Private homepage – Hans-Georg Michna

Global Positioning System

HANS-GEORG MICHNA

Global Positioning System Information and Data for Germany and East Africa

Contents

• Nature Reserve Mapping Project
• GPS
• Data
• For Pilots: GPS Emergency Approaches
• Garmin GPS 12 Test Review
• Garmin III Pilot
• Garmin eMap
• Garmin GPSMAP 76C
• Virtual Geocache on the Equator
• Send Mail

Links

• See the private homepage for information on travelling in east Africa.
• See http://members.aol.com/gpspage/ for some Kilimanjaro trekking waypoints.
• See the software page for a GPS route file converter program for Marco Polo Großer Reiseplaner and the TOP series German topographical maps.
• A far more versatile, but still free conversion program is Top50Trans.
• Currently you can download corfu.exe (3.3 MB), a high-resolution map of the Greek island of Corfu, calibrated and ready for use in OziExplorer (requires registered version, available from www.oziexplorer.com).
• Read the story and download the routes for a 5 hour Bavarian mountain hike to the Baumgartenschneid.

Nature Reserve Mapping Project

History

This project began as the Nature Reserve Waypoint Project and asked contributors to send in waypoints of track or trail junctions. However, nobody came forward, so the project existed only in the form of two of my own waypoint collections.

However, meanwhile a technical detail changed. Newer GPS receives have a much larger track memory, and so there is a new opportunity to revive this project under a new name with some decisive advantages over the old one:

1. It is now even less work, namely almost no work at all, to collect the data. Just record the track while you drive or walk. But load the track from this page first, to benefit from the information.
2. The result is much more useful, because it does not only record arbitrarily chosen junctions but entire tracks or trails.
3. Most GPS receivers can be set to overwrite the oldest track information when their track memory overflows. This provides us with automatic ageing, so obsolete information is automatically discarded.

The New Project

So please join a new project to gather nature reserve GPS information. This is a collaborative project that aims at achieving a maximum of usefulness with a minimum of effort. The idea is that travellers record tracks. The names of all contributors will be mentioned in a list here, provided anybody volunteers.

You can take part only if you have one of those newer GPS receivers with 10,000 track points, like the following.

• Garmin GPSMAP 60C
• Garmin GPSMAP 60CS
• Garmin GPSMAP 76C
• Garmin GPSMAP 76CS
• Garmin GPSMAP 96C
• The x versions of the above GPS receivers
• Any other newer Garmin GPS receiver with at least 10,000 track points

Please send me an email if you know another popular GPS receiver with 10,000 or more track points or when you need the tracks in a different file format.

Currently present are 4 nature reserves, Lake Nakuru National Park, Samburu Game Reserve, and two large parts of Masai Mara, all in Kenya, east Africa.

If you have Google Earth installed, you can open the Amboseli 2005 example file to have a look at the GPS tracks.

Procedure

1. Download the track file.
2. Delete the entire track memory of your GPS receiver.
3. Use a recent version of MapSource (download from www.garmin.com) to upload the tracks into your Garmin GPS receiver or, if you have a different type of GPS receiver, discuss the technical side with me.
4. Set your GPS device up suitably, i.e. set the number of displayed trackpoints to the maximum (for example, 10000 on a Garmin GPSMAP 76C). Set the track recording method and the track display to Auto and Wrap When Full and the track point density to Normal, Less Often, or Least Often (for larger areas). Less Often may be the better choice because it allows a longer total track than Normal. Use Least Often for large areas like Masai Mara.
5. Drive. Enjoy.
6. Before you leave the area, please contribute by reading the tracks from your GPS receiver and emailing them to me. Do not drive too far from the area before you do that, because that could overwrite the oldest relevant tracks.

I will replace the oldest ones here with your fresh ones and mention your name in a list of contributors.

Problems

1. No contributors. Please contribute to alleviate this problem. Meanwhile I'll keep feeding it with my own tracks.
2. I don't know yet how the various GPS receivers deal with the track segment names, but I hope it will just work. I'll test this as soon as I get to it.
3. Different GPS receivers. I don't know how the different track memory space of different receivers will work in the framework of this project. We'll see.

GPS

GPS (Global Positioning System) is one of the technical marvels of our time. See www.gpsinformation.net for the best source of general GPS information plus a very good collection of Web links and see www.trimble.com/gps/ for an excellent illustrated and animated explanation of how GPS works. More info can be found at the following sites.

