Three Ground-Mapping GPS Handhelds

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It was April 1996 when Lowrance Electronics stood the aviation GPS market on its ear by introducing the AirMap, the first handheld aviation GPS with built-in ground-mapping capability. Now, pilots have three ground-mapping competitors to choose from: the AirMap 300, the Garmin GPSMAP-195, and the upgraded II Morrow Precedus. We've put all three through their paces on a long IFR X-C trip, and here's our in-depth evaluation.

ProductsNOTE: Since this comparison was originally written, Garmin introduced its lower-priced GPS III Pilot which also has ground-mapping capability. We've reviewed this unit in a separate article. Lowrance subsequently introduced its own lower-priced unit, the AirMap 100, which we've also reviewed separately.

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Change History

  • Lowrance introduces smaller AirMap 100 priced at $599, which we've reviewed in a separate article. (20-Apr-98)
  • Lowrance introduces 12-channel AirMap 300 priced at $799, and discontinues the original 5-channel AirMap. (19-Jan-98)
  • Garmin introduces another ground-mapping unit, the GPS III Pilot, which we've reviewed in a separate article. (01-Sep-97)
  • Lowrance drops the price of the AirMap and AirMap SE by $200. (15-Jun-97)
  • Lowrance AirMap software update v2.1 adds obstruction mapping, and the availability of an optional rechargable NiMH battery pack. (14-Apr-97)
  • II Morrow Precedus software update v6.1 adds new HSI screen, enhanced pan/zoom capabilities, and coastlines and political/territorial boundaries to the map display. (18-Nov-96)
  • Lowrance AirMap free software update v1.9 adds SUA look-ahead, VNAV, reduced keystrokes. (07-Oct-96)
  • Garmin says GPSMAP-195 order backlog remains at 6-to-8 weeks. (07-Oct-96)

Ground Mapping ... What's the Big Deal?

I must admit that when I first set eyes on the Lowrance AirMap in May, I was enormously skeptical about the merits of ground mapping in an aviation GPS handheld. Keep in mind that my flying is about 99% IFR, and that I'm not in the habit of paying attention to roads, rivers or railroad tracks, much less using them for navigation.

I'd flown with virtually every handheld GPS available up to that point, particularly the Garmin GPS-90 and the II Morrow Precedus, and also flown behind the Argus 5000 and 7000 panel-mount moving maps. It seemed to me that moving map displays were already too cluttered with airports, navaids and special-use airspace boundaries, especially in the complex and densely-packed airspace around Los Angeles and San Francisco where I often fly. So my first reaction was that I needed highways, waterways and other terrestrial features on my moving map about as badly as I needed a third control yoke or a quadricycle landing gear.

Lowrance AirMap But my first long IFR cross-country trip with the Lowrance AirMap changed my opinion. I found that the AirMap's display was not excessively cluttered or hard to read, despite the presence of ground mapping features. The AirMap's high-resolution display (with its 25,600 pixels capable of not only black and white but also gray) and its clever de-cluttering software (which automatically drops less-important map features as you zoom out to longer-range views) kept the display easy to interpret. And the ground features, although certainly not necessary for IFR X-C navigation, made the flight much more enjoyable:

"Ladies and gentlemen, we've just passed over the Sunshine VOR. To the left of the aircraft, you can see beautiful Lake of the Ozarks, one of Missouri's major recreational areas. The highway to our right is Interstate 44 which runs from Tulsa to St. Louis. The airport just on the other side of I-44 is Forney AAF which serves Ft. Leonard Wood..."

So while I still consider ground mapping to be a luxury rather than a necessity, I found it to be a very seductive luxury. The next time I flew with a moving map that lacked ground mapping, it somehow seemed to be crude and archaic. Luxuries are often like that: hard to give up once you get used to them.

Now there are three

Lowrance introduced the AirMap with an unprecedented advertising campaign in March 1996, showed the unit at Sun 'n Fun in April, and started production-quantity deliveries of customer units in May. Since then, they've been selling AirMaps as fast as they can make them.

Garmin GPSMAP-195 Garmin showed an early prototype of their ground-mapping handheld dubbed the GPSMAP-195 at Sun 'n Fun '96, but it became clear that Garmin's product development cycle was months behind Lowrance's and that they'd be lucky to have the 195 in production by Oshkosh in early August 1996. As it turned out, Garmin did deliver their first batch of production 195s to their dealers at Oshkosh. But it was a very small batch (about 100 units, we estimate) and sold out immediately, so most would-be buyers went home from Oshkosh empty-handed.

IIMorrow Apollo Precedus Not wanting to be left out, II Morrow released in late July 1996 an upgraded version of their Precedus handheld with mapping of highways and cities. The upgraded Precedus was in plentiful supply at Oshkosh. The ground-mapping upgrade required doubling the size of the unit's flash memory from 2 to 4 megabytes, but II Morrow offered a hardware retrofit for owners of earlier Precedus units, and in fact was performing the retrofit at their booth at Oshkosh on a while-you-wait basis!

Like thousands of other pilots, I checked out the new Garmin and the upgraded Precedus at Oshkosh '96. But there's no way of evaluating complex products like these in a quick in-booth demo. You've got to take them flying, preferably on a cross-country trip of significant length, to do a really meaningful review. I knew that my flight from Oshkosh back to California would be a perfect opportunity to put these units through their paces. So in the waning "dog days" of Oshkosh, with the crowds gone and the exhibitors impatiently waiting for the end of the show, I decided to see whether I could get my hands on all three competitors and conduct a real fly-off during my trip home.

I already had a loaner AirMap, and the nice folks at the Lowrance booth updated it to the latest software version (1.8 at that time). Tom Rogers of Avionics West had some of the upgraded Preceduses in stock and arranged for me to borrow one for the trip. The Garmin was the most difficult to come by because they were in such short supply and all customer units had long-since sold out. But Bob Cusick of Garmin came to my rescue by loaning me his personal demonstrator GPSMAP-195 for the flight home, after I solemnly promised him that I would FedEx it back to him the moment I got home. (Bob made me prick my finger and sign my name in blood.)

Mike Busch's Cessna T310R So Thursday morning, I launched westbound from Oshkosh in my Cessna T310R with three ground-mapping GPS handhelds aboard: an AirMap, a GPSMAP-195, and a Precedus. The flight to Santa Maria, California, was nearly 1,700 nautical miles, with a fuel stop at North Platte, Nebraska, and an R.O.N. at Grand Junction, Colorado. The route took me across the Great Plains, through the Denver Class B airspace, over the Rockies, through the maze of MOAs and Restricted Areas near Tonopah, Nevada (can you say "Area 51"?), across the 14,000-foot peaks of the Sierra Nevada, and across California's San Joachim valley to the Pacific coast. The entire trip was made under Instrument Flight Rules. Cruising altitude was 12,000 feet from Oshkosh to Denver, and FL180 (with a cannula up my nose) for most of the remainder of the trip. The weather was mostly clear and unrestricted, except for an area of airmass thunderstorms between Denver and Grand Junction that necessitated a good deal of off-airway deviation.

