Notes on the Garmin Etrex Vista H

Notes on the Garmin Etrex Vista H

September 7 2009 edition
Steve Seibel
steve at aeroexperiments.org
www.aeroexperiments.org

 

 

1) Introduction

 

2) No NMEA output

 

3) Color vs non-color-- notes on screen size and shape of various Etrex's.

 

4) New features of the Legend H, Vista H, etc.

 

5) Disadvantages of the Legend H, Vista H, etc over older Etrex's.

 

6) Hiking with the Etrex Vista H

 

7) Flying with the Etrex Vista H

 

8) Some other pros and cons of the Garmin Etrex Vista H compared with the GPSmap 76S

 

9) Durability

 

10) Mounting and antenna performance

 

11) Notes on the various display screens

 

12) Adding a "Find" page to facilitate the "goto" function

 

13) Routes

 

14) Turning off the magnetic compass

 

15) “Heading”, "bearing", and “course”

 

16) “Current glide ratio” and “glide ratio to destination” displays

 

17) “Estimated time of arrival” computer

 

18) "Battery saver" mode

 

19) Notes on track logs: “active logs” and “saved tracks”

 

20) Notes on waypoints

 

21) List of settings

 

22) Additional notes on track logs: uploading “active logs” and “saved tracks” from MapSource to the GPSmap 76S

 

23) Additional notes on MapSource 6.9.1

 

24) Additional links

 

 

 

1) Introduction

 

This article is intended to supplement the related article on this website entitled “Using a GPS in soaring flight”, by providing some additional information that is specific to the Garmin Etrex Vista H.  Again, our focus will be mostly on using the GPS during soaring flight, but much of the information given here will pertain to other applications as well, including powered flight. We'll also consider other uses.

The software version on the Etrex Vista examined for this article was 3.60.

Some, but not all, of our comments about the Etrex Vista H and other H-series Etrex's will also apply to the Etrex's with color screens like the Etrex Vista HCx. All these units share similar menu architecture and have similar features, with the most significant difference between the color and non-color units being the size and shape of the display screen.

 

 

2) No NMEA output

 

The unlike the older Garmin Etrex Legend, Vista, etc, the Garmin Etrex Vista H, HCx, and other Garmin Etrex "H" and "HCx"-series GPS's have no NMEA output capability. Therefore they cannot be interfaced with a Brauniger IQ Comp GPS variometer or other similar device. They are not suitable for use as the sole or primary GPS during soaring flight for pilots who need this capability.

 

 

3) Color vs non-color-- notes on screen size and shape of various Etrex's.

 

I've long been a fan of the Garmin Etrex series both for flying and hiking. I prefer the classic, non-color versions to the color versions, because the color versions (Legend HCx, Vista HCx, etc) have a wider, shorter screen than the non-color versions (Legend, Legend H, Vista, Vista H, etc). The wider, shorter screen of the color versions gives a larger map display when no numerical data fields are enabled, but is poorly suited to displaying numerical data fields on the map screen. The taller, narrower screen of the non-color versions is slightly smaller than the color screen, but the shape leaves much more screen area for the map display when three or more data fields (including the "guidance text" field) are enabled. For more on this, see the related article on this website entitled “Map screen size comparison of some handheld Garmin GPS units with numerical data fields enabled”. I find it very useful to display several numerical fields both for flying and hiking-- values of interest often include speed, heading, distance, bearing, GPS accuracy, current glide ratio, or glide ratio to target. I also feel that the non-color versions are slightly easier to view with the back light off in some light conditions.

 

 

4) New features of the Legend H, Vista H, etc.

 

The classic non-color Etrex's (Legend, Vista, etc) have recently been redesigned into new versions (Legend H, Vista H, etc) that include some of the features of the color versions (Legend HCx, Vista HCx, etc), while still retaining the original tall screen shape as described above. The best new feature is a dramatic increase in antennae sensitivity. This vastly improves the functioning of the GPS in deep forest, and also in a vehicle or airplane where the view of the sky is restricted. There is also a noticeable decrease in the lag time required for the GPS to indicate a change in speed or direction of travel-- the lag time seems to be approximately .5 seconds with the newer versions and approximately 1 second with the older versions. Other nice improvements are the ability to display 4 rather than only 2 numerical data fields (plus the guidance text) on the map screen, the ability to display 4 rather than only 2 numerical data fields on the compass screen, and easier access to "panning" feature on map screen. The color versions (Legend HCx, Vista HCx, etc) also share all these advantages with the new non-color versions (Legend H, Vista H, etc.)

Other advantages of the new non-color Etrex versions (Legend H, Vista H, etc) over the older versions (Legend, Vista, etc) include the following: USB data port.

 

 

5) Disadvantages of the Legend H, Vista H, etc over older Etrex's.

 

There are some things I don't like about the Legend H, Vista H, etc in comparison to the older versions (Legend, Vista, etc).

Although it is easier to start panning the map with the newer version, it is harder to drop a waypoint at some desired point while panning. This is true of all the "H" (non-color) and "HCx" (color) Etrex's.