GPS Tutorials

www.edu-observatory.org/gps/tutorials.html
www.trimble.com/gps/index.html

NAVSTAR GPS User Equipment Introduction

www.navcen.uscg.gov/pubs/gps/gpsuser/gpsuser.pdf

Also see

www.gpsy.com/gpsinfo/
http://home-2.worldonline.nl/~samsvl/
www.best.com/~williams/avform.html
http://vancouver-webpages.com/peter/

Introduction

www.edu-observatory.org/gps/tutorials.html
www.Colorado.EDU/geography/gcraft/notes/notes.html
www.groenveld.de/pub/article.php?artid=148 (Very good, detailed article on the GPS fundamentals in German language)

Books and Technical Documents

www.navcen.uscg.gov/gps/geninfo/default.htm
www.nima.mil/GandG/pubs.html
www.navtechgps.com/
www.edu-observatory.org/gps/gps_books.html

Waypoints, Maps & GIS

www.edu-observatory.org/maps/waypoints.html
www.edu-observatory.org/maps/maps.html
www.edu-observatory.org/gis/gis.html
www.edu-observatory.org/maps/utm.html

On May 1st, 2000, the US made a surprise move and switched off the dreaded Selective Availability (SA) distortion of the GPS sattelite signals. This instantly makes all existing GPS receivers much more precise without requiring any changes or upgrades to the devices. With good sattelite reception we now get a position error of less than 15 m with a probability of 95%. The altitude error remains bigger than the position error by a factor of roughly 1.5 but has now become usable for many more purposes for which it was too imprecise in the days of SA. There are no plans to switch SA back on.

If you get a GPS and plan to use the unit extensively, buy three sets of rechargeable high capacity (1,600 mAh or more) NiMH accumulators and a really good quick charger. If you can, build yourself a computer connection cable (search the Web for a source of the special Garmin plug and the schematic) or bite your tongue and shell out for the expensive one available from Garmin. Save the money for the Garmin mounts and for the even more expensive cigarette lighter power cable. Instead buy a mobile phone holder with a suction cup that you can attach to the windshield of a car or aeroplane. This has worked very well for me through thousands of miles in a small jeep over gruesome tracks that almost shook the car apart, and also in light aeroplanes. If you can find it, buy a RAM windshield holder that matches your GPS.

Data

In the descriptions and sometimes in the names of the waypoints you may occasionally find the following single or two letter abbreviations.

When both direction and graphical depiction are present, the graphical depiction always comes last.

Some of the approximately 350 east African waypoints may be inaccurate. Please do not rely on them too heavily and please try to verify or remeasure them and email me your results.

In addition, some of the east African waypoints are taken with a lower numeric accuracy or from unreliable sources. Many of the airport waypoints are up to one mile off, for various reasons. I found a few that were some 5 miles off until I corrected them. Sometimes the waypoint designated an airfield but was really positioned in a nearby town or lodge. In one case (Mt. Kenya Safari Club) an airfield waypoint turned out not to be an airfield at all but the mountain lodge itself. (Of course I have already corrected these, but some others will certainly still be inaccurate.)

Below you can download GPS-Waypoints for Germany and for East Africa with emphasis on Kenya and the surrounding areas. Most waypoints are intended for flying, and most of them are airports or airfields.

The Germany information was valid in the year 2000 and has been superficially checked, but not fully updated in 2002. There may have been a few changes meanwhile, so check at least those airports that you plan to use before you fly.

The east African waypoints have last been used, checked and enhanced in 2004. They contain some useful driving waypoints and routes (see description further down). The files contain a lot of airports farther from Kenya, covering the area E 25° to 45° and S 15° to N 15°.

Specific information for the east Africa waypoints

If your GPS receiver can only store 500 waypoints, you can easily create a reduced version, for example without the waypoints south of south 7°, i.e. south of the Dar es Salaam latitude. Load the GDB file into MapSource or the TXT file into Excel or some other editor, select all waypoints south of S7°, and delete them.

MapSource is a Garmin program that can exchange waypoint, route, and map data with Garmin GPS receivers. A new version is required. If you have an older version, download the free upgrade from www.garmin.com and install it, otherwise you may not be able to read the files you can download here.

You can use Excel to load the text files and save them in different formats, like CSV. You can also use an editor, like the simple Windows editor, after that to replace commas with semicolons or vice versa for different national versions of Excel, because the data doesn't contain any commas or semicolons---these are only used as separators.

The following table defines the use of the symbols on the Garmin GPS devices. You can use these to delete waypoints by symbol on a Garmin GPS device or in the computer and thus separate the flying from the driving waypoints.

Special reporting points are available for the Nairobi Wilson northeast and southeast access lanes and some other places.

Northeast access lane inbound: NAI-N1 – NAI-N2 – NAIWIL
Southeast access lane inbound: NAI-S1 – NAI-S2 – NAIWIL
Prohibited area north of Wilson airport: NAI-P3
Points on the control zone boundary: NAI-N, NAI-NW, NAI-W
South corner of area 2 (if not using the southeast access lane): NAI-S

Mandatory reporting points for some German airports are similarly arranged, with the digit 1 always designating the outer reporting point of an access route. Occasionally, when an access route is curved and you have to turn at a point that is not a reporting point, I have inserted a waypoint at the turning point. Example: The Hannover departure route “Lima” uses the waypoints HAN – HAN-E2 – HAN-LX – HAN-L.