It was a marvelous flight, and a terrific opportunity to wring out the three GPS handhelds. Here's what I learned.


Hardware Comparison

IIMorrow Apollo Precedus Lowrance AirMap Garmin GPSMAP-195

Size and appearance

When you place the three handhelds side-by-side, the first thing you notice is a big difference in size. All three are about the same height: 7-1/2 inches, give or take an eighth. But the Precedus is much slimmer and more svelte than the other two. It looks rather like a cellular telephone with an oversized display, and in fact is only slightly bigger than my Mitsubishi Diamond-Tel cellphone or my ICOM IC-A22 comm transceiver. Like a cellphone, the Precedus fits comfortably in one hand and is easy to operate one-handed if you operate the keyboard with your thumb.

The AirMap and Garmin 195 are both half-again as wide as the Precedus (roughly 3 inches versus 2-1/8 inches). Both are uncomfortably large for one-handed operation; you find yourself either holding the radio in one hand and punching the keys with the index finger of the other hand, or else cradling the radio in both hands and operating the keys with both thumbs.

The Precedus and the AirMap are about the same thickness: 1-3/8 inches. The Garmin is substantially thicker at 2-1/8 inches, partly due to its unusual "sculptured" shape. It's big. About the size of a brick. A lot bigger than it looks in the advertising photos. Any bigger and you really couldn't call it a handheld. In fact, when I used the units in my motel room (for familiarization, pre-entering routes, and so forth), I almost always found myself placing the GPSMAP-195 on a desktop or tabletop and using it that way.

Appearance-wise, both the Precedus and the Garmin 195 project the look and feel of quality. The Precedus is packaged in a cast aluminum enclosure which gives it a solid feel and a surprisingly heavy weight considering its slim proportions. The Garmin's case is plastic, but its deeply sculptured shape and rubber inserts gives it a quality look. Surprisingly, the Garmin is only slightly heavier than the Precedus (1.4 lbs. versus 1.2 lbs.) despite its far bigger size.

By comparison, the AirMap plastic case gives it a somewhat cheaper-looking appearance. Of course, the AirMap is a good deal cheaper: $699 street price, versus about $995 for the Precedus and $1,199 for the GPSMAP-195. In actuality, however, the AirMap seems to be at least as rugged and well-built as the other two models. In fact, the AirMap's unusual flip-top antenna (which covers the display when folded to the closed position) means that you can toss the AirMap into your flight bag or briefcase without having to worry about scratching the display; with the Precedus or the Garmin 195, you have to slide the radio into its protective carrying case to keep the display from getting damaged.

Incidentally, the plastic case of the AirMap is welded shut, and can't be opened without destroying it. The Garmin's plastic case is screwed together with a gasket and nitrogen-filled. The aluminum case of the Precedus opens easily by removing a few screws, which made it possible for II Morrow to retrofit older units with the larger flash memory required for the mapping upgrade.

Displays: Precedus, AirMap 300, GPSMAP-195

Display

Perhaps the most significant hardware differences among the three units relate to their LCD displays. The Precedus, which was designed without ground mapping in mind, has a tall rectangular 1-3/8 by 2-7/8 inch display with 12,800-pixel resolution (80 by 160). With its intense blue color and large .45-millimeter pixel size, the Precedus display has the best contrast and readability of the three units over a wide range of lighting conditions and viewing angles, particularly in direct sunlight. But its lack of gray-scale capability severely limits its ability to portray ground mapping information in a legible fashion.

The Lowrance AirMap has a square 2-1/4 by 2-1/4 inch display. Its resolution is twice that of the Precedus: 25,600 pixels (160 by 160). Each .35-millimeter pixel has 3-level gray scale capability (black, white, or gray). This greatly enhances its ground mapping capability, since mapping features like lakes, rivers and ATC rings can be shown in gray without obscuring the airport and navaid icons and labels that are shown in black.

The importance of the AirMap's gray-scale display is particularly obvious when operating the AirMap in split-screen mode where the left half of the screen displays a moving map and the right half displays alphanumeric flight data. In this mode, the AirMap's map is 80 by 160 pixels precisely the same resolution as the Precedus and 22% smaller. Yet if a significant number of ground mapping features are visible, the AirMap's half-screen map is far more legible than the Precedus's full-screen map. Gray scale is the difference.

The Garmin GPSMAP-195 display goes even further. It has exactly the same width and pixel size as the AirMap, but is half again as tall: 2-1/4 by 3-3/8 inches and 38,400 pixels (160 by 240). Perhaps even more important, the Garmin's display supports 4-level gray scale (black, dark gray, light gray, white), giving the GPSMAP-195 an even better ability to display dense ground mapping information while still remaining legible.

The downside of these gray-scale displays is impaired contrast and a narrower viewing angle. I found both the AirMap and the Garmin 195 displays difficult to read clearly in direct sunlight. Usually, an adjustment to the display's contrast setting solved the problem, but when the lighting conditions changed, the contrast needed to be adjusted again. Although the blue-and-white display on the Precedus also has adjustable contrast, I never needed to fiddle with it.

All three units have backlit displays for night use. The Precedus and Garmin 195 both have white backlighting with three intensity levels (high, medium, low). The AirMap uses green backlighting with 16 intensity levels. All three are a real pleasure to use at night, particularly when operating off aircraft power so that the backlight can remain on continuously. When operating off battery power, all models extinguish their backlight after a time-out to maximize battery life.

Keypad

The differences in keypad design of the three models are not as obvious at first glance as the differences in their displays. But the importance of keypad layout and position becomes clear after you've flown with the units for awhile, particularly at night and in turbulence.

Precedus keypad The Precedus uses a simple 3-by-3 keypad layout, with nine large oval fingertip-sized keys located at the extreme bottom of the faceplate. Its large keys are wonderful for one-handed operation (when your thumb is the only finger available), and for use in turbulence. At night, they keys are magnificently backlit, appearing as glowing ovals with white legends. But nine keys don't seem to be quite enough. I wish II Morrow had added one more row of keys, like a telephone keypad. The absence of dedicated zoom-out/zoom-in keys and a "cancel" key are particularly noticeable.

GPSMAP-195 keypad The Garmin 195 has plenty of keys eight small chicklet-style function keys, plus a two-way zoom-in/zoom-out rocker key and a four-way left-right-up-down cursor control rocker essentially 14 separate keys. The keys are logically labeled and consistently employed, providing a straightforward user interface. The keys are black with white legends, and the legends are backlighted for night use.