A more serious problem with all the newer "H" and "HCx" Etrex's is that whenever the user creates a new waypoint, the "goto" function is not immediately available. Instead, 4 or more further operations are needed to go to the "find waypoints" menu, select the new point from the list of nearest waypoints, and activate the "goto" function. This is often inconvenient. For example, while flying over some point of interest on the ground a pilot may wish to drop a waypoint and activate the "goto" function, so he can easily return to the point. Likewise a pilot may wish to quickly activate the "goto" function to stay near a point of strong lift while flying in wave. The multiple operations needed to accomplish this limit the utility of the Legend H, Vista H, and all other "H" and "HCx" Etrex's in these particular situations. The GPSmap76CSx also suffers from this problem, while the older GPSmap76 and the older Etrex Legend, Vista etc give immediate access to the "goto" function when a new waypoint is created.

I've found that the Vista H locks up from time to time. Sometimes it recovers after a few tens of seconds but other times the batteries must be removed before the unit can be restarted. I had this problem less frequently with my GPSmap76S, and almost never with my older Etrex Legend and Vista.

As noted above, the "H" and "HCx" Etrex's do not offer NMEA output, which will eliminate these units as a good choice for a primary GPS for soaring pilots who need to interface with a vario or flight computer requiring NMEA output.

 

 6) Hiking with the Etrex Vista H

 

I find the Etrex Vista H to be a really great choice for hiking and field work. As with all Etrex's, the buttons are readily available for one-handed operation, and the compact size of the unit is really nice. The antenna sensitivity and accuracy of all the Etrex "H" and "HCx" products has been dramatically improved over the older Etrex's. The Etrex Legend H offers all the same features as the Vista H, minus the magnetic compass and the barometric altimeter. The barometric altimeter is not needed for hiking, but is needed to drive the current-glide-ratio and glide-ratio-to-target displays, which pilots will appreciate. The magnetic compass should always be turned off for flight, and is not really needed for hiking if a separate magnetic compass is available, but it really is quite nice to have the pointer on the map always point in the same direction that the GPS unit is actually pointing. Without the magnetic compass, the direction of the pointer will change erratically when a hiker is moving at a very slow speed, such as while bushwhacking through heavy brush. Therefore the magnetic compass feature does allow a hiker to travel in a desired direction more efficiently, without the need to frequently check a separate magnetic compass. When battery drain is an issue, the compass should be turned off-- therefore users who value simplicity as well as functionality might find the Etrex Legend H to be a better choice.

 

 

7) Flying with the Etrex Vista H

 

I also use the Vista H as a back-up GPS while hang gliding. The high sensitivity of the antennae gives me confidence that reception is unlikely to be lost. Besides simply losing reception for a brief interval, I've actually my primary Garmin GPSmap 76S completely lock up on me several times and it was nice to have a second GPS so that my track log was not lost. As an aid during the unlikely event of inadvertent flight in cloud, I also like to be able to have a second GPS set to the compass-like heading display screen, while the primary GPS displays the map. This provides maximum situational awareness, and takes advantage of the fact that the compass-like heading display screen is more intuitive to read, and updates faster, than the small heading pointer on the map screen. (See the related article on this website entitled "Emergency tools and strategies for cloud flying without gyro instruments in "conventional" aircraft and hang gliders" for more.) The high sensitivity and fast responsiveness of the Vista H makes it a good choice for this secondary display. (The Legend H would also be more than adequate for this function, which does not require the magnetic compass or barometric sensor. If I never planned to use my GPS for hiking or field work, I would have chosen the Legend H for my backup GPS.) The ability of the Legend H and Vista H to display 4 numerical data fields on the map screen and compass screen also makes them a good choice for flight applications, and is a nice improvement over the older Legend and Etrex.

I do find the older Garmin GPSmap76S to be a better choice for my primary GPS in flight, especially while hang gliding. Some of the features offered by the Garmin GPSmap76S (and also the Garmin GPSmap76CSx) but not the Vista H include: larger screen size, larger front-mounted buttons that are more readily accessible when the GPS is in a fixed mount and are also easier to access with gloved hands, and NMEA output. Some of the features offered by the Garmin GPSmap 76S but not the GPSmap76CSx or the Garmin Vista H include: menu architecture optimized to simplify activating "goto" function to a newly-created waypoint, and 6 or 9 small numerical data fields available on map screen.

However, the ease of one-handed use of all the Etrex products can be a real advantage in any situation where the GPS cannot be mounted in place, as long as heavy gloves are not needed. For example, in a rented or club-owned sailplane it is convenient for the pilot to hold an Etrex in his free hand as it rests upon the canopy sill. The improved antennae sensitivity of the Vista H is a real "plus" for use inside a car or airplane where the view of the sky is compromised due to the structure of the vehicle. Due to this improved sensitivity, the Vista H (and other Etrex "H" and "HCx" products, as well as the GPSMap76CSx) are much more tolerant of a poor view of the sky than are the GPSMap76S or the older Etrex products, and this allows the unit to be placed in a location that gives optimum ergonomics and ease of viewing rather than in a location that gives optimum reception. With the older Etrex's or the GPSMap76S, I've found that sometimes reception is unsatisfactory in a high-winged aircraft unless the unit is held far forward over the dashboard. I've also found the reception with these older units to be marginal even in the rear seat of a mid-winged 2-32 sailplane with a bubble canopy, due to the high metal walls of the fuselage.