HAN is Hannover airport. HAN-E2 is a mandatory reporting point. Flying outbound, at HAN-LX you have to turn right (south) towards the next mandatory reporting point HAN-L, but HAN-LX itself is not a reporting point, only a course change point. Thus HAN has the + symbol I use for airports, HAN-E2 (like HAN-E1) and HAN-L have the symbol I use for mandatory reporting points, but HAN-LX has the symbol I use for other flying navigation points.

Here is the Nairobi Control Zone:

Nairobi Control Zone

The following table explains the east African driving routes. The routes beginning in Nairobi all use a shortcut from the western part of the city. If you start on Uhuru Highway in the center of the city instead, then you can simply drive north on Uhuru Highway through Westlands and continue straight in the direction to Naivasha and Nakuru until you meet the route. All routes use the turnoff to the old road down into the Rift Valley to Mai Mahiu, because this road is currently in a good state and more beautiful than the new road to Naivasha.

For Pilots: GPS Emergency Approach

Here are some thoughts on an emergency that can happen in a light aircraft when flying VFR and have a handheld GPS on board. Assume, for example, that you are flying VFR on top and your single engine fails. Another case in which a GPS can help might occur if you get trapped in clouds, but there you still have your engine at least, which makes it easier. Still the GPS can help.

In IFR-equipped aeroplanes you have very nice things like a big screen GPS, a flight director, etc. In a single engine plane with just a handheld non-aviation GPS you have much less, but with some ingenuity it should still be possible to fly some kind of workable approach.

Obviously, if you have a moment of time, you should declare an emergency immediately and keep telling the controller what you’re up to.

Assuming that you loaded at least all airfields near your planned route into the GPS receiver, you can quickly find the nearest airfield.

For simplicity the calculations and examples assume a (slow) gliding speed of 60 kt, because at this speed the numbers are very simple. If you really fly 70 kt, don’t worry. All our calculations cannot exactly account for your particular case anyway, so we are calculating roughly correctly and assume a sink rate of 800 ft/min. All heights are above ground, so with the common QNH altimeter setting you always have to deduct the height of the airfield from your altimeter reading.

Use the suitable special features of your GPS. For example, the Garmin GPSMAP 60/76/96 C/CS series has display fields for sink rate and sink rate to destination. Have these activated before you even take off. If you clicked on your desired emergency destination, then on Go To, and see that your required sink rate to destination is lower than your actual sink rate, you know you won't make it, so you have to do something.

Assuming that you don’t have much spare distance to soar and therefore have to try to make it to the airport without flying around aimlessly, but you still want to fly at least a short, straight final approach, one method could be this:

1. Airfield—Point your aircraft straight towards the nearest airfield and reduce your speed to no more and not much less than the maximum gliding distance speed. Don’t worry too much about the runway direction now. It is better to land anywhere, in any direction inside the airport, like diagonally on the runway or on the grass, than out in the bush.
2. Engine—Try to restart the engine. If this fails and if you have some more miles to fly, try to stop the windmilling propeller by setting it to maximum RPM if it is a constant speed propeller on a piston engine, then raising the nose and flying very slowly, but only for a short moment. Don’t lose too much height though. Don’t overdo it. Give up when you come too close to stalling speed, which is the end of green line minus some correction if you’re light. A windmilling propeller is an unwanted brake. If you still have the time, use the starter to rotate the propeller into a horizontal orientation to make propeller ground contact during the landing less likely. Switch the ignition off. 2003-10-06 – J. Carlos Goncalves sent the following hint: "If you have a constant speed propeller use coarse pitch—low RPM—to try to stop it. It did work, and seemed to be the only way, on the North American Harvard T-6 and Dornier DO-27. Otherwise it was very difficult to stop the propeller." Thanks, Carlos.
3. GPS Goto—Enter a Goto command for the airfield waypoint into your GPS, so you see the distance. Be sure to know the quickest method for that, which may involve pointing at the waypoint on the map display. On some GPS devices like the Garmin GPS 12 it may be enough to select the waypoint. And of course you have set your GPS to nautical miles before you even started, right?
4. Gyro—Quickly check and adjust your gyro compass.
5. Height—Calculate whether you have more than 800 ft of height above ground for each mile still to fly. Example: If you are 2 nm from the field and 2,000 ft above ground, you have 400 ft to spare (2,000 ft - 2 x 800 ft) and can use these to maneuver towards the actual runway direction and threshold. Remember though that you have only 2 minutes for this maneuver. When you have only 1,600 ft altitude above ground left, then you have to turn towards the airfield, otherwise you may not make it. 1 nm from the field is about the latest to fly any significant maneuvers. Any closer and you can only make some small, gentle turns, because you cannot fly any significant turns so short before the unavoidable landing. As usual, it’s the extra, spare height that counts. If you have much less than 800 ft per nm of distance, for example less than 500 ft per nm, you will most likely not reach the airfield. It may still be a good idea to fly towards it, because the area around it may be flatter than other areas.
6. Radio—Declare an emergency. Explain the situation briefly, but flying and navigating have priority.
7. Runway direction—Compare your flying direction against the runway direction. If the difference is much more than 90°, you’ll have to fly past the airfield and turn. You need extra height for that maneuver. Consider using the opposite runway direction.
8. Approach fix—Now you have to calculate a little. You want to know where the runway threshold and a suitable final approach fix is. Look at the directional gyro and find the runway direction. For example, if the runway is 24, look for the figure 24 on the gyro. That’s the far end of the runway. On the opposite side is your runway threshold. Change your flying direction a little towards that side. Look at the GPS map screen and imagine the runway on the waypoint in the same orientation it has on the directional gyro. 1 nm from the waypoint on the threshold side is your final approach fix, some 800 to 1,000 ft above the ground, depending, of course, on the wind as well. Look at the zoom factor, determine the (invisible) point on the GPS screen, and steer towards that approach fix.
9. Height—Check your height. Do you have height to spare? Depending on whether the runway direction is favorable or not, you need extra height for the maneuvering to your final approach. In the worst case, when you have to land from the opposite side, you need about 1,600 ft extra height from overflying the field to touchdown, because that’s 2 extra nm. Determine whether you have enough spare height for that. If you don’t, forget about the runway direction, fly straight to the airfield, and land, even if the direction is totally wrong.
10. Shortcut or detour—When you have flown some of the distance, like half, to your final approach fix, check your height again. If you have more height than you need, move the final approach fix out to, say, 2 nm from the field. In any case, turn further away from the direction to the field to lengthen your flight and lose height. If you're low, turn towards the field and move your final approach fix closer to the field, but if you’d have to move it closer than 1 nm, it’s better to give up on the approach fix altogether and aim for reaching the field in a gentle curve (or straight, if you find yourself too low).
11. Descent—When you reach your final approach fix, check your height again. If you have any more than 800 ft per nm still to fly, lower the flaps half way and trim. Check again quickly. If you’re still staying too high, don’t hesitate to lower the flaps all the way and trim again. Keep checking your height and, of course, speed. If you’re still high, sideslip. If even this is not enough, push the nose down a bit and fly to the side and back. If you’re 2,000 ft too high, fly a 360° rate 1 turn which should get you down almost 2,000 ft, but be very careful to end the turn when you’re flying towards the airfield again, which you can see on your GPS map display. If, however, you are too low, i.e. less than 800 ft per nm still to fly, immediately bring the flaps back up all the way while letting the nose drop a bit to gather the required speed, then fly directly towards the airfield at the optimal, longest distance gliding speed.

During all this quick maneuvering never forget to keep your speed at the proper approach speed. You don’t want a stall-spin accident now. And keep in mind that 1,000 ft too high is pretty bad, but still better than 10 ft too low.

If your directional estimate turns out to be inaccurate, you will notice after turning in that your flight direction is not exactly equal to the runway direction. If you have some extra height to lose, turn again to compensate for the discrepancy and fly an S-like course that ends again in the runway direction. Of course, as soon as you’re no longer perfectly sure that you can make it to the airfield, immediately turn in and fly directly towards the airfield.

You should never need this procedure when your engine is still running, but in the unlikely case that you do have to make something like an instrument approach on a handheld GPS, lower the required heights above ground to some 600 ft per nm of distance, which corresponds roughly to a 6° glide angle.

That’s a rough plan, but you may find that the mere thinking about it will prepare you for such an occasion. Let’s hope it will never happen, but be prepared anyway.

Garmin GPS 12

First of all I would like to state that I like the Garmin GPS 12 a lot and will most likely have bought the very same device again as you read this, after giving my first one away as a gift to a flying club in Africa.

While I will concentrate on things that don’t work as one would expect in the following report, I still think that at the price of around $150 this device is very hard to beat.

I tested the device in an aeroplane in Germany and on more than 4,000 km attached to the windshield of a Suzuki Sierra Jeep in Kenya, East Africa, in extreme conditions of heat, dust and shaking. A lot of the distance was driven on gravel and stony roads in dry areas of Kenya. I don’t think that anybody would use the device in conditions that are more difficult than these. During and after the test the device worked without a hitch, except for the points described below. Essentially the device kept working extremely well and withstood these most adverse conditions perfectly.