But I found the Garmin's four-way cursor control keys to be more difficult to use than the four separate arrow keys used by the Precedus and AirMap. And sometimes I would have to press a key two or three times before the Garmin would recognize my keypad input; I couldn't tell whether this was a hardware or software problem, but I suspect the latter (so it's probably fixable).

(One possible explanation: if the Garmin's backlighting is activated intentionally or otherwise and times out, the first keypress of any key turns the backlighting on and doesn't perform its normal function.)

My biggest complaint about the Garmin keypad is its placement at the top of the unit, rather than at the bottom. The top-mounted keypad is fine when you're holding the 195 in both hands and operating the keys with your thumbs. But when the radio is in its yoke mount (where it is most of the time) and you're punching the keys with your index finger, it's hard to avoid covering up the display with your hand. Worse, the Garmin's top-mounted keypad dictated a bottom-mounted display, which I found to be too low for comfortable viewing during yoke-mounted operation. I often found myself having to tilt up the yoke mount to get a better view of the screen, which unfortunately causes the radio to obscure the instrument panel.

AirMap keypad The AirMap 300 keypad splits the difference between the Precedus and the Garmin. It has twelve keys, and is placed right in the middle of the unit, below the display and above the battery pack. This placement works well for both handheld and yoke-mounted operation. The keys are black with white legends, and at night the backlight makes them glow a luminous green. I only wish the keys were a bit larger there seems to be plenty of room in the AirMap's keypad layout for big, Precedus-sized keys.

Battery

Like the cellular phone that it resembles, the Precedus comes with a quick-change rechargeable ni-cad battery pack and a wall-transformer-type charger. In fact, the battery pack used by the Precedus is a standard NEC cellphone battery, so replacement battery packs are readily available anyplace that carries NEC phones. The standard battery is good for about 4 hours, but high-capacity packs offering 6 hours to a charge are also available.

The Garmin 195 comes with a battery case designed to hold six AA-size alkaline batteries, which Garmin claims will last "up to 10 hours" if backlighting is not used, although that figure seems a bit optimistic based on my tests. Garmin also offers an optional rechargeable ni-cad battery pack with an AC charger, which they claim will last up to 9 hours to a charge. But there is no provision for charging the pack in-flight while the GPS is being powered from the aircraft electrical system...a serious shortcoming in my view. In the event of an in-flight electrical failure, the Garmin's battery might easily start out with less than a full charge. Consequently, the ni-cad option on the Garmin 195 might not be such a good idea unless you also carry an alkaline battery pack loaded with six fresh AA's as a backup.

The AirMap 300 has the most flexible power system of all. It comes standard with two battery packs: an alkaline pack that takes six AA-size batteries, and a rechargeable NiMH (nickel metal hydride) pack with a built-in smart charger. The NiMH battery is immune from the "memory effect" that plagues ni-cads, can be recharged in-flight while the GPS is in use, assuring that it'll be fully charged in the event of an electrical failure. (An AC charger is not included, but is available for an extra $30.) Battery life varies from 4 to 10 hours, depending on what update rate is configured. The AirMap can also be run off aircraft power with the battery pack removed, reducing the size of the unit by nearly half and making it extremely compact.

Opinions are divided concerning whether alkalines or rechargeables (ni-cad or NiMH) are the better power source for a handheld GPS. Many pilots prefer alkalines because they have excellent shelf-life, provide about twice the running time of ni-cads, and are available at any drugstore or supermarket. I prefer rechargeables because I normally fly with the GPS plugged into aircraft power, so battery operation is only an issue for me during ground use or in the event of an in-flight electrical failure and in either case, 4 hours is plenty. Good quality AA alkalines (I prefer Duracells) cost a dollar or more apiece, so a new set of alkalines for the AirMap or Garmin 195 costs at least six bucks.

Antenna

All three models use a flat patch-style GPS antenna. The Precedus and Garmin 195 use an antenna mounted in the "nose" of the radio, while the AirMap uses a unique "flip-top" antenna hinged to the top of the unit and serving also as a protective cover for the display when the AirMap is not in use.

For in-flight use (at least in my airplane), it proved essential to use a remote-mounted antenna located on the glareshield or suction-cup-mounted to the windshield. All three models allow for this, but in different ways. Both the Precedus and the AirMap allow their attached antennas to be removed from the radio and mounted in a suitable location, and both include a coaxial cable for hooking the remote-mounted antenna to the radio. The antenna on the Precedus slides off and back on very easily. The flip-top AirMap antenna used to be rather a pain to detach and reattach, but Lowrance redesigned the antenna attachment scheme in the spring of 1997, and owners of earlier models can retrofit their thumbwheel-type units easily. The Garmin 195 offers the best solution of all: a separate remote antenna and cable that can be left permanently in the airplane (assuming you own one), and plugs into an antenna jack on the radio. All three models come with a suction-cup mount for remote-mounting the antenna to the windshield.

Yoke Mount

Yoke mounts also come standard with all three models. I like the one that comes with the Precedus best by far: it's small, sleek and elegant (like the radio itself) and something you don't mind leaving in the airplane permanently (again, assuming you own one). The Precedus snaps in and out of its yoke mount easily.

The Garmin yoke mount is much bigger, heavier, and more complex (as is the radio). A knob on the mount is used to lock and release the radio. The cigarette lighter power cord screws onto a couple of little ears on the yoke mount and automatically engages the power connector on the 195 when it is locked into the mount. I found, however, that the power connector doesn't make reliable contact unless you're very careful about how you insert the radio into the yoke mount. This isn't a big problem once you're aware of it, but it definitely can bite the novice user. The Garmin does display an icon at the bottom of the screen to show which power source is being used, and it's a good habit to double-check it.

The AirMap yoke mount is my least favorite of the three. Not only is it big and heavy, but it relies on Velcro rather than clips to attach the AirMap to the mount. I found that the Velcro simply isn't strong enough (or perhaps not enough of it is used) to hold the AirMap securely to the mount, assuming you fly with one of the battery packs in place. It's not hard to dislodge the radio inadvertently, and I'm concerned that a yoke-mounted AirMap might become a projectile in severe turbulence (although it did hang on okay when I flew through some moderate bumps). With the battery detached and running solely on aircraft power, the AirMap becomes small and light enough that the Velcro mount is fine.

Software and database updates

All three models are designed so that both their databases and operating software can be updated in the field. The Precedus and Garmin 195 are both updated by hooking the radio to an IBM-compatible PC using a special data cable and uploading the update from the PC. The updates are distributed on copy-protected diskettes. Although this approach works fine, we have two beefs with it. First, both II Morrow and Garmin classify the data cable and PC update kit as extra-cost options ($100 for the Precedus, unknown for the Garmin); we think they should be included as standard equipment. Second, unless you have an IBM-compatible PC, you're out of luck. (Macintosh owners might get away with using a PC emulator like Soft-PC, but I haven't been able to confirm this.)

