XM\WX vs ADS-B WX

[Piloto]

On the AOPA June 2102 issue page 88 there is a comparison table between the two systems. I noticed that they indicate that the radar update for XM is 5 minutes while for ADS-B is 15 minutes. How can a 15 minutes update be useful when I have seen here in Florida thunderstorm with a 15 minutes life span. Also there is no satellite depiction for ADS-B. I found XM satellite to be very useful specially when there is no precipitation or when flying over the Bahamas. 

Has anyone done a side by side comparison between the two systems?

Although there is no subscription for ADS-B Wx the fact is that you are not getting anything better over XM on a Garmin 796 that includes a full array of navigation capabilities plus the reliability of Garmin products. As an example just try your iPad on direct sunlight vs any of the Garmin portables. It is quite obvious that Garmin flight test their products but not so for iPad manufacturers where it is not required.

José   

[jetdriven]

They probably say that because XM is a major advertiser in their magazine.

ADS-B CONUS images are updated every 15 minutes while local NEXRAD images get updates every 5 minutes.  Correct, ADS-B has no satellite image.   But, ADS-B also has NOTAMs, and SUA(MOA, etc) status.  Further, ADS-B requires no subscription, is highly portable, and can be used by more than one user with one ADS-B unit. The ADS-B unit such as the stratus and Clarity can also run 8 hours from an internal battery.

Finally, several people have lost XM coverage when they need it most, navigating around a supercell thunderstorm and the XM loses the satellite signal behind the cloud. Plus, al least one person on Beechtalk has reported the unit will not load data due to it thinking the subscription has expired.

I am not trying to knock XM, but there is a lot of noise out there probably sourced from XM, about how ADS-B is so much more inferior than their product.  Well, not paying their subscription for a year has bought the ADS-B box for me.  Another year, they pay for my iPad as well.

Here is the XM and ADS-B side by side.  The XM is digitally smoothed but the image is the same. Actually, the ADS-B paints a red dot in the middle of the cell off the nose.  Note they are both on a :03 update time as well.  Depending on a lot of things, the NEXRAD latency might be higher through the ADS-B ground network or the satellite.

[Jerry 5TJ]

Keep in mind that you can get XM services anywhere you can see the sky, whereas ADS-B requires some altitude, and the transmitter network is still being built out.  Here is the FAA's coverage map for the end of next year, 2013:

 

 

SOURCE:  http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/surveillance_broadcast/coverage/

[gjkirsch]

I sat through a 3 hour weather seminar for pilots last month.  If I understood it correctly, the refresh rates vary with the weather situation in a given part of the country.  So, if it is blue sky and nothing happening, the refresh rate is 15 minutes, if it is an unstable area, then the refresh rate is 3 or 4 minutes. 

[M016576]

Judging by the map of coverage above, looks like those of us that don't fly up in the oxygen-on-o-sphere in the pacific north west are still at a disadvantage when it comes to ADSB.  Looks like I'll have to keep paying the gouging XM WX prices for the near future

[jnisley]

I've used XM Weather displayed on an MX20 for a number of years, it has never failed me in flight but occasionally I've needed to re-activate receiver if not used for several month. It's basically a phone call with several auto prompts. The "free" in ADS-B is very attractive after paying $165 per quarter for XM all these years.

[pilot716]

I have just ordered the stratus and it is said to be shipped on or around the 5th of June. I currently use XM on the 496. I fly alot of IFR and use the iPad. I will issue a full pirep after using the unit for a few flights.

[M20E-1964]

I think it's a no brainier.   I could have 2 iPads for the price of a comparable garmin.   Foreflight kicks but.   I sold all my garmin stuff and couldn't be happier

[M016576]

Quote: gmcd

I think it's a no brainier.   I could have 2 iPads for the price of a comparable garmin.   Foreflight kicks but.   I sold all my garmin stuff and couldn't be happier

[pilot716]

I flew last night and had the Stratus on Board for the first time. It worked just as advertised. I believe it became active around 800' msl.

You receive the same wx info on the ipad via FF, that you would on the ground. My co-pilot even tested his iPhone and had no problem receiving the same info. There was not much wx out there other than some lower ceilings above us which I captured on the iPad pic and some rain south east of our track.

The 2nd pic is of the Stratus status app. it is some basic info the most important being battery life.This pic was taken on our return trip, the battery shows 62%, When I started the flight it was only at 80%. ( I had charged it when I first received it a few days ago, but did not recharge before flight) Over all I was very happy with the unit.

Regards,

Mark

[KSMooniac]

ADS-B still has a gaping hole in their coverage in the dynamic plains states, so it remains a no-go for me.  I'd love to ditch the XM subscription price, but it works well, especially where I currently live and fly.  I also really really appreciate the superb integration of Garmin's 496 (or later units) and GXM30 antenna/receiver that run all the time off my ship's power.  No need to mess with chargers, bluetooth, wifi, etc.  I'm not looking forward to managing that stuff with an ADS-B solution in the future, but to save $55/mo I suspect I'll get over it.

[KSMooniac]

I'm still spoiled by being able to leave the device in the plane and just have it work when I power up.  I hate having to "manage" something like that which would require removing from the plane and charging it at home.  I'm still keeping an eye on this new stuff, though, and hope we'll get a "portable" box that can run on ship power and seamlessly integrate with a tablet of some sort... like my current Xoom so I won't have to buy an iPad. 

[aviatoreb]

Quote: KSMooniac

ADS-B still has a gaping hole in their coverage in the dynamic plains states, so it remains a no-go for me.  I'd love to ditch the XM subscription price, but it works well, especially where I currently live and fly.  I also really really appreciate the superb integration of Garmin's 496 (or later units) and GXM30 antenna/receiver that run all the time off my ship's power.  No need to mess with chargers, bluetooth, wifi, etc.  I'm not looking forward to managing that stuff with an ADS-B solution in the future, but to save $55/mo I suspect I'll get over it.

[1964-M20E]

Where I fly here in the SE I have no problems picking up ADSB weather usually by 1500' and < 5 minutes after takeoff I am receiving information.  Traffic is another story I do not have a Mode S transponder and the Sky radar traffic feature utilizing ADSB does not work well at all.  I do have the I-fly 720 and the Sky Radar and they are plugged into the airplane power with a separate battery backup.  I like the weather I get on the screen and it helps tremendously.  You do need to remember that all systems have a delay in the data and it is not live radar.

[FlyDave]

I have been using ADS-B for over a year with both WingX and SkyRadar.

I flew from Raleigh, NC to Long Beach, CA earlier this year and had no coverage for over 1,000 miles.

I'm going to Oshkosh then New York and finally back to the Los Angeles area later this month and I've made the decision to activate the XM weather subscription on my G496 for this trip. The holes in ADS-B coverage are too large and WingX is still too flakey with ADS-B for this trip. Having the peace of mind of knowing were the weather <<WAS>> is worth the money.

When ADS-B "comes of age" I'll use it where there is coverage (in CA) but as of right now, IT AIN'T THERE!

[Piloto]

Dave you are not the only one with similar ADS-B experience. Like GPS one thing I like about XM\WX is that you do not have to fly the plane to know that is working. I get XM\WX inside the hangar and can plan my flight before I pull from the hangar. For traffic I prefer plane to plane link rather than TIS or UAT/ADS-B. With the Monroy ATD-300 I know the thing is working before I pull out of the hangar by detecting local traffic. With ADS-B you need to be airborne, within coverage and traffic in the vicinity to know if it is working. Just the fact that you can not check ADS-B functioning on the ground before flight does not give me much confidence. It is like not doing engine run up before take off.

José