"Radar equipped"

RotorDude said:
I typically see about 2-5 minutes delay, which is perhaps a mile or two, tops. But what's very important is that you don't see a static picture, but a dynamic one: your weather dynamically loops on the display so you have a good idea of how the cells are moving and evolving. Which means you can easily interpolate their location (and strength), not only to current time, but to future time, e.g. when you'll get to the area of a given cell. Then you need to plan how to deal with it, generally giving its leading edge a wider berth.
Click to expand...
This is why ADS-B is great for avoiding the bad areas. But it won't necessarily show you when a cell develops which is a good reason to be wary about using it to navigate through the nasty stuff.

Someone earlier mentioned using ADS-B to fly through green and yellow and avoiding red. That's nuts to me. Green, fine, but I would never intentionally fly through yellow.
 
Fearless Tower said:
This is why ADS-B is great for avoiding the bad areas. But it won't necessarily show you when a cell develops which is a good reason to be wary about using it to navigate through the nasty stuff.

Someone earlier mentioned using ADS-B to fly through green and yellow and avoiding red. That's nuts to me. Green, fine, but I would never intentionally fly through yellow.
Click to expand...

When combined with Stormscope, I have never had an issue flying through ADS-B yellow. Even the odd orange has not been a problem (just heavy rain at most but no major turbulence), when the Stormscope is clear. OTOH, when the Stromscope says "beware", I do. (But bear in mind the caveats about getting signal out of the noise in the Stormscope which I mentioned above).
 
Fearless Tower said:
You must have had a really good stormscope. The one I had in the Baron gave way too many false alerts to be reliable.
Click to expand...

I find the WX500 hooked up to the garmin box to be very accurate and fairly immune to spurious detection. The older (WX10 ?) wasn't that useful in my hands.
 
weilke said:
I find the WX500 hooked up to the garmin box to be very accurate and fairly immune to spurious detection. The older (WX10 ?) wasn't that useful in my hands.
Click to expand...
I think I might have that in the Twin Beech, and I haven't seen many false hits, although I don't get anywhere near as close to bad stuff as I did in the Baron.
 
RotorDude said:
I typically see about 2-5 minutes delay, which is perhaps a mile or two, tops. But what's very important is that you don't see a static picture, but a dynamic one: your weather dynamically loops on the display so you have a good idea of how the cells are moving and evolving. Which means you can easily interpolate their location (and strength), not only to current time, but to future time, e.g. when you'll get to the area of a given cell. Then you need to plan how to deal with it, generally giving its leading edge a wider berth.
Click to expand...

That works as long as you have defined 'storms' that move in a given direction. Where I find it near useless is the setting of humid unstable air in the southeast with storms just 'popping' everywhere around you without much of a forward movement.
 
How do you know it is only a 2-5 minute delay from when the data was taken not just when it was transmitted to your receiver? Most of what I have read has put the normal delay at 15 minutes. Unless there is a timestamp of when the data was taken, think metar report, you have no way of knowing how old that weather really is.

From the Garmin 345 Pilots Guide

" WARNING
Do not use the indicated data link weather product age to determine the age of
the weather information shown by the data link weather product. Due to time
delays inherent in gathering and processing weather data for data link
transmission, the weather information shown by the data link weather product
may be significantly older than the indicated weather product age."


We have been flying for 10 years with XM weather in our airplanes. I remember crossing Arizona 2-3 years ago and seeing a lone cell rapidly building a good ways in front of us north of our route. At that time the XM showed a small green area but our onboard weather radar was painting a totally different picture. We were at FL410 and when we got close we estimated the top of this cell at 35,000 to 37,000 feet. By this time the XM was starting to show a little yellow while our radar show a nice sized red area with a little magenta.

Not trying to criticize just trying to point out to some on this thread that there is a delay and in rapidly changing weather it can make a big difference. As shown in the video that iamtheari posted.