I bought a $20 mobile phone windshield holder that attaches to the windshield by means of a suction cup. This little helper proved excellent in both aeroplanes and cars, and I cannot remember a single case when the device lost track, except in cities between high buildings. (No, I don’t fly that way, this happened only in a car <grin>.)

Strengths

(just the most important ones, in brief)

Very good reception, up to 12 satellites at once.

Sensible, ingenious user interface, however still bent towards technically oriented users, requires a considerable amount of learning

Moving map display of user waypoints, routes and covered track

Particular dislay pages for particular purposes, very well tailored to the purpose

Very low price

Weaknesses

Does Not Show All Waypoints

The map shows only the 9 waypoints closest to your current position plus those on the active route. If you pan to a different area, you do not see the waypoints in that area, which makes trip planning very difficult.

I believe that this is by far the most severe shortcoming of the Garmin GPS 12.

Workaround: There is a way to go to another place in simulator mode, but this is very awkward. You have set the device to simulator mode, then travel in simulator mode (use a very high speed to save time) or enter the coordinates of the desired position by hand.

ETA Creep

A whole range of problems exists in connection with ETA (Estimated Time of Arrival), usually leading to the ETA being extremely optimistic and being changed to later times continuously while you travel.

The most severe of these problems arises when you bypass a waypoint of your route. The Garmin GPS 12 then makes certain assumptions which are rather unintelligent. When you begin to bypass a waypoint in some distance, the device assumes that your speed component towards the waypoint will remain constant, which in reality would happen only if you moved towards the waypoint in a converging spiral.

This might be bearable, but the device also makes the assumption that you will approach all further waypoints also in the same way, even if you are already moving directly towards the next waypoint. This is utterly nonsensical and renders the entire ETA prediction questionable.

Workaround: Take the ETA as a very optimistic estimate, especially when closing in on a waypoint.

Confusing Rename Function

When you change some characteristic of a waypoint, the waypoint is changed in memory. However, this does not work for the name of the waypoint, which initially confuses every Garmin GPS 12 user. What inevitably happens several times to the newcomer is that he attempts to change the name of a waypoint and instead creates a new waypoint at his current position.

There is a separate, unintuitive rename function.

Workaround: Learn to use Rename and bite your tongue every time you forget to use it.

Buttons Hang

Sometimes some of the rubber buttons hang. When you press them, then release them, they stick and remain pressed.

This went away again on its own on my device. I don’t know how frequently this occurs.

Workaround: Push the hanging button sideways, such that it pops out again. Hope that some dust and dirt and wear will resolve the problem over time.

Switch Off When Shaken

Sometimes the device switches itself off when shaken in a car (attached to windshield). This happens up to three times after a battery change, then the device stabilizes. After some shaking apparently the battery contacts get scratched enough to yield good contact.

Workaround: Wipe the battery contacts clean and keep switching it on again. Fasten some soft material like foam rubber or sponge under the holder if it knocks against the dashboard.

Random Walk

The device very often detects random walk movement when there is actually no movement. This renders statistics like trip time useless.

I think the device should instead register movement only when it actually leaves the random walk range.

Workaround: Don’t trust the statistics. Apply some corrections. Add a bit to the average speed, subtract a bit from trip time, etc.

Conclusion

Altogether, especially considering the very low price of the Garmin GPS 12, I consider the device eminently usable ond of high value. It can be a life saver.

Garmin III Pilot

I also had the opportunity to play with a Garmin III Pilot for one day, which I used to compare the two devices and find out whether the 4 times more expensive device adds considerably more value. Again, the test was done in East Africa, reflecting the point that you probably need the device more in an unfamiliar area than at home.

The Garmin III Pilot has an airport, city, water and road database and was the old world variant that covers Africa, not the North American version.

The result of the test was very disappointing, mainly because the airport database lacks 95% of the required information, and the remaining 5% contain many severe errors, like even big, important airfields missing (Arusha) or the busiest airport of all Africa outside South Africa, Wilson Airport Nairobi, being shown with one runway instead of the two runways it has had for half a century.

An additional problem is that database information often is not displayed until you zoom in to an improbable zoom factor. In the limited time I didn’t find out whether this can be changed by the user, partly because there are many settings, and these do not always seem to be arranged well.

Yet another problem is that after I loaded the missing database information into the Garmin III Pilot as user waypoints, the few actually existing database waypoints were overlaid by the corresponding user waypoints, leaving no way to select them on the map or even know that they are there at all.

Altogether I consider the Garmin III Pilot severely deficient to the degree of actually being dangerous and recommend not to use it, at least not outside your backyard. I also think that the offer of an airport database borders on fraud if almost all existing airports, even quite important ones with big hard-surface runways or lots of traffic, are actually not in the database.

For those looking for an inexpensive handheld GPS receiver this is good news. It means you can save a bundle by buying the much cheaper Garmin GPS 12 and save yourself a lot of trouble at the same time.

