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Don't worry if your head is spinning. I can’t tell you how many pilots have called me for guidance on what to buy in terms of cockpit weather. This has prompted me to create this short primer that will take you through most of the issues and decision points that are required to make an informed decision on what to buy. Regardless of your choice, you will be very happy having weather in the cockpit. So let’s get into the details.
Panel Mount or Portable? Your decision to go portable or panel-mounted depends on how wireless you need to get and how many Ben Franklins you have in your pocket. No doubt that the right certified panel-mounted weather is the best solution both technically and ergonomically. But what is the right panel-mounted solution? Obviously, the answer to this question is very subjective and perhaps very personal. My definition of the right solution is one that includes all of the essential weather data that allows you to plot to avoid adverse weather. This includes Nexrad with looping, Airmets, Sigmets, Convective Sigmets, full text METARs, TAFs, lightning with looping, TFRs, pilot reports and the future graphical area forecasts (Jan 2006). Moreover, any qualifying text must also be included. In my opinion, this solution must also encompass a fast processor for redraw and looping, touch screen for easy data entry and option selection and the ability to pan and zoom to other locations without a lot of knob twisting and button pushing. Another key element is the ability to overlay the weather with other panel-mounted elements such as GPS position, flight plan and approaches, terrain, and other database elements. Placing your GPS position in relation to the weather is mandatory to warrant the expense of any weather system, portable or not. Avidyne currently has a certified XM Satellite Radio solution. Given the overall price, this solution has some serious drawbacks. They will not be offering terminal forecasts, echo tops, Nexrad looping or any kind of panning with their initial release. The Avidyne solution provides only two-dimensional shapes for Airmets, Sigmets and TFRs. No text is provided for you to understand the vertical limits or other conditions of these areas. Avidyne says you have to call the Enroute Flight Advisory Service (EFAS), (better known as Flight Watch) for this important information. Every waypoint in your flight plan will have an associated "closest" surface observation. The implications are two or more waypoints may have the same associated observation and that reporting stations not associated with waypoints in your flight plan cannot be immediately accessed. Essentially, you will need to load up your flight plan with bogus waypoints in order to see these observations. Moreover, these surface observations don't include the full text of the METAR. Remarks such as PRESFR, TCU ALL QUADS and FREQ LTG ICCCCG SW are a few examples of what will be missing from the text. Finally, the Avidyne panel-mounted solution has been priced at nearly $8,500 with installation! Adding approach plates for $3,500 brings the cost to over $11,000. You can certainly shell out these big bucks to get less functionality, but don't complain when your portable counterparts are getting more features, tools and weather products added to their solution for free. XM, Orbcomm or other? There are several providers of data for cockpit weather using a couple of different satellite technologies. Orbcomm uses a request-reply concept (also known as “on demand”) and XM Satellite Radio uses a broadcast technology. Globalstar Satellite Telephone Network is yet another solution that employs a satellite phone and is a request-reply technology. XM Satellite Radio provides a continuous source of many key weather products without the need to track minutes. You are billed a flat monthly fee (unlimited data receipt) and there is an initial fee to activate the service (normally $75). They offer two subscription plans including a “lite” version, called Aviator Lite, with limited weather products for $30 per month. The cost for the full service is $50 per month. Aviator Lite gets you most of the essential data except for ground-based lightning (see Stormscope discussion below). You also do not get echo tops, but I do not consider this to be essential data. The Orbcomm and Globalstar subscription prices are about the same, however, there may be minutes to track in addition to a monthly service fee. It seems as if XM Satellite Radio has surfaced as the primary choice and preference of most pilots. A continuous stream of weather seems to be preferred. At this point, XM Satellite Radio is perhaps the best choice as a satellite weather provider.