One of our airplanes is in the shop having ADS-B in/out installed and I look forward to see how it compares to the XM which I really like.
 
This past summer, I was flying with a young copilot. As we approached some weather, he was glued to his iPad. He suggested we deviate to the right. I told him not yet. The closer we got, the more he squirmed, still adamant that we needed to turn right. Finally, when he started looking at me like I'm a suicidal maniac, I said "look out the window! I'm looking at blue sky and sun right through the hole in front of us. A right turn would put us right into the cell you are trying to avoid."
 
Plano Pilot said:
One of our airplanes is in the shop having ADS-B in/out installed and I look forward to see how it compares to the XM which I really like.
Click to expand...
The delays will be the same. The suite of weather products is a bit different and, since ADS-B weather is line of sight ground-based, you ADS-B ability to pick up weather on the ground is quite limited.

Whether any of that makes a difference to you (i.e., is worth the XM subscription charge) is a strictly personal preference.
 
Haha, yup. I was flying right seat in a Cheyenne one day and we had pop ups all over the place. Left seater (my old CFI) was glued to the radar and told me to tell ATC he wanted a turn. I said we're good on this heading, he says I want a turn. Finally I said "look outside", he looks up and sees our present heading clears two cells miles apart, right between them, and says, "oh". Of course I gave him some shet about it but we were buds too.
 
Best advice from the check airman I got on IOE was the best radar is your eyes. Of course that only works when you can actually see the build ups but it's very true.
 
Plano Pilot said:
How do you know it is only a 2-5 minute delay from when the data was taken not just when it was transmitted to your receiver? Most of what I have read has put the normal delay at 15 minutes. Unless there is a timestamp of when the data was taken, think metar report, you have no way of knowing how old that weather really is.
Click to expand...
I think the 'normal delay of 15 min' is more of a disclaimer. That used to be fairly typical, but I have noticed an improvement in the updates in recent years.

Perhaps someone else can confirm, but I believe the time stamp on ADS-B is when the data was taken. When the updates show up in ForeFlight, they are typically at least a couple minutes old, sometimes more.

Either way, the net effect is the same. Whether it is 2-5 min time late or 15, you shouldn't be using ADS-B to penetrate cells, at least unless you can physically see them.

ADS-B is best used to avoid the bad stuff.
 
I have not tracked any time stamps but based on my visual and ADS-B comparisons I'd say the delay is typically 5-10 minutes but infrequently it might be a bit more than that. For my flying that is inconsequential. If you can't see the weather inside my rule would be a 15+ min. flight margin.
 
weilke said:
That works as long as you have defined 'storms' that move in a given direction. Where I find it near useless is the setting of humid unstable air in the southeast with storms just 'popping' everywhere around you without much of a forward movement.
Click to expand...

Even if there is no defined movement, there would still be an evolution. A storm doesn't pop up in seconds, it takes at least 15 minutes (as a rough guess) for the fastest storm cell to grow from absolutely nothing into a serious menace. During that time you should be seeing several hits on the ADS-B that allow you to extrapolate into the near future and decide on avoidance strategies. Also, if you have Stormscope (which I personally consider an essential complement to ADS-B), it will pick up even the "invisible" lightning strokes, which seem to occur well before the storm is mature (and sometimes it might never become fully mature), and if you avoid those dots you'll assure yourself a smooth ride. Of course ideally you want both modes, and by combining them into a composite picture (in your head or on the screen), your extrapolation and decision making should be pretty reliable, in my experience. And as I noted above, ATC is there to help you, so if unsure you can certainly use them for sanity checking.
 
RotorDude said:
Even if there is no defined movement, there would still be an evolution. A storm doesn't pop up in seconds, it takes at least 15 minutes (as a rough guess) for the fastest storm cell to grow from absolutely nothing into a serious menace. During that time you should be seeing several hits on the ADS-B that allow you to extrapolate into the near future and decide on avoidance strategies.
Click to expand...