The AirMap uses a totally different scheme, one that I like a lot better. Database and software updates are distributed on tiny cartridges that plug into the back of the radio. When a new database update arrives, you simply pull out the old cartridge, plug in the new one, and send the old one back to Lowrance in the special mailer that comes with the update. Software updates are slightly different: you plug the software cartridge into the AirMap and turn it on, whereupon it automatically loads the new software into its internal flash memory; then you unplug the software cartridge and mail it back to Lowrance. No PC or cable is required. Furthermore, Lowrance charges substantially less for its Jeppesen database updates than the competition ($75 for the AirMap versus $125 for the Garmin).


Software Comparison

All three models are loaded with features, most of which are implemented in software. And all three allow their software to be updated by the user. II Morrow introduced the Precedus at Oshkosh '95, and has been continuously refining and enhancing its software since then, and owners of even the earliest Precedus units have been able to benefit from the improvements. Lowrance and Garmin have both released a number of improved software refinements, and the enhancements are likely to continue.

Menus

All three units use menu-driven user interfaces, but there are significant differences. The Precedus has a single 13-entry function menu that appears whenever the user presses the "menu" key. You select a menu function by moving the cursor to the desired item with the up/down arrow keys, then pressing the "enter" key. The top menu item is "Return to Nav" which takes you back to the navigation/map pages. The other 12 menu items call up specialized pages that permit you to configure the various system and mapping functions, initialize the GPS position and clock, start and stop timers, perform E6B functions, access checklists, and so forth. For the most part, the Precedus user interface is very straightforward and easy to learn and use.

The AirMap also uses a single function menu that appears when the user presses the "menu" key. The menu contains about 16 entries (sometimes one or two more or less, depending on what feature are active) but only 6 of them are visible in the menu window at a time the rest much be reached by scrolling as you move the cursor through the menu using the up/down arrow keys. I found the inability to see the entire menu at once makes the AirMap a bit more difficult to learn and use, although it's not a major obstacle. Another AirMap oddity: to execute a menu item, you hit the right-arrow key (rather than the "enter" key as on other models). This feels strange at first, but I got used to it quickly.

The Garmin's menu system works a little differently. Pressing the "menu" key brings up one of several alternative menus, depending on what nav page is being displayed when you press the key. If you press "menu" while looking at the map page, for example, a map-option menu pops up; if you do the same thing while looking at the active route page, a route-option menu pops up instead; and so forth. Regardless of which menu pops up, pressing "menu" a second time brings up the main menu. I found this "context-sensitive" menu approach to be harder to get used to at first, but it saves a few keystrokes in the hands of an experienced Garmin user.

Because the Garmin has so many specialized menus, the menus tend to have relatively few items, and they are displayed in a larger, easier-to-read font than the Precedus or AirMap. Menu items that are inapplicable in the present context are "grayed out", similar to Windows or Macintosh menus a nice touch.

Navigation Pages

As it comes pre-set from the factory, the Precedus displays seven navigation pages:

  • A full-screen map page
  • A split-screen page with a 2/3-screen map plus four alphanumeric nav-info fields
  • Two alphanumeric nav pages, each with up to twelve nav-info field
  • A messages page
  • A GPS status page
  • A route page

The Precedus nav pages are highly user-customizable. You can specify between one and four alphanumeric nav pages, each containing up to twelve fields that you can select from a palette of 34 different nav-info items. You can also customize the four fields on the split-screen page in the same fashion.

When the Precedus is in navigation mode (as it is most of the time), you cycle through these various nav pages by pressing the up- and down-arrow keys. The left- and right-arrow keys are used to zoom the map pages in and out. In flight, I find myself toggling frequently back and forth between the split-screen map page (which I've configured to show distance-to-waypoint, groundspeed, bearing and track) and one of the alphanumeric nav pages (to see CDI, time-to-station and time-to-destination, among other items). This isn't particularly difficult to do, but I've often wished for more than four nav-info fields on the Precedus split-screen page. (II Morrow's software whizzes could have accomplished this easily, simply by using a smaller font for the nav-info. But then I'm sure they'd have gotten hate mail from hundreds of farsighted pilots who need the big, easy-to-read fonts!)

The Garmin GPSMAP-195 uses a very similar design as the Precedus, with a few important differences. It has only one map page and one alphanumeric nav-info page, but that's enough because its screen is so big that it can get three times as much information on a page as the Precedus can. The Garmin does offer an interesting "HSI" page that has no parallel on the Precedus. This makes a total of six nav pages in all, which you can cycle through by pressing the "page" key. (The "quit" key cycles through them backwards.) Map zooming is accomplished with the dedicated zoom-in/zoom-out rocker key. This leaves the four-way cursor control rocker free for slewing the cursor around the map (discussed below).

Like the Precedus, the Garmin allows user customization of all the nav-info fields from a lengthy palette of choices. It also allows its single map page to be customized: you can select a full-screen map or a variety of split-screen options with 2, 4, 6 or 8 nav-info fields, or with 0, 2, 4 or 6 fields plus a CDI display. I settled on a split-screen configuration with 6 nav-info fields plus a CDI display. That proved sufficient to display almost all of the nav-data I needed to fly with, and still left enough screen space for a very respectable (AirMap-sized) moving map. With this configuration, I found that I almost never needed to toggle to another nav page except when using some exotic feature such as VNAV.

The AirMap works a bit differently. It offers a tremendous variety of different nav page layouts 21 different pages if I counted correctly most of them user-customizable. In addition to the usual map, alphanumeric, and split-screen pages, the AirMap offers a variety of dual-map screen layouts, where each map is individually configurable and zoomable. Just to cite one example: you can bring up a display where the left half of the screen is an ordinary moving map, the upper-right-hand quadrant is a second map zoomed in tightly on the destination airport, and the lower-right-hand quadrant displays four nav-data items (e.g., distance, groundspeed, bearing and track).

There are two downsides to the AirMap's plethora of pages. First, there are too many of them to simply cycle through sequentially like the Precedus and Garmin do. To change nav pages on the AirMap, you press the "mode" key to bring up a menu of pages, then use the arrow keys to specify the page you want, and finally press the "exit" key to make the menu go away. Definitely more cumbersome than simply cycling through six or seven pages with a single key. Second, customizing the pages on the AirMap is more difficult and less intuitive than on the other two units.

Ground Mapping

As I said at the outset of this article, I consider ground mapping to be a nice feature of a handheld GPS, not an essential one. I certainly wouldn't choose which one to buy strictly on the basis of its ground mapping capability alone. But if ground mapping is your top priority, then the Garmin 195 has to be your GPS of choice.