I have not looked at the usefulness of the Garmin GPS 12 XL or the Garmin GPS 12 CX. It is possible that either of these offers additional useful information, but on the other hand I guess that a city database may not be overly useful, as it is usually not too difficult to find the nearest city without a GPS receiver. And these devices are already much more expensive than the Garmin GPS 12.

I received this message in response to the above review:

Date: Tue, 04 Jan 2000 21:19:18 -0500
From: Colin Rasmussen <colin@pombe.usask.ca>
Organization: University of Saskatchewan
To: Hans-Georg Michna <hans-georg7@michna.com>
Subject: GPS Pilot III

I was surprised to read your negative review of this GPS on your webpage. I have one, and have found it to be very good. While it lacks some features of the Garmin 195, it is significantly less expensive.

Just to let you know, you can change the display to show various items at different zoom levels. Depending on what is important to you, you can have the things you navigate with available at the zoom level you typically use.

As far as the database goes, I live in Canada and it is excellent. On occasion I find some of the data re: ATC frequencies and procedures different, but this is rare.

Colin Rasmussen

Garmin eMap

I now have an eMap as well, which I use for driving, walking, and flying. It is not perfect for flying but I still prefer it over the GPS 12, because the larger, higher resolution screen of the eMap outweighs its lack of certain functions. One obvious deficiency is the lack of the highway page of the Garmin GPS 12. This means that it is more difficult to fly precisely along a straight line. A workaround is to zoom in for precise straight line navigation along a preprogrammed route and zoom out for the normal map view. Autozoom is confusing, and I recommend to switch it off for flying.

Hint: For flying switch off all maps except the base map and WorldMap, because they clutter your screen and cause unwanted road lock. An easy way to do that is to press Menu twice, select MapSource Info, press Menu again and select Show Base Map. Show Base Map also shows WorldMap if loaded. Use Show All to reactivate MetroGuide and other detailed maps.

Garmin GPSMAP 76C

Short Description

I have a Garmin GPSMAP 76C, and am very impressed with this handheld device. This device is functionally equivalent and has the same firmware as the Garmin GPSMAP 60C, Garmin GPSMAP 60CS, Garmin GPSMAP 76CS and possibly the Garmin GPSMAP 96C.

In 2006 newer versions have come to market, which have an additional lower case x appended to their names, like the Garmin GPSMAP 60Cx (now my recommendation), Garmin GPSMAP 76Cx, Garmin GPSMAP 60CSx, and Garmin GPSMAP 76CSx. These newer devices use a highly sensitive Sirf chip set and have removable memory modules with up to 512 MB of map memory, possibly more in the future, when higher capacity modules become available.

I had the Americas version (the one that has the Americas base map) bought in America, because it's cheaper, and have the relevant parts of the European City Select v6 map loaded, plus some parts of Garmin's WorldMap for the rest of Europe and parts of Africa.

Compared to the eMap with a 32 MB memory module that I used before, the 115 MB map memory is much better (though I wouldn't mind ten times as much).

The display is a pleasant surprise and contributes a lot to the long battery life (up to 30 hours). It is smaller than the eMap's, though the device is quite a bit bigger, but it has color and more pixels. It works and looks very good in external light like daylight, sunlight, and has backlighting for the night.

The essential function over and above the eMap is the auto-routing, also called turn-by-turn routing, which works excellently. The firmware design is impressive, the screens look almost like Windows and work similarly, with dialog boxes, etc.

The GPS receiver is even quicker and apparently more sensitive than the one of the eMap. It can use WAAS, EGNOS, etc., for 2 to 3 m (7 to 10 ft) accuracy.

The routing is very good, although people always seem to find a few places in which they would drive differently. It knows turn-off lanes and directs you into them before actually reaching the turn-off itself. It knows about one-way streets, etc., but that's more a feature of the very good and apparently very new maps. The device only has to support these features, which it does.

The 76C is marketed as a marine device. It floats and sustains some submersion in water. I preferred it over its very similar, but different-looking brother, the 60C, because the latter has only 56 MB map memory, but with the newer x versions this reason no longer exists, so the 60Cx could now be the prime choice.

The display screens and the data fields are extremely customizable. You can change the number of fields and the content of each display field to your liking. Pilots will welcome display fields like vertical speed and required vertical speed to destination, which should work when the altitude of the destination is known. Haven't tried that yet. Anyway, when your engine fails and you see that the required vertical speed is lower than the actual one, you know you have to do something.

I recommend it to everybody who wants an outdoor GPS that doubles as a car navigator, or vice versa, and who doesn't want to spend two to four times the price on a device permanently mounted in the car. In the car I use it with a suction cup holder that attaches to the windshield.

Garmin's page for the 60Cx is at http://www.garmin.com/products/gpsmap60cx/.