15min can be as little as one update. If the counter on the XM says 1min the data is already 7min old. If the. Counter is at 8min you are looking at 14min old composite data.
 
jordane93 said:
Best advice from the check airman I got on IOE was the best radar is your eyes. Of course that only works when you can actually see the build ups but it's very true.
Click to expand...

That's absolutely right. My own experience is that nothing beats your eyes. Yes, sometimes the soup is dense and you see nothing outside, but in a convective environment it's rare not to have at least sporadic "peeks" and typically more. And if you use those visual cues properly for extra intelligence on what's cooking, coupled with all your electronic gizmos, you'd be much better off as far as both ride quality and safety.
 
weilke said:
15min can be as little as one update. If the counter on the XM says 1min the data is already 7min old. If the. Counter is at 8min you are looking at 14min old composite data.
Click to expand...

I would be very wary of flying without Stromscope in a convective environment. And the Stromscope will give you instantaneous updates on the storm cell's development, so 15 minutes is a long time. But even ADS-B normally gives you a lot more updates than once per 8 minutes, I would say one per 2 minutes is what I see typically, so about 7 readings to extrapolate from in this hypothetical situation. But again, I would not recommend trying to rely on ADS-B alone for avoidance. If my Stormscope were down, I'd rely more on ATC, and be a lot more conservative in general.
Also, can't speak to XM Weather, but ADS-B gives me typical 2-5 minute latency, based on my experience over the last few years (comparing the depicted cell vs. where it really is).
 
Last edited:
RotorDude said:
And the Stromscope will give you instantaneous updates on the storm cell's development, so 15 minutes is a long time. But even ADS-B normally gives you a lot more updates than once per 8 minutes, I would say one per 2 minutes is what I see typically, so about 7 readings to extrapolate from in this hypothetical situation.
Click to expand...

The NWS radar that ADSB is based on creates one
Image every 6 minutes.
 
Plano Pilot said:
How do you know it is only a 2-5 minute delay from when the data was taken not just when it was transmitted to your receiver? Most of what I have read has put the normal delay at 15 minutes. Unless there is a timestamp of when the data was taken, think metar report, you have no way of knowing how old that weather really is.

From the Garmin 345 Pilots Guide

" WARNING
Do not use the indicated data link weather product age to determine the age of
the weather information shown by the data link weather product. Due to time
delays inherent in gathering and processing weather data for data link
transmission, the weather information shown by the data link weather product
may be significantly older than the indicated weather product age."


We have been flying for 10 years with XM weather in our airplanes. I remember crossing Arizona 2-3 years ago and seeing a lone cell rapidly building a good ways in front of us north of our route. At that time the XM showed a small green area but our onboard weather radar was painting a totally different picture. We were at FL410 and when we got close we estimated the top of this cell at 35,000 to 37,000 feet. By this time the XM was starting to show a little yellow while our radar show a nice sized red area with a little magenta.

Not trying to criticize just trying to point out to some on this thread that there is a delay and in rapidly changing weather it can make a big difference. As shown in the video that iamtheari posted.

One of our airplanes is in the shop having ADS-B in/out installed and I look forward to see how it compares to the XM which I really like.
Click to expand...

That,

XM is great when youre in the flight levels and are trending the weather hundreds of miles ahead, big picture stuff, but for the closer "tactical" stuff, that's onboard radar or VMC eyeballs, otherwise hang on to your hats
 
weilke said:
The NWS radar that ADSB is based on creates one
Image every 6 minutes.
Click to expand...

In that case, why/how do they produce a report every 2.5 minutes?
(see "Service Transmission" in table)
And leaving numbers and tables aside, how come I see (what appears to be) a fresh report every couple of minutes?
 
