Garmin weather downlink

[Todd Peterson]

After having just flown to Palm Springs and back I now have enough time using our new Garmin GDL49 weather downlink to make an informed report.

On the new 230SE that we just built up we decided to go with a Garmin 530 and the weather downlink instead of a WX950 stormscope. The price of the weather downlink was around $3,500 vs $7,500 for the WX950. The GDL49 uses a subscription based service which will run from $9.00 a month plus a dollar for each download to about $50 a month for unlimited downloads.
I elected to opt for the ulimited downloads as I knew that I would be playing with it, maybe flight testing would be a better term, a lot in the near future. As it turns out that was a good choice considering the weather out and back that I had for the trip.

In this first installment I would like to point out the negatives that I found with this installation. In the next installment I will break down the trip so you can see where the positives come in and how versatile the system is for things other than thunderstorm avoidance.

I would not use this system for flying through an area of active and building thunderstorms. The detail is not quite sufficient for that and it takes a little too long to get the information and by its very nature it is somewhat dated. The nexrad picture is updated every six minutes and then it will take another three or eight minutes to get it to your screeen. Fortunately the system has an auto request function so I found that by making the request on the ground, prior to departure, and then dialing in an autorequest for every ten minutes it solved that problem.By the time I had lifted off somewhere in the climb the info would come up to be automatically updated every ten minutes.

A WX950 on the other hand gives you real time information and has much better detail if you are in the middle of a developing line of thunderstorms or are about to enter one. If this is what you are going to be doing it's a no brainer, the WX950 is the way to go. In addition once the WX950 is installed there is no further monthly fee's. On top of that you do not need to have a Garmin 430 or 530 installed to use it. Obviously you would still need an MFD, like the MX20 to use this service through other providers.

Next time I will briefly relate the weather problems associated with my trip to the AOPA convention and how the GDL49 fit into the picture.

[Todd Peterson]

Now for some of the good points about the GDL49 weather downlink.

When I departed El Dorado departure had asked for a ceiling report so I was watching close. I hit the clouds at eighty feet and was solid at one hundred and fifty feet so it was fairly low. As I came out the top my most pressing desire was to find an area of better weather in case a problem should crop up with the airplane. I hate to say it but as an aircraft mechanic you sometimes get a little paranoid about things. Here's where the weather downlink really comes in. Prior to my departure I had requested not only the nexrad information but also a graphic metar display for a 250 nm radius around my present location. Once out the top the information was at hand and literally within 30 seconds I had a complete picture of the surrounding weather in terms of ceilings and visibilities. I knew that if I had a problem there was an area of marginal VFR about thirty miles northwest of my present location. It was very comforting and the display they have for the graphics works very well.

On my return flight from Dalhart back to El Dorado it was IFR all the way and in some areas it was low IFR. By being able to either look around my present location or 250 nm ahead of my present location I had a good picture of the total weather situation. It was very comforting and gave me many options that would have been difficult to piece together by talking to Flight Watch. If El Dorado had been below minumums it would have made the final decision as to my alternate a lot easier.

The graphic metar feature was also used as Jo and I negotiated the mountainous area between Phoenix and ABQ while VFR. The weather wasn't all that great but having a complete weather picture of all reporting points came in mighty handy.

The downlink also lets you plug in airport identifiers and it will provide you with a text form of the airports latest metar. As we left Palm Springs we had planned on flying through the Prescott area enroute to ABQ as the FSS guys had said it should be flyable. By the time we got a good start I pulled up the textural metar for Prescott and found that there was a fog bank all quadrants with the mountains obscured so we changed our flight plan and headed further south towards Phoenix. Knowledge is a good thing.

The display for the graphic metar and the nexrad information is put on a seperate page with the 530 and I would suspect the same would be true for the 430. It also puts the nexrad information on the nav pages so you can see everything relative to the map. The graphic metars can be pulled up from the map page by running the little airport information arrow to the airport you want to check. When the airport identifier is illuminated the graphic metar then pops up above the airport. Pretty neat.

The graphic metar and textural metar function was worth the purchase price alone. This is one of the things that really separates the GDL49 from the stormscope. The wealth of information it provides goes far beyond thunderstorm avoidance.

Next time we will look at the Nexrad function.

[witrakw]

anyone with any experience with that Satellink weather download? their website mentioned it would be up and operating at AOPA convention. Big difference between "push vs. pull" info from ground cells vs. satellite feeds(active request vs. passive request). I am unclear whether the satellite based systems are quicker since they are passive and what the relative download speeds are. They advertise it for the mx20 display but I don't know for other mfd's or gps displays.

No doubt that this rookie could use all the weather help I can get in the cockpit. If I could have a fairly realtime satellite pic, recent nexrad, current metars and stormscope---maybe i can stay out of trouble.

thanks, bill

[Todd Peterson]

I apologize for being late with this last post but Jo has been taking care of her mother for the last week and things have been pretty busy here.

The nexrad display comes in a couple of ways. There is a separate page to display the nexrad information and on this page you can either have a view that extends around the airplane for up to 250 nm or you can get a forward 120 degree view, similiar to the WX950. This view is nice for its increased detail as you get ready to go through the weather. The nexrad information is also overlayed on both the moving maps eleminating the need to switch back and forth between pages to get all the info.

The first thing you learn is that all the green areas do not necessarily indicate its raining. It might be virga or even a very dense cloud deck with no precip. It's pretty easy to figure out when combined with the graphic metar information. I would say however, that based on my observations, I will tend to stay away from areas that are yellow and most certainly those that are red. Now here's the rub. The stormscope plots turbulence not precipitation, and some of the areas of heavy rain have the least turbulence. With the GDL49 you have to kind of assume that the areas of heaviest precip will be the areas of heaviest turbulence. It kind of stands to reason that this would be the case but the stormscope has the definite advantage in this area. Once again it depends on if you are planning on penetrating an area of thunderstorms or are trying to avoid them entirely.

While IMC it is kind of interesting to be able to see the areas of precipitation and their intensity that surround you. I have never had such a clear picture and it is very informative.

The nexrad function can be brought up as a 250 nm view around your present location, a 250 nm view ahead of your present location and you can also dial in any remote site anywhere and pull up the 250 nm view around that station. You cannot pull up an uninterrupted view of your flight path past the 250 nm limit. You have to think of the view as a series of 250 nm circles along your projected route.

On my trip to Palm Springs, while in the Dalhart area, I heard there was an airmet for convection activity in NM. Scanning ahead 250 nm showed the way clear to ABQ at which point I intended to go south, based on my last FSS briefing. I then dialed up the ABQ nexrad and it quickly showed the area of convective activity to be mainly south of ABQ. I therefore amended my route to go straight across from ABQ to PHX and the route worked well. There was also building activity north of my route up around Gallup so going the north way didn't look all that good either. As I got to ABQ I went to the forward 120 degree view and flew through the area without getting wet. It was also comforting to know that the area of convective activity was about 75 miles deep and beyond it was clear all the way to PHX.

All in all I think the GDL49 (and those equivilant services for the other MFD's) is very useful and worth the money. You just have to realize that they do have some limitations, but at the same time they give you a lot of general weather information. It certainly made flight planning much easier and for non convective IFR work I think it is great. Obviously if one were activily working around a lot of thunderstorms this weather downlink with a WX950 would give you a complete weather picture that would safely permit you to navigate most anything. At this point in my flying career if I had to choose I would probably go with the GDL49 over the WX950.

And I'm sure you have already guessed that Jo is lined up for the installation of a GDL490 for her 260SE. Sometimes having a wife that flies her own airplane can be kind of expensive, but then that's another story.

Fly safe.