ADS-B Weather

[TWinter]

I know the discussion has been brought up before, but I never thought about the actual real-time delay of ADS-B weather. This month's MAPA magazine has their accident report write-up. While we always hate to hear about fatalities, especially other Mooney drivers, but it is always beneficial to learn from them. I've been up and down the fence about canceling my XM subscription since having the GDL-88 installed, but I've always hesitated because I've heard the weather on ADS-B is "slightly" delayed, Even more so than XM, and honestly, I like having the XM radio.

I read the accident report in the Mapa Log and see the NTSB determined a major factor in the accident was the fact the ADS-B weather displayed to the accident pilot could have delayed as much 15-20 minutes. That's quite a length of time. Enough for them to conclude that it was a major factor in the accident.

Some of you guys may know more about the accident and the accuracy of the NTSB findings. But this really gives some new perspective about hanging onto the XM weather subscription and keeping the 796 portable up to snuff..

Just something to keep in mind. Our Mooney's are fast, we can cover lots of ground in 15-20 minutes. What we actually encounter when we get there and what's on the screen might be totally different. Whether using XM or ADS-B always remember there will be a lag time...up to 20 minutes.

 

-Tom

 

 

[gsengle]

Others may know better but I don't find ADS-B weather to have any greater lag than XM did... It does have slightly less resolution. Personally I wouldn't use either to pick my way through tight spots...

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[Bob_Belville]

Just now, gsengle said:

Others may know better but I don't find ADS-B weather to have any greater lag than XM did... It does have slightly less resolution. Personally I wouldn't use either to pick my way through tight spots...

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I switched from XM weather (displayed on a GPS696) to ADS-B NEXRAD (displayed on a GTN750) 3 years ago. I agree that there seemed to be little difference. I do no depend upon NEXRAD for tactical decisions. It is very helpful for more strategic planning further ahead.  Further, I have not found that NEXRAD colors tell much about what your ride will be like. Now my trusty Stormscope is a different matter. She's never lied to me. 

(I still have XM radio on the 696. The subscription for that piggy backs on my car XM.) 

[M20F]

ADS-B and XM are both strategic, not tactical.  The moral here is don't use either for tactical avoidance.  

I have used both XM and ADS-B and from my perspective no real useful difference between the two.  

[carusoam]

Expect that the XM is going to lag enough that it is still the big picture that is good for planning purposes. The 'tactical' device is the storm scope in your instrument panel.

Both XM and ADSB should be displaying the time that the image was taken. (Edit: Not neccesarily true)

While on the ground...   I am a big fan of playing a series of radar images to get a feeling for strength and direction.  The latest radar images that I get on my cell phone on the ground give speed and direction of the cells along with the tops....

Has anyone seen this capability in the air?

Best regards,

-a-

I have been proven to be the slower typer....

[Marauder]

22 minutes ago, carusoam said:

Expect that the XM is going to lag enough that it is still the big picture that is good for planning purposes. The 'tactical' device is the storm scope in your instrument panel.

Both XM and ADSB should be displaying the time that the image was taken.

While on the ground...   I am a big fan of playing a series of radar images to get a feeling for strength and direction.  The latest radar images that I get on my cell phone on the ground give speed and direction of the cells along with the tops....

Has anyone seen this capability in the air?

Best regards,

-a-

I have been proven to be the slower typer....

I had my WX-500 installed last summer and got to see it in action during stormy weather with a Garmin GDL-39 providing FIS-B. I did see lightning strikes show up ahead of what the FIS-B was displaying. I'm pretty sure it was due to the lag.

I also flew once low enough to pick up radar through an app called Storm. Even Storm has a slight delay in broadcasting "live" radar. Here is a picture of a radar viewed at 9:45 EST. The actual radar broadcast was 9:36 PM EST. 

The lesson is that unless you are flying with onboard radar, the data can be aged.

[Deb]

Scott Dennstaedt has discussed this issue here: https://www.avwxworkshops.com/forum/read.php?8,550.

The NTSB issued this safety alert which suggested that satellite weather displayed in the cockpit could be as old as 15-20 mins: http://www.ntsb.gov/safety/safety-alerts/Documents/SA_017.pdf

Scott's point was that might be true for FIS-B weather, but it was an overstatement for the providers WSI and WxWorks.

[Hank]

I thought both XM and ADS-B weather suffered the same "up to 15-20 minute delay" caused by knitting together the many small radar sites to give the country-wide overview. Both are tactical, so you don't need to use the StormScope for strategic evasion. But it's nice to have the SS anyway!

[carusoam]

The on the ground app I was using was ZoomWeather.  Brought to us by none other than weatherTAP.com... TAP=Trade-a-Plane...

It shows the time of the data up by the time on your cell phone.  My weather on the iPhone is currently 7 minutes old as I type this message.  This app is great while you sit at a softball game trying to determine when the next lightning strike will occur.

Since this is not necessarily an aviation reliable source.  I would expect one that is should be displaying the data's time as well.