 

 

8) Some other pros and cons of the Garmin Etrex Vista H compared with the GPSmap 76S

 

Above, in "Disadvantages of the Legend H, Vista H, etc over older Etrex's" and "Flying with the Etrex Vista H", we described some issues relating to antenna sensitivity, ergonomics, screen size, number of numerical data fields available on the map screen, ease of activating a "goto" function to a new waypoint, and availability of NMEA output. Here are some other pros and cons of the Etrex Vista H in comparison to the GPSmap 76S.

 

Some “pros” of the Etrex Vista H in comparison to the GPSmap 76S:

 

* On the entire Etrex series (including the newer "H" and "HCx" models), as well as on the GPSmap 76C/Cx/CS/CSx and the GPS60C/Cx/CS/CSx, the heading indicator display can be configured as an HSI-style display that shows the course line pointer and the distance off course, or as a simpler display with a “bearing” pointer.  The HSI-style display with the course line pointer is of no value during soaring flight, but could be useful while flying a powered aircraft along airways or other defined routes.  The GPSmap 76S’s heading indicator display always features a “bearing” pointer, but cannot be configured as an HSI-style display that shows the course line pointer and the distance off course.

 

* On the entire Etrex series (including the newer "H" and "HCx" models), as well as on the GPSmap 76C/Cx/CS/CSx and the GPS60C/Cx/CS/CSx, the battery life indicator is adjustable to read accurately for NiMH, NiCad, and Lithium batteries as well as alkaline batteries.  This is not the case with the GPSmap 76S.

 

* On the entire Etrex series (including the newer "H" and "HCx" models), as well as on the GPSmap 76C/Cx/CS/CSx and the GPS60C/Cx/CS/CSx, “sunrise” and “sunset” are included as options for the various numerical data fields.  This is not the case with the GPSmap 76S, though sunrise and sunset times can still be viewed by going to the "Celestial" menu.

* USB port for high-speed data transfer.

 

 

Some “cons” of the Etrex Vista H in comparison to the GPSmap 76S:

 

* No tide-related features

 

 

9) Durability

 

The rubber sealing strip that wraps around the Etrex series GPS’s tends to come unglued and/or tear apart after several years of hard use, especially in hot weather, and especially if the tab on this rubber strip is frequently lifted up to expose the interface/ external power port.  Once this rubber strip starts to tear and/or separate, the GPS unit becomes hard to operate, because all the buttons are molded into this strip.  I’ve owned 4 different Etrex series GPS’s, and all eventually sported lots of duct tape to hold this damaged rubber strip firmly in place. The factory did refurbish the units for a modest fee when I finally sent them in.

 

I've experienced two other problems with my Etrex series GPS's after several years of hard use: on one of my GPS’s, the joystick developed an intermittent problem where it would only respond to 2 out of the possible 4 directions of movement (e.g. the cursor would respond when the joystick was moved left or down, but not when the joystick was moved right or up.)  Two of my Etrex series GPS’s developed intermittent problems with the display screens becoming obscured by spurious lines.

 

 

10) Notes on mounting and antenna performance

 

The Etrex series uses a patch antenna, which is positioned optimally when the display is facing upwards. The Visa H and other "H" and "HCx" Etrex's have such good reception that the exact positioning and orientation of the unit will seldom be an issue, even inside a car or an airplane. I’ve generally had acceptable results using the Vista H in a high-winged airplane, simply holding the unit in one hand, but I’ve occasionally had to reach forward and hold the unit in an awkward fashion to keep it far enough forward in the windscreen area to get uninterrupted satellite reception. This happens much less often with the Vista H than with the older Vista. For hang gliding, I like to mount my GPS on the right downtube, in a sideways orientation, with the long axis of the GPS pointing forward rather than up. (Photo to be added.) I find that this makes the display more intuitive to interpret in flight. To optimize reception, I find that it helps to tilt the Etrex Vista so that the display faces partially upwards instead purely sideways, facing a spot lying about 45 degrees between the horizon and the zenith, so that the patch antenna has a better view of the sky.  (Photo.)  This still gives me a good view of the GPS display, and gives satisfactory satellite reception, except that in a steep left turn the satellite reception is occasionally compromised. 

 

When satellite reception is marginal, the “vertical speed” and "current glide ratio” functions will be the first functions to fail.  For more on this, see the section of this article entitled "'Current glide ratio' and 'glide ratio to destination' displays". The satellite reception of the Vista H and other "H" and "HCx"-series Etrex's is so good that this is rarely an issue.

I use a very simple mounting system for my Etrex GPS's-- I drill a single hole through the center of the battery cover, and pass a 6-32 size machine screw through the hole with the head captured inside the battery compartment. This requires cutting away the plastic reinforcing ridge inside the battery compartment to allow the screw head to sit flush with the inside of the battery cover. I then pass this screw through a hole in a piece of sheet metal attached to my vario mount, and use a wingnut to secure the GPS in place on the sheet metal. If the fastener for the battery cover were to fail, the GPS would be lost, but I've never had this problem in years of using this system. (Photos to be attached.) 

