Link to post Share on other sites
JohnMitchell 16 #13 August 13, 2014 3mpire do you know if the military uses the same type of system? NAS Whidbey might see more on a scope (especially when maggot's crew is jumping at jety city) if they have more sensitive settings. Yep, approach controls use primary radar much more than center (enroute) controllers, which I was. It's very possible jumpers could show up on radar. Someone mentioned birds showing up on radar. That's actually correct and I should amend my earlier statement about flesh and bone not reflecting radar. It's rare to see bird flocks but not unheard of. Most of my time was spent ignoring primary radar unless a particular blip starting leaving histories like an airplane. Called a couple of those that were a big surprise to the pilots. Quote Share this post Link to post Share on other sites
Hellis 0 #14 August 13, 2014 JohnMitchell I was an enroute controller, and we relied mostly on secondary radar, which reads encoded transponder signals from aircraft. Without an active transponder, you're invisible. Primary, or raw radar, reads the echoes off any reflective target. Reflectivity is a function of not just size, but shape, of the metal object ( Flesh, cloth, etc. tend to just absorb microwaves, I believe). The square sides of the old school video packs would make a good radar reflector, I'm sure. Ripcord housings and kicker plates, I don't know. Another thing is that enroute radar cancels out non-moving ( across the ground) targets, so skydivers would be considered ground clutter and deleted from most displays. I've worked a number of jump operations over the years and never really observed any skydivers on radar. Shorter range radar used by approach controls are more sensitive to primary (raw) radar returns. I have little experience with those. Any tower pukes out there have different experiences with this? So what you are saying is that you *could* build a formation that spelled something to the ATC guys, or make a drawing? Like a drawing/formation of the middle finger extended to show what we really think of beeing put on hold up there. Quote Share this post Link to post Share on other sites
JohnMitchell 16 #15 August 13, 2014 Hellis So what you are saying is that you *could* build a formation that spelled something to the ATC guys, or make a drawing? Like a drawing/formation of the middle finger extended to show what we really think of beeing put on hold up there. Well, wearing a bunch of aluminum foil under the jumpsuits would help. And I've never seen that high of resolution in civilian radar to read something spelled out. What the military has, I don't know. In our country, not many DZ's are in airspace that requires permission to jump. Most just give a one minute warning and the controller issues traffic advisories. The controller may advise not to drop, but can't force the pilot not to. Are the rules more rigid in Sweden? Quote Share this post Link to post Share on other sites
Hellis 0 #16 August 13, 2014 JohnMitchell *** So what you are saying is that you *could* build a formation that spelled something to the ATC guys, or make a drawing? Like a drawing/formation of the middle finger extended to show what we really think of beeing put on hold up there. Well, wearing a bunch of aluminum foil under the jumpsuits would help. And I've never seen that high of resolution in civilian radar to read something spelled out. What the military has, I don't know. In our country, not many DZ's are in airspace that requires permission to jump. Most just give a one minute warning and the controller issues traffic advisories. The controller may advise not to drop, but can't force the pilot not to. Are the rules more rigid in Sweden? Usually a 1 or 2 minute call is enough, but or DZ is in perfect line with a international airport about 30 km away. All flights landing or starting, depending on wind, will fly above the DZ. Quote Share this post Link to post Share on other sites
JohnMitchell 16 #17 August 13, 2014 Hellis Usually a 1 or 2 minute call is enough, but or DZ is in perfect line with a international airport about 30 km away. All flights landing or starting, depending on wind, will fly above the DZ. We have a similar situation of a major airport's departure route passing above our DZ. Luckily "above" is the key word here. Only seems to be a factor doing high altitude (18K feet or more) jumps. Quote Share this post Link to post Share on other sites
nigel99 475 #18 August 15, 2014 JohnMitchell *** do you know if the military uses the same type of system? NAS Whidbey might see more on a scope (especially when maggot's crew is jumping at jety city) if they have more sensitive settings. Yep, approach controls use primary radar much more than center (enroute) controllers, which I was. It's very possible jumpers could show up on radar. Someone mentioned birds showing up on radar. That's actually correct and I should amend my earlier statement about flesh and bone not reflecting radar. It's rare to see bird flocks but not unheard of. Most of my time was spent ignoring primary radar unless a particular blip starting leaving histories like an airplane. Called a couple of those that were a big surprise to the pilots. Flesh and bone doesn't absorb microwaves very efficiently and it will depend on the frequency used as well. It would be very interesting to see how it showed up.Experienced jumper - someone who has made mistakes more often than I have and lived. Quote Share this post Link to post Share on other sites
JohnMitchell 16 #19 August 15, 2014 nigel99 Flesh and bone doesn't absorb microwaves very efficiently and it will depend on the frequency used as well. It would be very interesting to see how it showed up. Yep, in fact it's the water that heats in a microwave oven, not dry stuff. Of course, absorbing microwaves or letting them pass thru doesn't make one show up on radar. It's all about the reflection. Quote Share this post Link to post Share on other sites
iowa 0 #20 August 15, 2014 The demo team I used to jump with would jump into Rockford, IL on labor day weekend two jumps a day. The campground we stayed at (let us stay free if we jumped in each day) was less than mile from the ATC and they said they could see our three stack every time. Keith ''Always do sober what you said you would do drunk. That will teach you to keep your mouth shut.'' - Ernest Hemingway Quote Share this post Link to post Share on other sites
JohnMitchell 16 #21 August 16, 2014 iowa was less than mile from the ATC and they said they could see our three stack every time. That's close enough to cook a hot dog in your pocket. Quote Share this post Link to post Share on other sites
airdvr 210 #22 August 22, 2014 JohnMitchell , ...so skydivers would be considered ground clutter... I've known a lot of skydivers that i considered to be ground clutter. Please don't dent the planet. Destinations by Roxanne Quote Share this post Link to post Share on other sites
JohnMitchell 16 #23 August 22, 2014 airdvr ***, ...so skydivers would be considered ground clutter... I've known a lot of skydivers that i considered to be ground clutter. Quote Share this post Link to post Share on other sites