Last edited:
My rather short but intensive experience with ADS-B makes me believe that it is almost as good as radar. As far as the "big picture" goes it provides individual cell images and these are right where I expect them to be when comparing them to a look-see out the window. So far I haven't come across a single experience where ADS-B differed from what was expected or from actual conditions. There is a setting in Foreflight that you may need to watch out for that shows "composite" vs. "Lowest Tilt" that presents very different images of actual conditions. However, I believe ADS-B weather (along with traffic) might be one of the greatest safety advances for general aviation flying that we've seen since the seat belt. I'd be interested in hearing from others that have had a different experience.
 
Last edited:
flyzone said:
My rather short but intensive experience with ADS-B makes me believe that it is almost as good as radar. As far as the "big picture" goes it provides individual cell images and these are right where I expect them to be when comparing them to a look-see out the window. So far I haven't come across a single experience where ADS-B differed from what was expected or from actual conditions. There is a setting in Foreflight that you may need to watch out for that shows "composite" vs. "Lowest Tilt" that presents very different images of actual conditions. However, I believe ADS-B weather (along with traffic) might be one of the greatest safety advances for general aviation flying that we've seen since the seat belt. I'd be interested in hearing from others that have had a different experience.
Click to expand...
Nonetheless, it is delayed "radar." Great tool for long range avoidance but often not good for close in avoidance, Having said that when conditions are relatively static, it can work sort of like real WX radar.
 
If it has a 15 minute delay and the storm is moving 20mph, then the cell could be 5 miles off. Like the guy said, you have to have the progression of movement, history, whatever its called so you can see where the cell is headed.

Onboard radar is better for penetrating fronts, Nexrad is best at long range planning.
 
RotorDude said:
In that case, why/how do they produce a report every 2.5 minutes?
(see "Service Transmission" in table)
And leaving numbers and tables aside, how come I see (what appears to be) a fresh report every couple of minutes?
Click to expand...
The table you're looking at appears to state how often the radar data is transmitted over ADS-B. That ensures that a plane coming into range of the transmitter will not have to wait more than 2-1/2 minutes to get radar data or more than 10 minutes for PIREPs and so on, but it says nothing about the age of the data itself. And maybe the report looks like it's fresh each time, but it could just be that each report is 10 minutes out of date and you're getting fresh but still 10-minute-old reports. I haven't spent enough time in contact with an ADS-B tower and enough ADS-B-out-equipped planes to have a feel for the age of the weather data I would get, so I defer to those with actual knowledge or experience on the actual numbers. But I am going to remain cautious about using ADS-B radar data for anything but giving a very wide berth to bad weather.

And no matter what, I'm not going to say I am "radar equipped" unless I have an actual realtime radar system on the plane.
 
iamtheari said:
The table you're looking at appears to state how often the radar data is transmitted over ADS-B. That ensures that a plane coming into range of the transmitter will not have to wait more than 2-1/2 minutes to get radar data or more than 10 minutes for PIREPs and so on, but it says nothing about the age of the data itself. And maybe the report looks like it's fresh each time, but it could just be that each report is 10 minutes out of date and you're getting fresh but still 10-minute-old reports. I haven't spent enough time in contact with an ADS-B tower and enough ADS-B-out-equipped planes to have a feel for the age of the weather data I would get, so I defer to those with actual knowledge or experience on the actual numbers. But I am going to remain cautious about using ADS-B radar data for anything but giving a very wide berth to bad weather.

And no matter what, I'm not going to say I am "radar equipped" unless I have an actual realtime radar system on the plane.
Click to expand...

Regarding the frequency of ADS-B refreshes, if what you are assuming were correct, that the number in the table is the broadcast rate, regardless of data freshness, that wouldn't make sense, for at least two reasons. First, if what you say were true, then the "looping" mode would show "frozen" pictures between temporal data points, i.e. it would not show a new frame every 2 minutes or so while looping (which it clearly does, along with the frame's age). Second, in my experience to date, I have not seen any noticeable lag between the displayed ADS-B location of a cell vs. the Stormscope or eyeball inputs.
Regarding the reply to ATC question raised by the OP, I consider telling ATC you are "radar equipped" when you don't have on board radar installed to be lying, so I would never recommend that.
However, in my own experience under similar circumstances, ATC typically asks "do you have some kind of weather equipment on board?", which makes more sense, since they are fully aware of ADS-B as an option, and of course Stormscope, which has been around for ages. If they did ask specifically about radar, I'd reply, "Negative, but we have Stormscope and ADS-B."
 