Taking full advantage of its big, 4-level gray scale display, the Garmin software engineers have managed to create a moving map that looks astonishingly like a sectional chart. Highways, rivers and lakes look very much like they would on a chart. Railroad tracks are distinguishable from roads by their little tick marks. Major metropolitan areas are shown in light gray and labeled; smaller cities and towns appear in close-up zooms. Airports appear as dark circles with a white slash through them, and the slash is even oriented in the direction of the longest runway. VORs are depicted using the familiar hexagonal VOR symbol (sans compass rose), and even indicate whether the navaid has DME or not. The attention to detail is remarkable.

My hat is off to Garmin for doing such a first-class job with the mapping software. About the only way they could make the GPSMAP-195 display look more like a sectional would be to install a color display. Maybe that'll be the big news at Oshkosh '97...

The AirMap pioneered ground mapping in aviation handhelds, and does a very credible job. The AirMap's display, while only 2/3 the size of the Garmin's, is still plenty big and capable for the task. But the AirMap's marine heritage is obvious. Its standard background map depicts rivers, lakes and coastlines in faithful detail, but highways are sometimes mislocated by as much as a mile, and railroad tracks don't appear at all. Airports and navaids appear precisely where they belong, but no attempt is made to depict them using standard aviation symbology. In short, I found the AirMap's ground mapping capability to be quite good, but the Garmin's to be breathtaking.

However, starting with the version 2.1 update, the Lowrance has added a unique new capability to the AirMap: an obstacle database, and mapping of obstacles. Antenna towers and the like now show up on the map, complete with their elevations (you can specify MSL or AGL). This is a very useful safety feature, and one that the competition is sure to notice.

The Precedus comes in a very distant third in the ground mapping department. Its relatively small, non-gray-scale display was never designed for such a task. It's simply impossible to depict very much ground mapping information on a display like that without it becoming too cluttered to read. The Precedus ground mapping capability is limited to highways and city names no rivers, or lakes are depicted, nor railroad tracks. In the version 6.1 software upgrade, the Precedus added coastlines and territorial/political boundaries to the map.

This is not to say that II Morrow's highway mapping upgrade to the Precedus isn't a worthwhile one. It's a nice addition, and it's a real tribute to II Morrow that they could (and did) make such an upgrade available to all existing Precedus owners. But limitations of the Precedus display hardware make it impossible for this unit to compete with units like the AirMap and Garmin 195 that were designed from the outset for ground mapping.

All three models let you specify whether you want the map display to be oriented north-up, track-up, or course-up. On the AirMap's dual-map pages, you can set the orientations of the two maps independently. I normally use track-up orientation in-flight, as I imagine most pilots do.

In track-up or course-up mode, both the AirMap and the Garmin include a "north indicator" to give you a general idea of which way the map is oriented. (The Precedus doesn't.) Both the Precedus and the Garmin display the little airplane symbol that represents your present position about 3/4 of the way down the screen, so the map view focuses on where you're going rather than where you've been. The AirMap puts the airplane symbol in the center of the screen (again reflecting the marine heritage of the design), but Lowrance told me they're changing this in an upcoming software update.

Zoom and Auto-Zoom

The AirMap and Garmin 195 allow you to zoom the map in or out over an enormous range of scales. The AirMap zoom goes from screen widths of 0.1 NM to 4,000 NM, and the Garmin goes from 0.1 NM to 3,000 NM. The maximum zoom-out lets you see the entire North American continent at once the maximum zoom-in would let you taxi to the correct tiedown in zero-zero conditions (if it weren't for the DOD's Selective Availability program that intentionally degrades GPS accuracy). Both units have dedicated zoom-in/zoom-out keys on the keypad to control this function.

The Precedus zoom goes from 0.1 NM to 250 NM. The lack of extreme zoom-out is inconsequential for in-flight use (where ranges of 5 to 150 NM are typically used). But it is occasionally useful during flight planning on the ground; e.g., to answer questions like "does my route from Cincinnati to Tulsa pass through Arkansas?" Not a big issue. The Precedus doesn't have dedicated zoom keys, and uses the left- and right-arrow keys instead.

When you zoom in or out on any of these models, there's a delay while the microprocessor constructs the new map. And because I tend to zoom in and out a lot in flight, I consider the length of this delay to be a significant issue. And in this area, the AirMap wins hands-down. The AirMap almost never takes more than one second to display the new map after a zoom-in or zoom-out request, while both the Garmin and the Precedus frequently take four or five seconds. That may not seem very long, but I find it very irritating. I'm not sure why the AirMap is so much faster than the other two it might have a faster microprocessor or more efficient software, I can't tell. But whatever magic Lowrance is using to make the AirMap perform so fast, I think that Garmin and II Morrow should pay attention.

All three models also offer an "auto-zoom" feature that lets the software automatically adjust the zoom range to display your current route segment, zooming in automatically as you near the fix, and zooming out once you've passed the fix to let you see the next route segment. This is an extremely useful feature and I find myself using it most of the time when in-flight. When auto-zoom is active, the speed of the AirMap's map processing (and the slowness of the Garmin's and Precedus's) are especially obvious because the zoom range is changing so frequently (particularly as you approach a fix). The Garmin is especially distracting in this regard, constantly popping up its "Loading..." message at the worst possible time.

Garmin explained to me why the -195's map redrawing speed is so much slower than the AirMap's. It turns out that the -195 software generates not just one but five screens worth of map each time you zoom: the visible screen, plus a screen's worth of unseen map data to the left, right, above and below the visible screen! This is needed to support the Garmin's "smooth-scroll" panning feature (described below). Coupled with the fact that the Garmin's screen is 50% larger than the AirMap's, and that its map is considerably more detailed, it's no wonder that its map redrawing speed is so slow. Nevertheless, understanding the reason doesn't make it any less annoying.

Another area where the Garmin software needs work occurs as you approach your destination airport with auto-zoom enabled. With all three models, the airport's runway configuration becomes visible as you zoom in past a certain point. With the AirMap in auto-zoom mode, this usually seems to happen at about 4 miles from the airport. The Precedus is about the same. But with the Garmin, it seemed as if you couldn't "see" the runways until you were nearly in the traffic pattern. (Garmin tells me the runway layout is displayed at the 12-mile scale and below, but I sure couldn't see it.)

Regional Mapping Cartridges

In addition to the built-in worldwide base map that comes with the AirMap and the Garmin 195, both radios have a provision for regional mapping cartridges to be plugged in to provide additional ground mapping detail. The AirMap cartridges are available now; the Garmin's are not, but they're planned for sometime in the future. (The Precedus has no cartridge slot.)

Lowrance offers cartridges for 64 different regions that cover the conterminous U.S. I obtained the cartridge for Southern California and evaluated it in my AirMap. The cartridge does indeed offer lots of additional ground-mapping detail, and it also seems to fix the positional errors in highway depiction the roads in the cartridge appear to be spot-on.