Tablet/Laptop or PDA? In this discussion I will use the term PC to represent either a tablet PC or laptop PC. Determining your ultimate display device is perhaps the toughest decision to make. The decision to use a PC versus a PDA depends on many factors and there is a significant cost difference if you are starting from scratch; in the end PDAs are cheaper unless you already own an appropriate PC. 1. Sunlight readability. So you have your own PC? If your PC is not meant for use outdoors, you will be sorely disappointed with using it in the cockpit due to poor readability in most sun lit scenarios (especially direct sunlight). There is a solution for this. A company by the name of navAero produces a product called the t-Pad 800. The t-Pad 800 is a remote display (not a computer) that can be connected via USB and serial port to your indoor-use PC. It is a perfect size and has a curved back making it a very comfortable kneeboard and doesn’t take up as much real estate in the cockpit. It is very sunlight readable and fully dimmable at night. The newest version will be a passive display (you will be able to use both a stylus and your finger). This solution is now available. The t-Pad 800 (picture below) is a bit on the pricey side. However, if you were to purchase another PC you would easily spend at least $2,000 or more to get an outdoor usable PC. The t-Pad 800 is a good alternative if you don't want to spend more money on a new PC.
Most PDAs are sunlight-readable. In fact, all outdoor displays require lots of direct light to provide the best display. If you are in a shaded area such as a cockpit, you may find that there is not enough backlight to have a brilliant display. But the display is still fairly readable. 2. Altitude. Very few PCs are completely solid state. As a result, they have a hard disk which is prone to errors or complete failure when exposed to low air pressure scenarios at altitude. While it is unknown about the limitations of each PC, most manufacturers have documented 10,000 feet as the limitation. Does this mean that the PC won’t work above 10,000 feet? Maybe? Maybe not? If you are frequently flying above 10,000 feet, then I would strongly suggest that you find a solid state PC or move to a PDA. 3. Sony U71. This is a PC unit that is smaller than a tablet, but larger than a PDA (picture below). For now, this unit is not of solid state design. So it has altitude limitations just like any other PCs. This unit is a pretty good size compromise and retails for about $2,500 (can be bundled with NAVAirWx, see below). See this web page for the U50/U70 (the U71 is very similar to the U70).
4. Mission. What is your ultimate goal? If you want to eventually end up with an Electronic Flight Bag (EFB) with all of your flight planning tools, approach plates and charts, etc., then a PC is what you want to choose. On the other hand, you can get a NACO approach chart subscription on the PDA as well. 5. Size. A PC (with the exception of the U71) may be a bit large to use in the cockpit. Some of my customers have decided that taking up extra space in the cockpit is worth it, but most have ruled out a PC due to its size. It is very difficult to mount a PC in most cockpits. Many of the PCs generate heat and this can make summer flights a bit uncomfortable with the PC on your lap. The downside to a PDA is that you won’t be able to use your favorite flight planners integrated on the same computer. Although, you may be able to find a rudimentary flight planner for the PDA. Okay, let’s shift the discussion to portable weather solutions, specifically XM Satellite Radio solutions. XM Weather Subscription Services When you talk about XM Satellite Radio and Weather, you will also be speaking about WxWorx. WxWorx is the only company licensed to manufacture the portable XM WX Satellite Weather receiver (sounds like a monopoly, sort of). Given this, you have two subscriptions choices at the moment. WxWorx Lite or More Filling? After much pressure, WxWorx and XM Satellite Radio now offer two subscription levels for weather. Up to now, the only choice was a monthly subscription of $50. Finally, you have a choice of a lesser subscription cost of $30. XM subscription service is ordered separately directly through XM Radio.