 

11) Notes on the various display screens

 

As described in the related article on this website entitled “Using a GPS in soaring flight”, the map display screen is very useful.  The compass-like heading display screen can also be useful in some situations.  I never use the elevation screen in flight.  The numerical data page can display 9 different numerical fields and is a handy place to display additional numerical data fields that don’t fit on the moving map screen or heading display screen.  I usually configure the 4 numerical fields on the map screen to “glide ratio”, “glide ratio to destination”, "speed", and "heading". I usually configure the 4 numerical data fields on the compass-like heading display screen to show “heading”, “speed”, "bearing", and "distance". Other values that are sometimes of interest include "accuracy of GPS", "current destination" (if the guidance text on the map is not enabled), "current ETA", "sunrise", "sunset", "time of day", and "vertical speed".

 

 

12) Adding a "Find" page to facilitate the "goto" function

When using a GPS in flight, it is sometimes useful for a pilot to be able to quickly create a new waypoint and activate a "goto" function to that waypoint. For example, while flying over some point of interest on the ground a pilot may wish to drop a waypoint and activate the "goto" function, so he can easily return to the point. Likewise a pilot may wish to quickly activate the "goto" function to stay near a point of strong lift while flying in wave. With all the newer Etrex GPS's, such as the Legend H, Vista H, Legend HCx, and Vista HCx, this takes quite a few operations to accomplish. As the units come out of the box, this takes at least 7 operations in total, and possibly several more, depending on the order of the icons on the menu screen. With all of these newer Etrex units, the total number of operations required to create a waypoint and activate a "goto" function to that waypoint can be reduced to 6 by inserting a "find" page behind the map page, and using the upper right button to go directly to the "find" page from the "map" page immediately after creating the new waypoint. To add or delete pages to the page sequence, go to the "Setup" menu and select "page sequence".

 

 

13) “Routes”

 

One thing the reader won’t find in this article is a close examination of the “route” feature of the Etrex Vista.  A good understanding of this feature may be helpful for a contest soaring task involving several waypoints, or during a cross-country flight in an airplane.  I prefer to simply use my GPS in the basic “goto” mode.  If need to change my target destination during the course of a flight, I manually set the GPS to “goto” the new waypoint at the appropriate moment.

 

 

14) Turning off the magnetic compass

 

The magnetic compass sensor should be switched off before flight, since it is subject to the same banking-related errors that a conventional wet compass is subject to, and will behave very erratically during turns.  It is important that the magnetic compass sensor remain off even if the groundspeed happens to drop near zero momentarily.  A GPS-driven heading display will naturally behave erratically whenever the groundspeed approaches zero, but in the context of a vehicle that turns by banking, the situation becomes even worse if the heading display is switching back forth between being driven from the GPS satellites and being driven by the magnetic compass sensor.

 

With the Etrex Vista, Vista H, GPSMap76S,GPSMap76Csx, etc, 2 different conditions must be satisfied for the magnetic compass to be activated.  If either of these two conditions is not met, the magnetic compass will remain off. 

 

The first of these conditions is that the time-speed interlock must be satisfied.  The time-speed interlock parameters are displayed on the “heading” submenu of the “setup” menu.  The text reads: “Switch to compass heading when below (X) for more than (Y).”  (The letters “X” and “Y” do not actually appear in the text.)  For flight, and any other time I want to ensure that the magnetic compass stays off, I set X equal to the lowest possible value, which is 0 mph, and I set Y equal to the greatest possible value, which is 180 seconds.  If I wanted to allow the compass to be turned on whenever the user wished, I would set X equal to the greatest possible value, which is 99 mph, and I would set Y equal to the smallest possible value, which is 5 seconds. These conditions will nearly always be satisfied, except during flight in an airplane-- when the magnetic compass would not work correctly anyway.  Setting the time-speed values to 10 mph and 5 seconds will enable to the compass to be turned on when the user is hiking and will cause the magnetic compass to be off whenever the GPS is in a moving vehicle. This might be convenient for some applications. The magnetic compass is convenient because it makes for a more stable display of "heading" while travelling at low speeds on foot, so long as the GPS unit is held level, but the magnetic compass also increases the drain on the batteries.

 

The second condition that must be met for the magnetic compass to be activated is that what we’ll call the “compass on/off toggle” must be set to the “on” position.  The position of this “toggle”, which can be either “on” or “off”, is not displayed in any of the Vista H's menus.  The user can flip this toggle on and off at will by holding down the upper right button for several seconds.  This will cause a message to appear on the screen saying "compass turned off" or "compass turned on".  Regardless of the message, the compass will not really be on unless the time-speed parameters are also met.  It is easy to accidentally flip this toggle while using the various buttons of the GPS.  If this happens, the user can ignore this message if he or she is sure that the time-speed parameters do not actually allow the compass to stay on, or the user can simply press the upper right button again to be sure that the compass is turned off.  By using this button, the user can make sure the compass is only on when actually needed, saving batteries, regardless of the setting of the time-speed interlock. Again, the magnetic compass will only stay on when the time-speed interlock is satisfied AND the on/off toggle controlled by the upper right button is set to "on". By setting the time-speed interlock to the maximum values noted above and leaving toggle in the "off" position, the user can make sure the magnetic compass will never accidentally get turned on.

