XM is still better

Last week I departed an airport with rapidly developing thunderstorm cells in the area. My trusty old panel mounted 396 was showing the nexrad radar as soon as I taxiied to the runway. One cell 13nm away, very easily avoided. Nothing on the iPad obviously until airborne. I have a Stratus ESG combo which uses the transponder antenna for receiving FIS-B. I made the trip VFR at 3000ft and never did get a full picture of the situation with banding on the radar presumably not being line of sight to a ground station.

Weren't we supposed to get hi-res nexrad by now via FIS-B? Returns still look like Minecraft blocks. I keep the firmware in the Stratus updated to the latest.

Has the FAA stopped installing ground stations? Coverage in my area is spotty down low no matter what airplane I'm in.

I use an ipad with cellular. Just before T/O I am using the cell signal to get radar. Then the 3+ minutes to get adsb radar is not so bad. Though at my airport (8 mi from ORD) the signal is so strong, I get FIS data on the ground.

Larry

rocketbob said:

Weren't we supposed to get hi-res nexrad by now via FIS-B? Returns still look like Minecraft blocks. I keep the firmware in the Stratus updated to the latest.

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Out of curiosity, were you set up for CONUS or Regional?

I live in the Sacramento Valley just northeast of the San Francisco bay area. Large swaths of the valley have zero ADS-B coverage below 2500', still. Despite a large training aircraft presence in the area. Doesn't seem like they are in any hurry to add towers, even in heavily populated areas.

Must be a local reception thing - out here in the middle of nowhere I actually see 2 ADSB towers on the ground, and usually have my regional radar before reaching the runway. I've had excellent results from it.

Opposite opinion

In the RV-10 I seldom fly below 8,000' except on very local flights, and then, who needs on-board wx radar? Up at 8,000' (and usually higher) I've always had good coverage. OTOH,....My experience with XM has been disappointing. I still have it for music (car and airplane) and I get "need re-fresh signal" so often that I've bookmarked the web site in my iPad. But the one time I really wanted it (crossing desert SW with scattered lines of TW) it wouldn't work ("need re-fresh") and I was out of internet range for the iPad so I couldn't refresh until we landed. I won't pay $400/yr for this sort of service, so I dropped it and have never regretted it.

bjdecker said:

Out of curiosity, were you set up for CONUS or Regional?

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Regional.

Most of my trips are short ones at 3000ft and its very hit or miss. Sometimes FIS-B works well, sometimes not. Its unreliable enough for me I can't trust it. Yes XM costs me $35/mo and I hate their customer service, but when you're sitting at the runup area looking at lightning off in the distance and dont want to fumble around with terrestrial weather on a phone or flipping wifi etc.

I also remember that years ago when ads-b started they touted future versions would have more detailed nexrad. Why is that still not the case?

rocketbob said:

I also remember that years ago when ads-b started they touted future versions would have more detailed nexrad. Why is that still not the case?

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Not sure I remember that. But I've been able to compare ADSB regional and XM side by side. The regional version is pretty good. True, XM "looks" a bit better, and might handle the vertical integration better, but it is mostly an illusion. Given both systems have some latency (time delays at times up to 20 minutes) any information more detailed than the ADSB block size cannot be trusted to still be true at the current time. So to get any real increase in detail you have to get the NWS data compiled/uploaded faster, somehow.
Now, the ADSB radar data more than 300 nm away looks like cr... due to the blockiness. But the same caveat applies. The block size is a reasonable representation of the uncertainty of the data, given that you won't get there for another hour or two.
I have no idea how much time is actually consumed on 978 MHz for these uploads, but I think it's signifiant, so I wouldn't hold out much hope for better resolution in the national picture to happen - unless they move it to a dedicated frequency. Then we all get to buy new receivers.
My plea for an upgrade: Who decided it was good to attach a time since last uplink? It would be much more useful to attach the time to the oldest actual NWS data sweep within 300 nm.

As long as I'm VMC and have pretty good assurance that the red blob of depicted weather is not moving straight at me, I aim at it or just to the rear of it figuring that it's already moved from the depicted spot on the ADS-B. But, as long it's not mountainous terrain, my best thunderstorm avoidance is done in VMC below the cloud bases, typically 1500 to 2500 AGL. At those altitudes, you don't need ADS-B to avoid the precip areas.

I don't even consider trying to deal with thunderstorms while on an IFR flight plan in IMC. ATC tries to help, but are typically not flexible enough to keep me from getting beat up by the turbulence.