Geico266

Geico266

Well Known Member
While flying cross country yesterday I decided to get on top from San Antonio and fly over the snow storm in Kansas. The "Echo Tops" on the XM Weather said 10K max along my flight route. Being the good VFR pilot that I am ;) I called up Flight Service to double check the levels. Flight Service had the tops at 20K. :eek: We had O2, but as you know above 18K is IFR only. :eek: so we had to divert to Amarillo where it was clear as a bell.

BTW, I am stilling trying to finish eating the 72oz steak served at "The Big Texas Steak House" in Amarillo. Talk about Texas portion size! :rolleyes:



1. Has anyone else seen this problem with accuracy and XM reporting Echo Tops? There was cloud data missing yesterday, maybe that was the problem? I have noticed weekend data seem less accurate.

2. What is your choice of flight planning info you use for checking tops of clouds?
 
Echos are actual radar returns, where as the actual cloud coverage may extend significantly higher. So the snow may have been radar significant only as high as 10K. Thunderstorms will have echo tops that reach up into the 50's as they have the convective activity to move rain and hail that high, which are also much more radar significant.

PIREPS and/or forecast may have pushed that 20K number for actual IMC conditions.

Just a theory based on past observation.

For preflight planning, check for forecastwinds and temps aloft, as well as Airmets for IMC conditions. Those will usually give you a pretty good preflight picture.

Edit: by the way, next time head to Coyote Bluff and get the burger from ****. It (and the rest of their burgers) are phenominal.
 
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when i look at weather products, either through XM, the internet, or hearing them from a live briefer, I rate them for accuracy in the following order.

I figure that Nexrad is fairly accurate, METARS are pretty good, TAF's are about 70% accurate for sis hours, winds aloft forecasts give me a general idea of the direction of flow, but magnitudes are a "guideline". Just about everything else falls into the "show it to me, and I'll believe it" category, including XM cloud reports (they are really pretty far off, especially around West Texas).

Weather is what we get, not what we want it to be, or what is forecast, and I am always pessimistic about the forecasts....

Paul
 
radar tops and xm

The previous poster was right on about actual tops and radar tops. Be very careful when using xm radar around TRW's. I don't know of a single airline that uses that product to circumnavigate storms. I will take my on board radar and years of experience with it any day. I have had my dispatcher tell me I can top an area of storms when in fact they are much higher than what he is seeing on xm.

one reason why, you can have strong storms in the west that are highbased and very little rain that won't show up on xm but will paint on an airborne set with the gain turned up. About the only time I wish I had xm on board is when trying to decide whether to go north or south of a long
east/west line.

cm

I know RV's dont have radar on board, just making a point..
 
I can see I need to "adjust" my preflight plan. Clearly, it was not adequate based on what I found in flight.

Thanks one and all, for the tips.

I can see an IFR ticket in my future. Sure would have come in handy yesterday.
 
XM in the cockpit is great but not exceedingly real time accurate especially when it comes to echo tops and Satellite Mosaic. It is a good strategic tool but not an excellent tactical aid.

Like anything else you need to use it for awhile to learn it's strengths and weaknesses.
 
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