 

 

15) “Heading”, “bearing”, and “course”

 

GPS users should understand that in the absence of a magnetic compass function, a GPS unit cannot really measure “heading”, only direction of travel over the ground.

 

With the Etrex Vista (and Vista H and HCx), when the magnetic compass sensor is on, Garmin uses the word “heading” to mean the direction that the nose of the aircraft (or more precisely, the “nose” of the GPS) is pointing.  When the magnetic compass sensor is on, the Etrex Vista cannot display the current direction of travel over the ground, except in the form of the “breadcrumb trail” that is laid down on the map screen.  When the magnetic compass is switched off—which it always should be during flight—then the word “heading” refers to the current direction of travel over the ground, as derived from the GPS satellites.

 

The heading indicator display—i.e. the display that looks like a compass—displays “heading”, as defined above.  When the magnetic compass is switched off, this will reflect the direction of travel over the ground.

 

The “bearing” is the direction to the target waypoint at any given moment.

 

Now we’ll take a moment to define the concept of a “course” line, as used by Garmin in the context of the GPSmap series and other similar handheld GPS units:  at the moment that a “goto” function is activated, a fixed “course” line is created, which is the line extending from the aircraft’s location at moment that the “goto” function was started, to the target waypoint.  Once a “goto” function has been activated, as the aircraft continues to fly, the “bearing” to the target waypoint may change, but the “course” line remains completely fixed in space, until the navigation to the waypoint is discontinued or re-started with the same waypoint or with a different waypoint.  Even if the aircraft strays “off course” by many miles, the numerical reading in the “course” data field (if present) will remain fixed until the navigation to the waypoint is discontinued or re-started with the same waypoint or with a different waypoint. 

 

With Etrex Vista (and Vista H and HCx), the user can configure the GPS so that either a “course line” or a “bearing line” appears on the map screen when the GPS is navigating toward a waypoint.  As noted above, the “course line” remains fixed in place on the map, while the “bearing line” moves so that one end is always attached to the aircraft icon, while the other end remains fixed at the destination waypoint. 

 

The user can also configure the GPS so the either a “course pointer” or a “bearing pointer” appears on the heading indicator display.  The “course pointer” is an HSI-style display: the orientation of the course line pointer remains fixed with relation to the azimuth dial, but the course line pointer slides sideways to show that the aircraft is “off course”. 

 

For soaring flight, I always choose the “bearing” option for both the map screen and the heading display screen.  In fact, for soaring flight, I almost never allow my GPS to display any information relating to “course”; I’m generally much more interested in the “bearing” from my current position to the destination waypoint.

 

 

16) “Current glide ratio” and “glide ratio to destination” displays

 

Garmin handheld GPS's with barometric pressure sensors, including the Garmin GPSmap 76S, GPSmap76C/Cx/CS/CSx, GPSmap60/60C/Cx/CS/CSx, and Etrex Vista/ Vista H/ Vista HCX, include "current glide ratio" and "glide ratio to destination" displays.  These functions are quite useful.  By comparing the two numbers, one can get a sense of whether the glider will reach the target with altitude to spare, or will not have enough altitude to reach the target. 

                       

The “current glide ratio” display on these GPS’s is extremely responsive.  This is a mixed blessing.  In very smooth air, the effects of a change in airspeed can be seen almost instantly, after waiting just a few seconds for the aircraft's sink rate to stabilize.  In turbulent air the display is so “twitchy” that it is not really very useful for fine-tuning the pilot’s choice of speed-to-fly.  It would be nice if the user could select for the “current glide ratio display” to be averaged over a slightly longer time interval on these GPS’s, so that it would function more like the digital “current glide ratio” display on some GPS-compatible variometers like the Brauniger IQ Comp GPS.  This would make the “current glide ratio” display slightly more useable for fine-tuning the pilot’s choice of speed-to-fly.  However, even in turbulent air, and even given the “twitchiness” in the “current glide ratio” display, a rough comparison of the “current glide ratio” with the “glide ratio to destination” will give a good idea of whether or not the glider is currently on a glide path that will reach the target destination with altitude to spare or fall short of the target destination, assuming that the current atmospheric conditions will continue all the way to the target. 

 

A "glide ratio to destination” display is always intrinsically much more stable than a "current glide ratio" display, because the "glide ratio to destination " function depends only on the glider's position in space relative to the target, not on the glider's horizontal and vertical velocities.  The “glide ratio to destination” display is not dependent upon an accurate measurement of the glider’s vertical speed at any given moment.  An updraft or downdraft can produce a very large, immediate change in the “current glide ratio”, but will only produce a gradual change in the “glide ratio to destination.” 