However, the regional mapping cartridges for the AirMap seem to be useful primarily for terrestrial and marine use, but not particularly helpful for aviation. This is because the mapping features from the cartridge only seem to show up when the map is zoomed in below the 10-mile range. At ranges of 10 miles and up, the display seems to be the same whether or not the cartridge is plugged in. Since zoom ranges below 10 miles are seldom used in-flight (except in the final few minutes of a flight as you approach the traffic pattern), the cartridges don't help very much.

Furthermore, for a long cross-country trip (like my flight from Oshkosh to California), you'd need a godawful number of cartridges to cover the route (probably a couple of dozen), and you'd be too busy changing cartridges to pay much attention to the display (or your flying). To make matters even more ridiculous, the AirMap manual stresses that the unit should be turned off before you insert or remove a cartridge. So even if you were inclined to carry a sackful of cartridges and change them in-flight as you fly from one regional coverage to the next, the GPS would have to reacquire the satellites after each cartridge change.

Bottom line: the regional cartridges may help you drive home from the airport, but they won't do much for you in the airplane.

Garmin wasn't talking about how soon their regional cartridges would be available, how big the coverage would be for each cartridge, how close you'd have to zoom in to see the additional details. They did tell me that the radio doesn't have to be powered down to change cartridges. Availability of the cartridges uncertain, but I don't much care the base map built into the Garmin 195 offers plenty of ground mapping detail for my needs.

De-Cluttering

One of the design challenges in any moving map display particularly one that does ground mapping is how to avoid displaying so much information that the screen becomes illegible. All three units do a decent job of de-cluttering, although frankly I think they could do better.

The de-cluttering function of the AirMap is completely automatic and non-customizable. In some 7,000 NM of cross-country flying with the AirMap in all sorts of areas and conditions, I've found that it works surprisingly well. But once in a while, when flying over sparsely-populated areas, the screen gets rather sparse and I wish I could ask the AirMap to display some more detail. And occasionally when flying in especially complex and densely-packed airspace (like Southern California), the screen gets a bit cluttered and I wish I could drop out a bit of detail. Unfortunately, there's no way to do this with the AirMap.

Both the Precedus and the Garmin 195 do permit the user to customize the de-cluttering algorithm. But doing so involves adjusting a zillion different parameters. At what minimum zoom range do you want to eliminate state highways? Federal highways? Interstates? City names? Airport identifiers? VOR identifiers? Intersections? Class D airspace rings? And so forth. Get the picture? It's so complicated to customize the de-cluttering algorithm that in practice, I'm never inclined to fool with it.

In my humble opinion, what all three units need is a simple way for the user to say "show me a little bit more detail" or "show me a little bit less" or "go back to the default." I hope the crack software engineers at Garmin, Lowrance and II Morrow are listening.

Cursor/Pan Mode

All three models have the capability of slewing a cursor around the map. This is used for two purposes: to point to something on the map (usually an airport, fix, or airspace boundary) in order to get more information about it or to navigate there, or to "pan" the map window by slewing the cursor beyond the edge of the map. This is an important and often-used feature, and each model implements it somewhat differently.

The AirMap has a particularly nice cursor mode. To activate it, you simply press any of the four arrow keys while any map page is being displayed. Crosshairs appear, and you can easily and precisely slew them to any location on the map with the arrow keys. If you slew the cursor close to any edge of the map, the map is redrawn (after a one-second delay) centered on the cursor position. Once you've placed the cursor where you want it, you can ask the AirMap to:

  • Navigate a great-circle route to the cursor position
  • Drop an icon onto the map at the cursor position for future reference
  • Create a user-defined waypoint at the cursor position
  • Search for the nearest airports, VORs, NDBs, etc. relative to the cursor position
  • Identify any special-use airspace that contains the cursor position
  • Zoom the map in on the cursor position to have a closer look

To leave cursor mode, you press the "exit" key. The map resumes its previous zoom level (or auto-zoom, if that was in effect) and re-centers on your present position.

The Garmin 195's cursor mode operates in a very similar fashion to the AirMap (so much so that you'd swear Garmin copied it), but there are a few differences worth noting. I found positioning the cursor more difficult with the Garmin than the AirMap's. The Garmin uses a sort of "bullseye" symbol as its cursor (instead of crosshairs), and I had some difficulty with this cursor symbol obscuring the map items that I was trying to point at.

In addition, I'd often find that while slewing the cursor with the Garmin's four-way rocker, the cursor would sometimes continue to "coast" for a short time after I released the key, overshooting my desired location. This never happens on the AirMap, and may be another indication that the Garmin's microprocessor is slower and less responsive than the AirMap's. (Garmin says this "cursor coasting" problem is known and being addressed.)

When you slew the Garmin's cursor off the edge of the map window, it behaves differently than the AirMap. If you slew the cursor only a short distance beyond the edge of the map window, the whole map smooth-scrolls as necessary to keep the cursor on-screen...very nice! But if you slew the cursor significantly further, the radio puts up that loathesome "Loading" message for 4 or 5 seconds while it recalculates five screenfuls of map data...ugh!

An outstanding feature of the Garmin's cursor mode is that when you touch any map feature with the cursor, up pops a little label telling you what it is. If you touch an airport symbol, it's identifier appears. If you touch a highway, its route number pops up. And if you touch a river or railroad track, it actually pops up a little label that says "Russian River" or "Union Pacific RR" or whatever. Now that's really slick!

But surprisingly, if you press the Garmin's "nrst" key while in cursor mode, it displays a list of nearest airports to your present position, not the cursor position. I like the AirMap's way of doing this a lot better. Another nasty glitch in the Garmin's cursor mode: if you slew the cursor somewhere and then zoom-in for a closer look, when you cancel cursor mode (by pressing "quit") the map doesn't return to its previous zoom level. Very annoying. I figured this was an oversight in the software, but Garmin seems to think it's a feature...go figure!

The Precedus calls its cursor mode "pan mode" and you enter and leave it by pressing the "enter" key while the full-screen map page is on the display. Once in pan mode, a little plus-sign appears on the map, and you can slew it around with the arrow keys. If you touch any airport or navaid with the cursor, its identifier is highlighted and you can get additional information about it by pressing the "info" key. If you touch any special-use-airspace boundary with the cursor, it intensifies you can then press the "info" key and see information about that SUA region (name, altitude limits, controlling agency, etc.). The SUA information page even includes a perspective drawing of the SUA area which you can rotate and tilt, but I consider this mostly a gimmick and not particularly useful some software engineer at II Morrow must have had too much time on his hands!