RotorDude said:
Regarding the frequency of ADS-B refreshes, if what you are assuming were correct, that the number in the table is the broadcast rate, regardless of data freshness, that wouldn't make sense, for at least two reasons. First, if what you say were true, then the "looping" mode would show "frozen" pictures between temporal data points, i.e. it would not show a new frame every 2 minutes or so while looping (which it clearly does, along with the frame's age). Second, in my experience to date, I have not seen any noticeable lag between the displayed ADS-B location of a cell vs. the Stormscope or eyeball inputs.
Click to expand...
Like I said, I defer to your experience. But I wouldn't assume that the data being sent on each 2.5-minute update is a single frame of radar imagery. It could be the entire loop for the past hour for all I know. I haven't studied it enough to know what exactly is sent during the transmission of radar data that occurs on that interval.
 
iamtheari said:
Like I said, I defer to your experience. But I wouldn't assume that the data being sent on each 2.5-minute update is a single frame of radar imagery. It could be the entire loop for the past hour for all I know. I haven't studied it enough to know what exactly is sent during the transmission of radar data that occurs on that interval.
Click to expand...

Interesting point. I have yet to find a definitive reference on that issue. Until now I have assumed that only a single frame is sent at a time, and it is your local device that prepares the "looping" display by caching the older frames, and I can almost swear that when I turn it on in flight I initially see only a single frame which gradually builds up into a loop, but am not absolutely sure. I do agree that regardless of specs, it's the bottom line that counts as far as "freshness", which is why I (in general) never completely trust any single input, and always compare them to each other. In this case, I can't recall the FIS-B Nexrad display being different enough from the other inputs (Stormscope, visual, ATC) to be noticeable (over approx. 3 years of flying). But again, I treat any single input with suspicion - "Доверяй, но проверяй".
 
You've increased my Russian vocabulary by two words, so either way I count this as among the most productive online discussions I've ever been part of. I have no reason to assume that it doesn't work as you suggested, one frame per 2.5-minute update. I just know how software engineering works and, unless I see a spec document and a quality assurance report that says the product works according to that spec after extensive testing, I don't want to make any assumptions at all about what data is coming up the line. I used to be one of those people and I just don't trust them to automatically make a product that works as people with common sense will expect it to.
 
iamtheari said:
And no matter what, I'm not going to say I am "radar equipped" unless I have an actual realtime radar system on the plane.
Click to expand...

Reread. No one actually said that. My response was that I was "ADS-B radar equipped". The controller knew what that meant.
 
flyzone said:
Reread. No one actually said that. My response was that I was "ADS-B radar equipped". The controller knew what that meant.
Click to expand...
Your original post said that you weren't sure if you were "radar equipped" or not. I didn't mean to imply that you had claimed you were, just to say that I am sticking with my original answer, which is that "radar equipped" is inaccurate in your situation.
 
In practice I've used the heck out of datalink weather. You're not supposed to use it tactically, true, and for good reason. It so happened I had great, modern radars with large dishes in the planes I was flying with that datalink weather but even so, there was almost never a time the NEXRAD imagery wasn't plenty good enough for me to make good deviation decisions.

In my personal aircraft all I have is datalink (via UAT.) Until recently I would cross-check the datalink with the Stormscope, which provided correlation of the datalink presentation with reasonable accuracy. "I think this huge nasty cell is here... (finger on the iPad) so I should see a big conglomeration of Xs about here (points to WX-900)."