 

A long-term trend in the “glide ratio to destination” function gives a pilot some useful information.  For example, in a sailplane, if a pilot sees the “glide ratio to target” slowly scroll from “30” down to “25” over the course of several minutes, this indicates that the glider will overfly the target with altitude to spare, assuming that the current atmospheric conditions continue all the way to the target.  Conversely, if the pilot sees the “glide ratio to destination” slowly scroll from “30” up to “35” over the course of several minutes, this indicates that the glider will run out of altitude before reaching the target, assuming that the current atmospheric conditions continue all the way to the target.  For hang gliding and paragliding applications where glide ratios are often below 10:1 and can even drop to 5:1 or less when a strong headwind is present, a “tenths” digit in the “glide ratio to destination t” display is very useful for helping a pilot to detect slow trends in the “glide ratio to destination” display.  For example, if over a period of several minutes, the “glide ratio to destination” figure slowly scrolls from "4.8" to "4.7" to "4.6", this lets the pilot know that he will overfly the target with altitude to spare, assuming that the current atmospheric conditions continue all the way to the target.  On the other hand, if over a period of several minutes, the “glide ratio to destination” figure slowly scrolls from "4.7" to "4.8" to "4.9", this lets the pilot know that he will not be able to reach the target, if the current atmospheric conditions continue all the way to the target.  For hang gliding and paragliding applications, a “glide ratio to destination” display is significantly more useful if it has a “tenths” digit, than if it does not. 

 

The “glide ratio to destination” display on handheld Garmin GPS’s with pressure sensors does not include a “tenths” digit.  Perhaps in a future software update for these GPS units, Garmin will create a “tenths” digit for the “glide ratio to destination” function, at least in cases where the glide ratio to target has dropped below 10:1.  In fact this would be my number one suggestion to Garmin for improving the functionality of their GPS’s for hang gliding and paragliding applications.

                       

Pilots may occasionally encounter a rather peculiar problem with the “current glide ratio” function on handheld Garmin GPS’s with barometric pressure sensors-- if the satellite reception is poor, the “vertical speed” display will scroll to zero and the “current glide ratio” display will scroll to infinity.  For more, see the related article on this website entitled “Notes on the glide ratio functions of some Garmin GPS receivers with pressure sensors”.  For most soaring applications, the satellite reception is good enough that this problem is rarely encountered.  However, I’ve occasionally encountered this problem when flying with my older Etrex Vista attached to the down tube of my hang glider.  I’ve always been able to cure this by changing the angle of the mount so that the face of the Vista pointed more upwards and less sideways.

                       

Since this problem is related to the quality of the reception of the GPS signal, it will probably be very uncommon in GPS units with high-sensitivity receivers, such as the Vista H, Vista HCx, and GPSmap76CSx.

 

 

17) “Estimated time of arrival” computer

 

The “estimated time of arrival” computer isn’t useful for soaring flight, but it is useful during cross-country flight in an airplane, where it seems to be quite accurate.  The “estimated time of arrival” computer even seems quite accurate during most driving situations, even when it is not possible to travel directly toward the destination (e.g. the roads run north-south and east-west and the destination lies to the northwest.)  The computer doesn’t seem to rely too heavily on the velocity made good toward the destination at any given moment.  The behavior of the “estimated time of arrival” computer seems roughly consistent with the following model: an eta computer could be programmed to assume that the vehicle will continue travelling at its current speed and direction until the target destination lies abeam the current direction of travel, and then will turn 90 degrees and travel directly toward the target destination, keeping the same forward speed.

                       

 

18) “Battery save” mode

 

The Etrex Vista H doesn't have a user-selectable "battery save" mode. Garmin appears to have done a good job of engineering the GPS for good responsiveness combined with long battery life.

 

 

19) Notes on track logs: “active logs” and “saved tracks”

 

We’ll now turn our attention to the track logs generated by the Garmin Etrex Vista H.  The Vista generates two different kinds of track logs, both of which can be accessed by downloading the GPS data to the “MapSource” program.  We’ll call these two different types of track logs the “active logs” and the “saved tracks”.

 

The phrase “active log” never appears on anywhere on the screen of the Etrex Vista H, but will be familiar to anyone who has downloaded data from the Vista to MapSource, as we’ll see shortly.  If the unit is being used in the “track off” mode, then no “active log” is being generated.  Otherwise, a new “active log” begins every time the GPS unit acquires a satellite lock, or loses the satellite lock, or is put into “GPS off” mode.  (After the unit loses the satellite lock or is put into “GPS off” mode, the location is assumed to be fixed at the last known position, but new altitude data continues to be recorded.)  Each “active log” is comprised of many individual “track points”.  For each “active log” track point, the GPS records time and date as well as location.  When an “active log” is viewed with the “MapSource” computer program, each “active log” track point is displayed along with the date, clock time (in hours, minutes, and seconds), altitude, leg length (i.e. distance to the next track point), leg time, leg speed, leg course (which in this context means the direction of travel to the next track point), and position (latitude and longitude).