If you slew the cursor beyond the edge of the map window, the Precedus locks up for 4 or 5 seconds while it's constructing a new map display. The same thing happens whenever you enter or leave pan mode. I find these delays very annoying. Also, the lack of dedicated zoom-in/zoom-out keys on the Precedus makes it very difficult to zoom the display while in pan mode. Prior to software version 5.1, it was literally impossible; in later versions, there's a way to zoom, but it involves moving the cursor to a particular location on the screen and is extremely awkward. Finally, in the 6.1 software update, the II Morrow engineers fixed the pan/zoom mode so it's actually reasonable to use..

Route Mode

All three models offer a route mode which enable you to set up multi-waypoint routes and have the GPS automatically sequence from segment to segment as you fly. All allow you to store up to 20 such routes in memory, and to fly the routes either forwards or backward. Since I fly mostly IFR and largely on airways, this is a feature that I use a great deal. All three units do a good job here, but there are a few differences.

All three units have a route editor that lets you create and modify routes. I found the route editor in the Precedus to be the easiest to master, and the one in the Garmin to be the most confusing (at least at first). My loaner GPSMAP-195 didn't have a manual with it, but I've talked to a couple of 195 owners who had difficulty figuring out the route editor even after reading the manual. I think Garmin needs to make a few software tweaks in this area.

When flying a route and approaching an intermediate fix, it's nice to know the magnetic course of the next leg before actually reaching the fix so you can lead the turn the faster the airplane, the more important this is. The Precedus and AirMap both offer a "turn anticipation" feature when route mode is active. I like the way the Precedus does this best: at a user-programmable distance from the fix, it displays an arrival alert which includes the identifier, course, and distance to the succeeding fix. The AirMap also has an arrival alert with a user-programmable lead distance, but its alert message doesn't include the next fix or course instead, it simply sequences to the next leg at the lead point, making the next leg info available on the normal nav pages. The Garmin 195 has an arrival alert, but it lacks any turn-anticipation information (other than requiring you to switch to the route page and look it up); hopefully, Garmin will emulate the Precedus' approach in a future software update.

Approaches

One of the niftiest capabilities of the Precedus is its "approach monitor" feature. This works in conjunction with the route mode, and lets you automatically set up an approach at the destination airport of the route. You can choose from any published GPS approach for the destination airport, or you can select a do-it-yourself approach that starts at a fix 4 miles out on the extended centerline of any runway. While no handheld GPS is certified for instrument approaches (and probably never will be), I find this capability to be extremely useful for maintaining positional awareness while flying VFR at night or in hazy conditions.

The Garmin 195 provides a similar capability, but it's limited to published GPS approaches and lacks the runway centerline extension feature. This limits its utility considerably compared to the Precedus. Lots of airports have no published GPS approaches at all, but all have runway centerlines. (Garmin indicated that they intentionally avoided emulating the Precedus' runway-extension feature because Garmin considered it potentially dangerous.)

Unfortunately, the AirMap offers no approach capability at all, but does offer centerline extensions.

Airport Information

All three models offer airport information such as field elevation, runway diagrams, runway lengths, and frequencies for ATIS, tower, ground, clearance, AWOS, UNICOM, and CTAF. All do a good job here, but the Precedus is the easiest to use (it has a dedicated "info" key) and offers the most complete information, including approach and departure control frequencies and even a sunrise/sunset calculator.

Nearest Waypoint Search

All three models offer a nearest waypoint search, but the one implemented by the Precedus is the most comprehensive. The Precedus displays up to 40 nearest items in each of the following categories: airports, VORs, NDBs, intersections, special-use airspace areas, cities, and user-defined waypoints. What's more, it somehow manages to come up them virtually instantaneously.

The AirMap search displays up to 40 nearest waypoints in each of the following categories: airports, VORs, NDBs, intersections and user-defined waypoints. The AirMap takes several seconds to come up with each list. A very useful feature unique to the AirMap is the ability to perform a nearest-waypoint search centered on any desired cursor position (rather than just from the present GPS position).

The Garmin 195 search displays the 9 nearest airports to the present GPS position. Pressing the menu key at this point allows you to access nearest waypoints of other categories.

User-Defined Waypoints

All models allow you to define hundreds of user-defined waypoints. But surprisingly, neither the AirMap nor the Garmin let you define a waypoint as a radial and distance from a VOR or other known fix only the Precedus lets you do this. And the Precedus doesn't allow you to define a waypoint based on cursor position both the AirMap and Garmin do.

The inability to define a waypoint based on radial and distance is a particular problem for instrument pilots like me, because ATC frequently specifies routings in that fashion. Even my seven-year-old loran knows how to do this, so it's amazing that two bleeding-edge GPS's don't. Hopefully, Garmin and Lowrance will see fit to add this capability in a future software release. (Garmin says they're planning this in the next release.)

HSI Page

The Garmin 195 and AirMap both include an interesting "HSI" page that is particularly useful for intercepting airways and radials, flying holding patterns, and providing backup guidance during instrument approaches.

The Garmin HSI page looks precisely like a real horizontal situation indicator instrument, complete with compass rose, course arrow, heading bug, lubber line, and rectilinear CDI needle. If you're used to flying a real HSI, you'll adapt to the Garmin's electronic version instantly.

The AirMap's HSI page only vaguely resembles a real HSI. It's more like peering through a window in the belly of the airplane and looking down on a "road" that portrays the desired route. The centerline is visible, as are the edges of the route (which represent full-scale CDI deflection) and the aircraft's actual track history. You can also watch route fixes as they pass by below. It's useful, but not nearly as nice as the Garmin.

The Precedus now has an HSI page that is very similar to the one on the Garmin 195.

Vertical Navigation

The Garmin 195 and AirMap both offer a vertical navigation feature that helps you plan letdowns from altitude. To use it, you bring up a setup page and specify what altitude you want to descend to (generally pattern altitude or initial approach altitude), how far from the airport you want to reach that altitude (4 miles seems to be a good figure), and how rapidly you want to descend (I used 800 feet per minute).

The Garmin monitors your GPS altitude (which is not terribly accurate, but is good enough for this purpose) and alerts you when it thinks you need to start down. You can then switch to the HSI page, on which a "glideslope" needle appears to guide you down. (Garmin prefers to avoid the word "glideslope" for fear some yo-yo will try to shoot a precision approach with it...and in fact, the software shuts off the VNAV indicator 500 feet above the target altitude.) There's also a numeric readout that continuously shows you the descent rate necessary to get to the preprogrammed location and altitude.

I found this feature particularly useful during the flight home from Oshkosh, because it involved two descents from FL180 that needed to be started quite far in advance. Although I've become pretty adept at calculating such descents in my head, I liked the Garmin's VNAV capability and would probably use it regularly if I owned a 195.

Lowrance added VNAV capability to the AirMap in the version 1.9 software upgrade, but it offers only a digital readout of the target altitude, rather than the "simulated glideslope needle" display of the Garmin.