Get a bigger memory module

The 60Cx and its brethren come with a 64 MB memory module installed, which is far too small for my taste, so get a bigger one, preferably the biggest you can get.

I hope that 1 GB modules are becoming available some time in 2006, and I hope that the device will be compatible with them. Make sure you don't buy a module, only to find that the device is not compatible!

Get the Latest Firmware

Regularly check for and download the latest firmware from Garmin. They often upgrade the firmware, and it's usually worth getting the latest, because of bugs removed and features refined or added.

On www.garmin.com click on Software Downloads, select your device, download the latest firmware, and load it into your device, using fresh batteries.

Calculate a Better Route

The device has a memory. When you calculate a route, it uses your previous route, even if it led elsewhere, and tries to improve it. Due to the limited memory and processor resources, it cannot find the optimal route in the limited time it tries to keep. First of all, set it to Best Route, with the following commands: MENU, MENU, Setup, ENTER, Routing, ENTER, Follow Road Options (rocker switch up), ENTER, Calculation Method, ENTER, Best Route, ENTER. Now press PAGE, PAGE, to get out of the menu again.

Try to recalculate several times. In one of my examples the device regularly found a shorter route in the fourth recalculation.

Another method is to calculate an entirely different route, perhaps an extremely short one in the wrong direction. This makes the device forget the previous route. Then calculate the one again that you originally wanted. It is my impression that these methods help particularly when calculating the shortest route.

Choose a Different Starting Point

If you want to calculate a route that doesn't begin where you currently are, use the following method.

First switch the device into demo mode. To do that, go to the satellite page, press MENU, Use Without GPS, ENTER.

Still on the satellite page, press MENU, New Location, ENTER, Use Map, ENTER.

Zoom in and move the pointer to your desired start position. Put your starting point to the side of the road you're starting from, not in the middle of the road. Press ENTER.

Now let the device route to the desired destination.

Reroute Around Road Blockages

I tried a few things on the Garmin GPSMAP 76C with the European City Select v6 loaded (should work equally on the 60C, 60CS, 76CS, 96, and 96C) and found a pleasant surprise, which could, however, not been reproduced with the US City Select map. Seems to work only in Europe. Please drop me a mail if you find out about other maps.

The problem is this. You're driving on a freeway, guided by your friendly GPS, when you suddenly learn about a traffic jam in front of you.

So you drive off the freeway at the next opportunity. However, the GPS doesn't understand your intentions and only proposes that you turn back onto the freeway. Of course you don't know the area and have no clue where to turn. Exactly when you need your GPS the most, it fails you.

It seems though that the designers were cleverer than I first thought. They only failed to communicate this to us and they didn't quite make the function obvious. What I found is that the following function doesn't mean what it says:

MENU, MENU, Setup, ENTER, Routing, ENTER, Follow Road Options... (rocker switch up), ENTER, Avoid Highways (rocker switch up 2 times), ENTER to set the check mark.

PAGE 4 times to get back to the map page, MENU, Recalculate, ENTER.

If you have set your device to prompt you for the recalculation method, try Shorter Distance first. This worked better in one of my tests. Or set up the routing for shorter distance before you begin.

It seems to me that the Avoid Highways function actually has the much nicer meaning, "Avoid Highways for about 10 miles ahead". The device, in demo mode, nicely routes me off the freeway at the next exit, then routes me parallel to the freeway for something like 10 to 20 km, then it routes me back onto the freeway and keeps me on the freeway thereafter.

1 statute mile = 1.6 km
1 km = 0.621 statute miles

Don't forget to disable the Avoid Highways function again afterwards by removing that check mark, otherwise you'll be routed off the freeway again every time you calculate or recalculate a route.

When I use this function without being on a freeway, a similar thing happens. The device avoids entering any freeway for some 10 to 20 km, and after that distance it happily routes me via freeways.

The result is that there is no way to force the device to avoid freeways throughout, but the actually more useful function of circumventing a blocked road is there. (You can tell it you're riding a bicycle, which could have the effect that you're routed along rather narrow paths and tiny streets, but even that doesn't keep you off freeways persistently. It still leads you onto a freeway, albeit much later.)

However, I have tested this only with the European City Select v6 and have one report from the US where it didn't work with the US City Navigator v5. It is as yet unclear why it doesn't seem to work everywhere. Please send me an email if you have tested this and let me know how it worked for you.

Find City Outside Base Map Workaround

There is a workaround for the defect in these devices in the Find City function. It does not work outside the main base map area.

I am not sure whether the workaround works in all 60/76/96 C/CS devices. I tested it only on the 76C. But since they are quite similar, I guess it works on the others as well.

The defect is that these devices with their default settings do not use loaded maps to find cities by name. They do find the nearest cities in the loaded maps, but that's a different function.