 

The “active logs” are not listed on the GPS’s “tracks” menu.  However the “active logs” are used to draw the “breadcrumb trail” on the map screen of the GPS: the “breadcrumb trail” represents all the active logs that are currently stored in the GPS, and shows everywhere that the GPS has been since the track log was last cleared (or at least back to the oldest “active log” track point that has not yet been overwritten by newer track points.)  The “active logs” are also used to draw the altitude-versus-time plot or altitude-versus-distance plot on the “altitude” screen of the GPS.  Again, these plots show the entire history since the last time that the track log was cleared, back to the oldest “active log” track point that remains in the “active log” memory.

 

When GPS data is downloaded to MapSource, the “active logs” appear on MapSource’s “tracks” page, and have names like “ACTIVE LOG”, “ACTIVE LOG 001”, “ACTIVE LOG 002”, etc.  In MapSource, the user can re-name the active logs if he wishes.  In MapSource, the user can also select a specific active log to display as a track on the map or as an altitude-versus-distance plot.  MapSource cannot display an altitude-versus-time plot.  With MapSource, several different “active logs” can be joined together into one.  Active logs can be uploaded from MapSource to the GPS, as we’ll see in a later section of this article.

 

The Etrex Vista H can store up to 10,000 “active log” track points in all.  The fraction of the “active log” memory that has been used up is displayed near the top of the “tracks” menu screen near the words “track log”.  When there is no more room to record fresh “active logs” without overwriting older “active logs”, the “track log” memory indicator will read 100%.  Deleting some of the “saved tracks” that appear on the “tracks” menu screen has no influence on the amount of memory that is available for recording new “active logs”—the “saved tracks” and the “active logs” are stored in different memory areas, and the memory indicator near the top of the “tracks” menu screen refers only to the memory used by the “active logs”, not to the memory used by the “saved tracks.”  If the user has selected the “wrap when full” option on the “set up track log” menu, then once the “active log” memory space is full, the oldest “active log” will began to be over-written in a point-by-point fashion (i.e. the entire oldest “active log” will not disappear in one instant).  Pushing the “clear” button on the “tracks” menu screen will erase all the active logs and reset the “track log” memory indicator to zero.  Pushing the “clear” button on the “tracks” menu screen will not erase any of the “saved tracks” that are listed on the “tracks” menu screen.  We’ll discuss the “saved tracks” in more detail shortly.  After downloading the track log to a computer, it’s a good idea to push the “clear” button on the “tracks” menu screen to erase all the active logs, so that the “track log” memory indicator will be reset to zero.

 

In the “track log setup” menu, the user can control how often a new track point is added to the current “active log”.  The user can specify a time interval or a distance interval for adding new points to the “active log”.  However, I prefer to use a third option called “auto”. 

 

One of the chief advantages of the “auto” mode is that new active log points are added very infrequently (often only 2 per minute) when the GPS is not moving, so the user can switch the GPS on well before starting a flight and not worry that the active log memory is being needlessly consumed.  The only time this is not true is when the wind is gusty.  The barometric pressure sensor is affected by wind gusts, which create apparent changes in altitude, and trigger the recording of more track points.

 

In the “auto” mode, the GPS creates new “active log” track points at whatever rate is needed to create a high-resolution trace of the flight path.  New “active log” track points are added much more frequently when the direction of travel is rapidly changing (e.g. when a glider is thermalling) than when the direction of travel is nearly constant.  New “active log” track points are also added much more frequently when the speed of travel is rapidly changing (e.g. when an aircraft is flying in circles at a constant bank angle and airspeed, in a strong wind) than when the speed of travel is nearly constant.  Even if the vertical speed is roughly constant, new “active log” track points are added much more frequently when the altitude is changing than when the altitude is nearly constant.  If the vertical speed is changing rapidly rather than constant, new “active log” track points appear to be recorded more frequently than when the vertical speed is constant.

 

In the “auto” mode, the user can also select whether the “active log” track points are added “most often”, “more often”, “normal”, “less often”, or “least often”.  In some Garmin GPS units such as the Etrex Legend, I’ve found a marked difference (e.g. a factor of 2.4 or more) in the recording frequency between the “auto, most often” mode and the “auto, least often” mode.  Oddly enough, in the case of the Etrex Vista and the GPSmap 76S, the recording interval in the “auto, least often” mode seems to often be only about 1.4 times as long as the recording interval in the “auto, most often” mode, and often—especially during thermal flights with a great deal of circling-- the difference in the length of the recording interval between these two modes sometimes becomes almost negligible (e.g. a factor of 1.2). Also, with these 2 GPS units, there seems to be very little difference in the length of the recording interval between the “auto, normal” mode and the “auto, least often” mode.   With these 2 GPS units, when the “active log” track memory is starting to fill up, switching from “auto, most often” to “auto, normal” or “auto, least often” will not necessarily produce a dramatic increase in the amount of flight time that will fit into the remaining portion of the “active log” track memory.

 

Here are some examples of typical “active log” recording intervals for the Etrex Vista or GPSmap 76S in the “auto, most often” mode:

 

Example 1: shortest recording interval seen during a typical thermalling flight in a hang glider: one “active log” track point every second, which if sustained indefinitely, would yield only 2.8 hours of recording time.  I’ve only seen this high recording rate sustained for a minute or two at a time, typically during strong thermal climbs in strong wind.