Here are the issues: 1a. With WxWorx Lite, the major product you will lose is lightning. Remember, the lightning data received on the XM link is cloud-to-ground lightning from the National Lightning Data Network (NLDN). The key point is that ground-based lightning does not show intra-cloud lightning. Often in many thunderstorms, intra-cloud lightning is dominant especially in the early stages of development and in certain locations in the country such as the Midwest. In fact, in the Midwest, there is 10 times more intra-cloud lightning than cloud-to-ground lightning. 1b. The lightning is represented on a 4 km grid. This is a very coarse grid. If there are 100 strikes in this grid, you only get one lightning bolt symbol displayed. So, there’s no real way to get a sense of the storm’s strength. 2a. If you have a Stormscope, you should seriously think of subscribing to WxWorx Lite. The fact that you lose lightning is not a huge deal in my opinion. Your Stormscope will detect both cloud-to-ground and intra-cloud lightning. Comparing this to what you see on the Nexrad image with the visual outside of the window, you can usually tell whether this is just a heavy rain event versus a convective (thunderstorm) rain event. 2b. A Stormscope will show every strike it detects. As a result, you will be able to assess the relative strength of the storm and the location of the greatest activity. Mentally superimpose the cell mode Stormscope display with the XM weather Nexrad image and you have a pretty good indication of “don’t go there.” 3. You will also lose echo tops which seem to be a favorite element among pilots. Most pilots assume that echo tops equate to cloud tops and will allow them to know where the cloud tops are for the purposes of getting above icing. If the droplets or ice crystals in the clouds are not producing more than 18 dBZ returns, they will not show up on this product. This means that most of the time, supercooled clouds exist without any echo tops return. a. Ninety-nine percent of the time, echo tops will not represent the real tops of the clouds. Most of the time, the cloud tops will be a bit higher. Moreover, echo tops is a product of the WSR-88D radars (Nexrad) and has a resolution of 5000 feet based on the radar site elevation. As a result, no echo tops are reported below 5000 feet AGL. b. Echo tops is a product used by meteorologists to estimate the tops of thunderstorms. This helps meteorologists determine the relative strength of the storms (higher tops generally mean stronger updrafts and more severe storms). Echo tops are never used to determine the potential for icing. Who are the hardware manufacturers for XM Satellite Weather? Well, this one is easy. WxWorx is the manufacturer of the satellite receiver. If you want XM Satellite Weather, then you will be purchasing a WxWorx XM receiver (picture below-right).
However, this is just a satellite receiver. You still need to buy other elements such as a display device (PC or PDA), software, and GPS. There are several companies, including WxWorx, that are licensed to receive data off of this XM satellite receiver for processing and display purposes. That is, the WxWorx receiver has an output that can be read by proprietary software. You have the option of buying the WxWorx on Wings® with the premium mapping upgrade software. They offer no hardware bundled solutions. When buying this product you will receive the WxWorx receiver, WxWorx on Wings® software, DC power adapter, XM antenna and USB data connector. No display is included. The WxWorx on Wings® software will only run on a PC (they do not have a version that runs on a PDA). If you are already set on using a PC that has a processing speed of 800 MHz, then this will probably be your cheapest solution. The WxWorx software processes almost all of the data that comes over this link and displays it in a real clear fashion. Airgator manufactures NAVAirWx. Their XM weather solution runs both on a PDA and PC. Note that this software is different than the WxWorx on Wings® premium software. In fact, when you purchase NAVAirWx, you won't receive the WxWorx on Wings® software. Airgator offers many bundled solutions for both PDAs (iPAQ) as well as PCs such as the Fujitsu 5011 tablet and Sony U50/70. Prices for these bundles vary depending on the options chosen. Chesapeake Aviation Training is an authorized dealer for NAVAirWx. See http://airgator.com for more information on NAVAirWx. Control Vision manufactures Anywhere Wx and has both a Globalstar and XM solution that runs both on a PDA and PC. Chesapeake Aviation Training is an authorized dealer for this equipment. See http://controlvision.com for more information on Anywhere Wx. Others? Yes, there are other manufacturers of software and hardware that utilize the WxWorx receiver.
Wires, wires everywhere? About the only significant downside to a portable solution is the presence of wires. One of the key requirements for many of my customers has been a solution that minimizes wires. They don't want wires all over the cockpit or across their lap. But let’s get one thing clear; wires are only a problem if you make it a problem. Most wires can be easily buried or hidden. Many of the vendors of portable weather systems have done their best to minimize wires and have provided solutions that allow for a neat cockpit. You can have a service center to the work for you to make the "installation" as neat as possible, or you can take an afternoon and do it yourself with minimal trouble.