Looking at WingX using internet delivered data.  The weather loop can be selected for 5 or 15 minute intervals.  The last data shown is the most recent.  It ages while you are looking at for a couple of minutes.  Wing X clearly shows the time of each plot.

the good news: Internet delivered weather through WingX is indicating only a couple of minutes of age.

Question: Is the time stamp believable?  Scott Dennstaedt (D's post above) says it may be off by up to 20 minutes.

The bad news: the time stamp might not be reliable enough, according to Scott D.

Best regards,

-a-

[Piloto]

I used to have XM/WX on my Aera 560 but dropped off the subscription and switched to WX on my Samsung Smartphone with the Garmin Pilot. Below 10,000 feet I get wx updated about every 10 minutes. Below 5,000 feet about every 5 minutes. Best part is that on my way to the airport I can see what the weather enroute is going to be like. The other advantage is that it works anywhere in the world were there is internet access. In the caribbean area internet WX is the only way to get WX. 

[carusoam]

Piloto,

does your screen show both the time of day and age of the data?

This WingX screen shot indicates time of day = 10:51  data 10:50:30 (pretty close together)

Sounds like 15 minute old data may have been assembled and then broadcast at 10:50:30...

Best regards,

-a-

 

[Piloto]

Carusoam

On the lower right corner it shows the time of the last update, either UTC or EST. It can also show the moving weather trend, but takes longer to download. The weather correlation is pretty good, specially when on approach.

 

[Marauder]

The on the ground app I was using was ZoomWeather.  Brought to us by none other than weatherTAP.com... TAP=Trade-a-Plane...

It shows the time of the data up by the time on your cell phone.  My weather on the iPhone is currently 7 minutes old as I type this message.  This app is great while you sit at a softball game trying to determine when the next lightning strike will occur.

Since this is not necessarily an aviation reliable source.  I would expect one that is should be displaying the data's time as well.

Looking at WingX using internet delivered data.  The weather loop can be selected for 5 or 15 minute intervals.  The last data shown is the most recent.  It ages while you are looking at for a couple of minutes.  Wing X clearly shows the time of each plot.

the good news: Internet delivered weather through WingX is indicating only a couple of minutes of age.

Question: Is the time stamp believable?  Scott Dennstaedt (D's post above) says it may be off by up to 20 minutes.

The bad news: the time stamp might not be reliable enough, according to Scott D.

Best regards,

-a-

I think that's where pilots get into trouble. AOPA had a nice safety video of an accident in Texas of a Piper who appeared to be relying on ADS-B weather to fly around a cell. 5 minutes is an eternity for a fast moving T-storm.

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[midlifeflyer]

1 hour ago, Marauder said:

I think that's where pilots get into trouble. AOPA had a nice safety video of an accident in Texas of a Piper who appeared to be relying on ADS-B weather to fly around a cell. 5 minutes is an eternity for a fast moving T-storm.

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On top of that, I'm pretty sure the age shown is the age of the last update to the system, not the age of what is actually out there in real time. 

[Bob - S50]

If you are thinking about installing the GDL88 you might consider the new GTX345 instead.  Since you are considering adding the GDL that implies you already have a GNS or GTN (or something better) otherwise you wouldn't be able to display the FIS-B or TIS-B data.  If that were the case, I'm thinking you meant the GDL84 which is wifi to your tablet rather than hardwired to your GPS.

The GTX is supposed to be able to display the same data on your GPS as the GDL.

The GTX replaces your transponder rather than just adding a box.  Saves your useful load.

The GTX will also give you a bluetooth display of the FIS-B/TIS-B on a tablet with either Garmin Pilot or Foreflight.  The GDL won't.

The GTX will give you an AHRS (emergency but not legal) attitude backup in Garmin Pilot.  The GDL won't.

The GTX will give you 1090ES out so you can use it anywhere in the world.  The GDL won't (it uses 978 out).

The GTX is available in a remote version that can be controlled by a GTN.  If you do that and remove your current transponder, you just freed up some panel space.  Personally, I prefer to have the panel mount rather than the remote.  That way, if the GTN dies, I can still control the GTX.

Think of the GTX345 as a GTX330/ES, GDL88, and Flightstream 210 (minus the flightplan transfer) all rolled into one box.

[steingar]

Anyone using either XM or ADSB for anything other than strategic planning is placing a fool's bet.  Neither is sufficiently current to be in the running for "real time".  ADS-B isn't slow enough to justify an XM subscription in the house of Steingar.  Indeed, I was ever so glad to cancer my XM subscription.  I doubt I've ever seen  more dysfunctional company.  ADSB would have to be woefully slow and inaccurate to justify it, and even then I'd have pause.

[TWinter]

8 minutes ago, Bob - S50 said:

If you are thinking about installing the GDL88 you might consider the new GTX345 instead.  Since you are considering adding the GDL that implies you already have a GNS or GTN (or something better) otherwise you wouldn't be able to display the FIS-B or TIS-B data.  If that were the case, I'm thinking you meant the GDL84 which is wifi to your tablet rather than hardwired to your GPS.

The GTX is supposed to be able to display the same data on your GPS as the GDL.

The GTX replaces your transponder rather than just adding a box.  Saves your useful load.