But then my Stormscope died. It sits there forlornly, with an "Inop" sticker on its face. I'd really like to have it back, because when I can match up the presentations, it gives me great confidence about where the cells are in relation to my aircraft. But the repair bill for getting something so old working again has given me pause. Still debating whether to buy someone else's old "working - as removed" Stormscope or just stick with the datalink weather. It seems like I'm messing around with endgame alternatives on the Stormscope. The WX-900 is pretty old and replacing it with a different model is also cost-prohibitive.

Spherics devices are limited in that they're very good at showing azimuth of returns but not so much at their range. A Stormscope on its own is certainly a beneficial tool in many circumstances, but when you pair it up with cockpit datalink weather imagery it really shines, so to speak. I've been bouncing around in the grey area, thinking maybe the UAT weather is good enough now.
 
Oh. And when asked that question I usually just say "Negative, datalink weather only." Like someone else here said, the question is more of a coded word of caution than anything else.
 
Ryan F. said:
Oh. And when asked that question I usually just say "Negative, datalink weather only." Like someone else here said, the question is more of a coded word of caution than anything else.
Click to expand...

Thanks for that. Most informative.
 
Fearless Tower said:
You must have had a really good stormscope. The one I had in the Baron gave way too many false alerts to be reliable.
Click to expand...

Probably not -- just the same as everyone else I imagine. Interpreting the data is the trick.
 
Fearless Tower said:
Interpreting has nothing to do with it. You have to receive data to have something to interpret.
Click to expand...

If your point is that the Stormscope data is a bit tricky to interpret, I would agree. But once you get the hang of it, esp. if you can constantly compare it to other inputs (ADS-B, visual, ATC, radar when available) then over time you get a pretty good idea of how to use it. The greatest thing about Stormscope, which is not commonly known, is that by avoiding all dots, esp. ones with "radial spread", you will not only avoid rain and thunderstorms, but also turbulence, since there are dry (and often invisible) atmospheric discharges which it detects while radar and ADS-B etc. miss. Bottom line: used properly and in conjunction with other inputs, Stormscope can keep your ride smooth, if you want it to.
 
RotorDude said:
If your point is that the Stormscope data is a bit tricky to interpret, I would agree. But once you get the hang of it, esp. if you can constantly compare it to other inputs (ADS-B, visual, ATC, radar when available) then over time you get a pretty good idea of how to use it. The greatest thing about Stormscope, which is not commonly known, is that by avoiding all dots, esp. ones with "radial spread", you will not only avoid rain and thunderstorms, but also turbulence, since there are dry (and often invisible) atmospheric discharges which it detects while radar and ADS-B etc. miss. Bottom line: used properly and in conjunction with other inputs, Stormscope can keep your ride smooth, if you want it to.
Click to expand...
My original comment/complaint had nothing to do with interpretation. My only experience with a stormscope was in my Baron. It would often show tons of activity 200 miles away and nothing where I could visibly see convective activity.
 
Fearless Tower said:
My original comment/complaint had nothing to do with interpretation. My only experience with a stormscope was in my Baron. It would often show tons of activity 200 miles away and nothing where I could visibly see convective activity.
Click to expand...

In that case it was broken. What did it show in test mode?
 
Fearless Tower said:
My original comment/complaint had nothing to do with interpretation. My only experience with a stormscope was in my Baron. It would often show tons of activity 200 miles away and nothing where I could visibly see convective activity.
Click to expand...

Yes, that's a different matter altogether -- that's simply a unit which needed servicing. A functioning Stormscope/Strikefinder will still inherently show 'flawed' but real-time data, and it's the instantaneous report of that data which makes it valuable. As mentioned earlier in the thread spherics is a sensing technology not inherently accurate on its own; it's good in azimuth, but not particularly good in range, among other issues (sensing or not sensing various weather phenomena you might expect it to display.) The best use of the Stormscope is to correlate other sources and make decisions about the weather's precise location based on all of the factors.
 
You must log in or register to reply here.
Back
Top