Why would you want to find a city outside your base map? Mainly because you're travelling or because you bought the Americas version for use in another area because it's cheaper.

First of all, if you know any street address in the city you want to find, then you can use the Find Address function instead. But what can you do when you don't know any street name?

The function you need is actually there, but it is improperly implemented and therefore hard to find. Use the following sequence:

1. FIND, Cities, ENTER
2. MENU, Find By Name, ENTER
3. MENU, Select Map, ENTER, (Select your local City Select map.), ENTER
4. MENU, Find By Name, ENTER (Yes, you have to enter this command a second time.)

It looks like two programming defects to me. One is that the Best Map doesn't work, the other is that the first time you select Find By Name, the map choice is reset. It works only the second time.

How Does TracBack Work?

First, when you save the track, the device asks you whether you want to save the entire track or only a part.

If you select a part, it asks you to point to the beginning and end points of the piece you want to save. You only have to point roughly near the right spot, and it will offer you a menu choice of precise times of track points near your pointer.

After this you have a saved, non-directional track, something like a piece of road to drive on.

Now you have to set the device's routing method to off-road or prompted routing, otherwise the saved track will simply be ignored and a new route calculated.

When you select the TracBack function for that saved track, the device will ask you to point to your desired destination on or near the saved track.

The device will then route you from your current position towards the nearest point in the saved track, then along the track to your destination point.

Some More Little Points

I found the manual totally useless. It doesn't contain any information you cannot deduce from trying out the device and going through the menus. It doesn't give any useful hints. It doesn't contain any detailed information about any function, like for example the Avoid Highways function, it doesn't contain the assumptions behind some settings—nothing. I think, Garmin could do a bit better here.

I guess that the functions or workarounds I described above is actually quite useful, but 90% of all users will not get this idea because they don't have the time to play around with the device like I just did. What a pity! Naming the functions better would also helped. Instead of Avoid Highways it might have been named Circumvent Road Block on Highway or simply Highway Blocked, and it should not be a check mark, but a one time button.

Magne W. Mathisen did some more tests and found a few useful facts. Thanks, Magne!

• MapSource 6.3 apparently uses the same routing algorithm as the GPS receivers—the results are the same.
• If you set your vehicle type to Truck, the algorithm has a much stronger tendency to route over freeways.

I also found a few more little tricks.

• If you set your vehicle type to Bicycle, the device will try to route you along the very shortest route, even using the smallest residential streets. The Car/Motorcycle setting avoids those and routes over the next bigger road size where possible.
• Sometimes after calculating several routes always to the same destination the device ignores the settings and stubbornly sticks to the last route it has calculated. If that happens, you have to give it a different destination, calculate a route, then go back to the original destination (FIND, FIND, down) and calculate again. That will clear its sticky memory.

Virtual Geocache on the Equator

For general information on geocaching please see www.geocaching.com. The listing of this geocache on that site is here. For more information on travelling in Kenya please see www.michna.com/kenya.htm. For travel reports please see www.michna.com/kenya2004.

This is a description of the first equatorial divine (a fun abbreviation of “dividing line”) geocache, i.e. the first geocache placed where an integer meridian crosses the equator, which is at the same time the first virtual geocache. The coordinates are N/S 0° E 36°.

Due to the people who live in the area, it is not possible to actually stash away anything. Thus we have the first virtual geocache now. Approx. 40 m to the south of the meridian-equator crossing there is a tree. I carved a short message into its bark on the northern side in big letters, several inches in size, easy to read. (Took me almost an hour.) Whoever sends me an email with the text will get entered into the virtual logbook for that geocache and published here, on anybody else’s Web site who wants it, and in the sci.geo.satellite-nav newsgroup. You can also email me.

When you find the geocache, please take a knife and improve the letters a little by carving them a bit deeper to keep them easily visible. The bark and wood is hard, but a sharp knife does the job.

A small hint—at first I went there the hard way, by pointing my jeep straight towards the point, off about 90° from the nearby main road, and driving straignt towards it. It’s only a few kilometers, but it took me hours of rather difficult driving including turning back once and crossing a river, where I had to drive through the water, then up a steep slope such that I was seriously worried about the jeep falling over backwards.

After finding the place, it turned out that there is at least one easier way to get there. Getting back to the road took me much less than an hour. A good map would help. So don’t do it the hard way. The shortest way is not always the fastest.

Twice I found it impossible to reach by car after it had rained.

But then I don’t expect this geocache to be found all too often, if ever. (Now that it has been found already several times, my preceding sentence, of course, looks overpessimistic.)

The virtual geocache logbook is here:

Send Mail

Please measure the waypoints again if you pass by and let me have your coordinates, so the accuracy can be improved. Of course I am always interested in more good waypoints and routes. Please click on the E-Mail symbol below to send me mail.

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