The GTX will also give you a bluetooth display of the FIS-B/TIS-B on a tablet with either Garmin Pilot or Foreflight.  The GDL won't.

The GTX will give you an AHRS (emergency but not legal) attitude backup in Garmin Pilot.  The GDL won't.

The GTX will give you 1090ES out so you can use it anywhere in the world.  The GDL won't (it uses 978 out).

The GTX is available in a remote version that can be controlled by a GTN.  If you do that and remove your current transponder, you just freed up some panel space.  Personally, I prefer to have the panel mount rather than the remote.  That way, if the GTN dies, I can still control the GTX.

Think of the GTX345 as a GTX330/ES, GDL88, and Flightstream 210 (minus the flightplan transfer) all rolled into one box.

If you were asking me?..I have GDL88 w/ GTN 750. In conjunction I have also been using my 796 portable to display weather and use the GDL88 primarily as traffic display on the 750. For some reason I had it in my head that XM weather was marginally more accurate as far as "real time" over the ADS-B. Maybe that was the case before all the towers were put up and the coverage has improved so much more. I realize  there is a delay on both XM and ADS-B, but seems that the XM was slightly better. Apparently, not so much.

I took two trips this past summer from Tennessee to Maine and back. The XM weather worked well and the timing was not far off. As all have mentioned, majority of my weather briefing and planning was done on the ground well in advance of actual departure time. XM pixels and image depiction on the 796 seems much less blocky over the GDL.

Maybe it's time to do a real time comparison of the GDL and the XM. If they are the same of only within a few minutes in difference I'll probably drop the XM. As most all agree it's best to do your planning on the ground and just use the in the air data for the overall picture.

 

-Tom

[Danb]

I also have a storm scope for determining the current status of potential thunder. I've had xm since it came out and Adsb via Stratus for a couple yrs. Since I do like xm better both xm and Adsb being dated I just (yesterday) and cancelled my xm subs. Hopefully I didn't make a mistake. They did offer me like six months free if I Paid for it a yr in advance that's creepy. I assume I'll only be giving up weather views on the ground? Who ever dropped there xm for Adsb would you do it again and is the Adsb comparable to the xm?

[DonMuncy]

I liked the XM weather best, but I didn't like paying for it.

[M20F]

49 minutes ago, DonMuncy said:

I liked the XM weather best, but I didn't like paying for it.

What do you like better about XM versus ADS-B?  Sincere question because I really don't see much appreciable difference other than range.

[carusoam]

XM graphics are less blocky. The colors are a bit different.  Includes entertainment...

Both indicate places to be avoided equally well.

Both have inherent time delay issues.

XM works in the hangar.

ADSB often takes being off the ground.

The way I looked at it...

Cell phone or wifi delivered weather while on the ground.  No additional monthly costs.

ADSB while in the air. No additional monthly costs.

Storm scope for knowing where the lightning strikes are in real time. No additional monthly costs.

I like to stay really far from all the colored spots and prefer to avoid the extra monthly costs.

Fair weather flyer,

-a-

[Oldguy]

Dropped my xm and have gone solely with ADS-B wx in the air. Stormscope tells me what to avoid along with using the ADS-B weather as a longer range planning tool (strategic) while in the air.

On the ground, it is a wx brief before pre-flight and them a MyRadar (iPad/iPhone app) for a rolling 20 minute view of what has been happening while letting the temps come up. As a plus, MyRadar has an aviation layer you can turn on to show a filed flightplan on their map. And the price for the app is right in line with being a CB - free!

John

[TWinter]

2 hours ago, Oldguy said:

Dropped my xm and have gone solely with ADS-B wx in the air. Stormscope tells me what to avoid along with using the ADS-B weather as a longer range planning tool (strategic) while in the air.

On the ground, it is a wx brief before pre-flight and them a MyRadar(iPad/iPhone app) for a rolling 20 minute view of what has been happening while letting the temps come up. As a plus, MyRadar has an aviation layer you can turn on to show a filed flightplan on their map. And the price for the app is right in line with being a CB - free!

John

I also use MyRadar Pro App. Works very well on the IPhone 6+.

[DonMuncy]

Everything Carusoam said.

[PTK]

On ‎2‎/‎17‎/‎2016 at 10:25 PM, Hank said:

I thought both XM and ADS-B weather suffered the same "up to 15-20 minute delay" caused by knitting together the many small radar sites to give the country-wide overview. Both are tactical, so you don't need to use the StormScope for strategic evasion. But it's nice to have the SS anyway!

Stormscope is definitely my first choice. But it is very nice to have both.

Two challenges with radar. Delay, and only shows precipitation. Stormscope shows lightning in real time. Every thunderstorm generates lightning present in the cumulous and mostly in the mature stage. Radar shows precipitation. Precipitation is present in the dissipating stage of a thunderstorm. Therefore any ts related precipitation on radar hints a dissipating ts.

Having both radar wx and stormscope gives a more complete picture. The thunderstorm building in real time, and, although with a delay, the dissipating trend.

It's interesting that a ts can build, mature and dissipate in as little as 20 minutes which is about the the delay of radar info.