The Precedus displays GPS altitude, but doesn't have any VNAV function.

GPS Initialization

When you first fire up any of the units out of the box, you're instructed to give the GPS receiver a rough idea of where it's located so it knows what satellites to look for and can acquire position reasonably quickly. You're supposed to do the same thing anytime the unit is relocated by more than about 300 miles while turned off. If you don't do this, the receivers can use a "cold start" procedure to figure out where they are, but this can take as much as 10 or 15 minutes.

Initializing the Precedus is a bit awkward, because you have to specify the initial position in terms of latitude and longitude. If you don't have an approach plate handy, you can use the GPS itself to look up a nearby airport, write down the lat/lon, and then enter those number onto the GPS setup page. But this seems ridiculous. Why doesn't the software simply let you enter an airport identifier on the initialization page and skip the lat/lon nonsense?

The Garmin 195 has an even niftier way of handling this problem. When you select GPS initialization function, the unit displays a map of North America at an extremely wide scale (3000 NM). All you need to do is to slew a little arrow to the general vicinity of your present position, and the GPS has what it needs to perform a rapid acquisition of satellites. A very nice touch, I think.

The AirMap allows initializing in both ways: by pointing at the map (like the -195), or by entering a lat/lon (like the Precedus).


GPS Receiver Performance

The original AirMap had a 5-channel GPS receiver, but Lowrance upgraded to a 12-channel engine when it introduced the AirMap 300 in January 1998. The Precedus has an 8-channel receiver and the Garmin has a 12-channel receiver. How much difference does this make, if any?

All three units performed very well in actual flight conditions, using the supplied antenna remotely mounted on the glareshield or suction-cupped to the windshield. The 5-channel AirMap and Precedus have lost position only rarely in all the time I've flown with them, and usually reaquired position within seconds. I've never seen the 12-channel units (Garmin or AirMap 300) lose position fix.

To make things more difficult, I ran some tests with the three units side-by-side under marginal reception conditions (on a picnic table in my backyard, under a big oak tree that seriously degraded reception) and timed how long they took to acquire a fix. I also forced losses of position (by covering the antenna with my hand) and then timed how long they took to reacquire.

The Garmin consistently acquired its fix most quickly after power-up. It always acquired within 45 seconds, and usually within 20 seconds. The 12-channel AirMap 300 was about the same. The older 5-channel AirMap was a bit slower, typically taking 50 seconds or so to acquire a fix. The Precedus was slowest, taking 90 seconds and sometimes even more to acquire. It's not clear that these differences are really significant, however. If you power up any of these units at engine start, all will have locked on long before you have time to taxi out and do a runup.

In-flight loss of position is more significant. Here again, the 12-channel units (Garmin and AirMap 300) really shined it was very difficult to get it to lose position in my (admittedly unscientific) tests. The Precedus was slightly less resistant to losing position, and the 5-channel AirMap was the least resistant. These results correlate directly with the number of receiver channels, and that makes sense when you think about it. A GPS receiver needs to be tracking four satellites in order to calculate a 3D fix, or three satellites to calculate a 2D fix. The more satellites in addition to that minimum of three or four that the receiver can track, the less likely it is that it will lose position if reception of one or more satellites are lost. The 5-channel AirMap tracks only two "extra" satellites beyond the minimum of three required, while the 8-channel Precedus tracks five "extras" and the 12-channel Garmin and AirMap 300 can simultaneously track every visible satellite in the sky. But despite these worst-case test results, I must emphasize that I've flown a lot with the 5-channel AirMap and found it to do a great job under actual flight conditions.

After an artificially-induced loss of signal, all three receivers did an excellent job of reacquiring their position quickly. The 12-channel units (Garmin and AirMap 300) usually reacquired in 10 seconds, the 5-channel AirMap in 20 seconds, and the Precedus in 30 seconds. Once again, these tests were done under unusually poor signal conditions (under the tree).


Summary and Recommendations

All three of these models are truly outstanding, but all of them have some significant weak points, and all have a room for improvement. Fortunately, many of the needed improvements are in software, and all three units allow for software updates in the field. So over the coming months, we can expect these radios to get better and better as the manufacturers continue to release incremental software enhancements.

Garmin GPSMAP-195 The Garmin GPSMAP-195 is extremely impressive, and at $1,199 street price it should be. Its ground mapping capability is easily the best on the market, thanks to its extraordinary 4-level gray scale display plus exceptional attention to detail in its mapping software. It also has many other innovative features, and a red-hot 12-channel GPS receiver.

My biggest gripes with the new Garmin are its brick-like size (it barely qualifies as a handheld in my book), its high-mounted keypad and low-mounted display (bass-ackwards for yoke-mounted use to my way of thinking), and its painfully slow response to zoom and pan requests. They've made some improvements in this last area in a recent software update. I also don't care for the fact that the Garmin's optional ni-cad battery pack cannot be recharged in-flight.

IIMorrow Apollo PrecedusThe II Morrow Precedus is a first-rate, highly refined GPS that does almost everything superbly except ground mapping. Its sleek, slim cellphone-like styling, high-contrast display and large oval keys make it a real pleasure to use while handheld or yoke-mounted. I really like its approach monitor feature, its easy-to-use interface, and its rechargeable cellphone battery.

The principal deficiency of the Precedus is its lack of gray scale display capability for ground mapping. Its pan/zoom capability used to be very cumbersome, but this has been fixed in the v6.1 software release.

At $995 street price, the Precedus is a decent buy.

Lowrance AirMap Priced a whopping $400 less than the Garmin 195 and $200 less than the Precedus, the Lowrance AirMap 300 at $799 easily offers the "best bang for the buck" of any unit tested. Although the AirMap's ground mapping isn't quite as attractive as the Garmin, it's still darn good. The AirMap also has a better cursor mode, much faster zooms and pans than the competition, and some novel features such as dual-map pages. It's upgraded 12-channel GPS receiver is every bit as good as Garmin's. I also like its system for database and software updates (via cartridge rather than PC download).

Weakest points of the AirMap are its Velcro yoke mount (which I consider adequate only if you operate the unit without the battery pack installed), cheaper-looking plastic case, lack of approach monitor capability, and a user interface that is not quite as easy to learn or use as the other units. Lowrance has gradually been improving the user-friendliness of this unit (as well as its feature set) through a succession of software upgrades.

Recommendations

If you want the best ground mapping available, the Garmin GPSMAP-195 is your obvious choice. If you're on a budget, the Lowrance AirMap 300 is an excellent radio at an unbeatable price. And if you're not mesmerized by ground mapping and prefer a more compact unit, the Precedus is still a superb GPS and II Morrow keeps making it better and better. It's hard to go wrong with any of these models they all do a great job.


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