What about Bluetooth? Bluetooth is a great technology, will minimize wires, but has its shortcomings. Most Bluetooth solutions will raise the cost of the hardware nearly $250 or more. With Bluetooth you have two choices: 1. Bluetooth WxWorx receiver. You can communicate between your display device and the WxWorx receiver as long as the receiver is Bluetooth capable and the display device is Bluetooth capable. You still must power the WxWorx XM receiver, so the receiver cannot be completely wireless. Additionally, you probably will want to power the PDA or PC so you don’t lose your ability to display the weather if the battery dies. In this case at least one wire is necessary. In the end, you must either deal with batteries or wires. 2. Bluetooth GPS. This is probably the better of the two Bluetooth solutions and the least problematic. You can communicate from the display device to the GPS using Bluetooth. The GPS must be Bluetooth capable and the display device (PDA or PC) must also be Bluetooth capable. Again, the Bluetooth GPS must have a battery. Most of these are cell phone batteries and only last about 4-6 hours and must be recharged after each flight. Some Bluetooth GPS solutions also offer the ability to run off ship's power, but this involves an additional wire. If you really, really want to go Bluetooth, you better be a bit computer savvy.
Why not WSI? Several reasons drive me away from WSI. Even though the product is probably one of the best available, it is terribly overpriced. The suggested pricing is $3,495 plus installation for a non-certified solution. Oh, did I mention, you have to provide your own display? Add another $2000-$3000 for the display. At this price, you might as well go with the panel-mounted solution. WSI’s subscription service is $400 more a year to get the same weather data. Additionally, WSI requires an externally mounted antenna. And even though it is not certified, it can only be sold and installed by an FAA-approved station. See http://www.wsi.com/solutions/aviation/inflight/pricing.asp for WSI subscription pricing.
How about MAC users? Sorry to say that WxWorx on Wings®, NAVAir and Anywhere Wx do not run on the MAC operating system.
Do I have to buy another GPS? The short answer is no. However, as mentioned above, it seems a bit ridiculous to pay a couple thousand dollars for a weather system and not have it interfaced with a GPS. Placing yourself in relation to the weather is critical for strategic decision making. Many pilots already own a panel-mounted Garmin 430/530 or other portable GPS systems such as a Garmin 295 or 296. Can you use these as your GPS source? The answer is yes and no. I believe interfacing with these systems is totally possible, but not necessarily economically feasible. This has been accomplished by some pilots, but be careful about interfacing with TSO’d products; it may void the TSO if you add this interface. The last thing you want to do is turn your $10,000 plus panel-mounted IFR GPS into a VFR-only GPS. Personally, I believe the solution to interface with a panel-mounted GPS causes you to lose one of the key safeguards, namely, a battery powered backup GPS. If you were to lose all electrical or your GPS failed for some reason, having a portable GPS as a backup is a nice convenience. Even though the WxWorx receiver might not be powered during this failure, a backup GPS will continue to work powered by self-contained batteries or via the PC or PDA battery. Speaking of batteries, Husky makes a portable battery that has a convenience outlet for powering your system. It is large (about half the size of a car battery), but is made to be portable. This can be purchased at Home Depot for under $50. This will allow you to be completely independent of your aircraft electrical system.
Music and Weather? Can I also use the receiver to get XM music? Not necessarily. My understanding is that you can use the same antenna, but you still must have the XM radio receiver for music. Additionally, you cannot receive both weather and music at the same time.
What is my personal recommendation? Well if you’ve read this and are still distraught and you have no hope of making your own choice, let me make a recommendation. Airgator’s NAVAirWx bundle on the PDA is perhaps the cleanest most economic solution. You will get all the important weather elements at a very reasonable cost. You will still have to choose the display device (PDA or PC) if you would like the NAVAir solution.
Inevitably, once you have purchased your system, your next question will be “now that I have this data, how do I safely make use of it?” Having a background in meteorology and after flying for almost two years with these systems, I do offer strategic weather avoidance flight instruction. Call or e-mail for the details. Whatever solution you pick, I think you’ll be happy with it. If you have any questions, please don’t hesitate to call Scott at 410-379-5731 or e-mail me at contact@chesavtraining.com. I’d be happy to help you sort all of this out. Copyright © 2004-2005 Scott C. Dennstaedt. All rights reserved. |
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