 

Example 2: average recording interval over the entire length of a typical thermalling flight in a hang glider: one “active log” track point every 2 to 3 seconds, yielding 5.6 to 8.3 hours of recording time.  I’ve never seen the recording interval averaged over an entire flight in a hang glider drop below one “active log” track point every 2 seconds, so I suspect that a pilot can always count on at least 5.6 hours of recording time for a hang gliding flight.

 

Example 3: average recording interval during a ridge-soaring flight in a hang glider: one “active log” track point every 3.5 seconds or longer, yielding 9.7 or more hours of recording time.

 

Example 4: average recording interval over the entire length of a typical local thermalling flight in a low-performance sailplane: one “active log” track point every 2 to 3 seconds, yielding 5.6 to 8.3 hours of recording time.

 

Example 5: average recording interval during a flight segment in a light plane where the heading was roughly constant and the vertical speed changed frequently: one “active log” track point every second, yielding 2.8 hours of recording time.

 

Example 6: average recording interval during a prolonged full-power climb in a light plane, with a roughly constant airspeed and heading and vertical speed: one “active log” track point every 1.5 seconds, yielding 4.2 hours of recording time

 

Example 7: average recording interval during a high-speed flight segment in a light plane, where the speed, heading, and altitude were roughly constant: one “active log” track point every 5 seconds, yielding over 13 hours of recording time. 

 

Example 8: average recording interval while driving a car at highway speeds over a road with many long, straight, flat sections: one “active log” track point every 4 seconds, yielding over 11 hours of recording time

 

It’s interesting to speculate whether a paraglider, hang glider, or sailplane would tend to experience the shortest “active log” recording interval during thermalling flight.  I suspect that a lower-speed aircraft would generally experience a shorter “active log” recording interval than a higher-speed aircraft, because the lower-speed aircraft experiences a higher turn rate for a given bank angle than a higher-speed aircraft does.  However, a given angular change in heading creates a greater change in predicted position when the speed of travel is high than when the speed of travel is low, so perhaps the “active log” recording interval during circling flight ends up being relatively independent of airspeed.  I’ve collected less data for sailplanes than for hang gliders, but as far as I’ve been able to tell, the average “active log” recording interval for both of these aircraft types has been roughly similar during thermalling flight.

 

In summary, when using the “auto, most often” mode a pilot can generally expect to get at least 5.5 hours of “active log” recording time for most flights in light airplanes, sailplanes, hang gliders, and paragliders, and can generally expect over 9 hours of “active log” recording time while ridge-soaring.  However in certain situations the “active log” track recording interval can fall to one point every second, which only yields 2.8 hours of recording time.  It would be very unusual for the GPS to use this high recording rate over the length of an entire flight, but this might be possible if the flight followed a very unusual profile such as series of extremely rapid climbs and descents, e.g. during aerobatics.  Switching to the “auto, least often” recording mode will produce some increase in the amount of available recording time, but the increase will not necessarily be very large.  If a pilot wants to be sure that the GPS will retain a set of “active logs” that span the entire length of a flight, he should set the GPS to the “time” mode rather than the “auto” mode if the flight will likely be longer than 5.5 hours, or in the case of a ridge soaring flight in a hang glider, longer than 9 hours, or in the case of a flight involving an unusual number of very rapid climbs and descents (e.g. during aerobatics), longer than 2.8 hours.

 

During the course of a long flight, if a pilot is concerned about over-writing the start of the first “active log”, he can bring up the “tracks” menu to see what fraction of the “active log” memory remains, and he can then change the “active log” track recording interval if necessary.  Of course, this strategy only works if the pilot has selected the “clear track log” option before flight, or after the last time he downloaded the GPS data to a computer, so that there are no old unwanted “active logs” sitting in the “active log” memory area.

 

I normally set my GPS to record in the “auto, most often” mode.  If my actual time in flight exceeds 5 hours (or 9 hours during a ridge-soaring flight in a hang glider),  I make a point of checking the amount of space remaining in the “active log” memory every half hour or so.  If I see that the “active log” memory is approaching 90% full, I change the “active log” recording interval to the “time, 20 seconds” mode.  With 1000 “active log” track points remaining, this yields 20,000 seconds or 5.6 hours of additional recording time. 

 

When the “active log” memory is running low, another alternative is to simply use the “save track” option in flight.  As we’ll see in a moment, the “saved tracks” created by this method are separate from the “active logs” that we’ve been discussing, and contain less detail than the “active logs”, but at least some record of the start of the flight will be preserved even if the corresponding “active log” track points are overwritten.

 

Of course, another strategy is simply to use the “time” recording mode rather than the “auto” recording mode.  For example, a recording interval of 3, 4, or 5 seconds will allow the GPS to retain “active logs” spanning 8.3 hours, 11.1 hours, or over 12 hours respectively, and a recording interval of 10 seconds will allow the GPS to retain “active logs” spanning more than 24 hours.  One of these might be a good setting for a second, “backup” GPS.  For a multi-day flying trip where the user has no access to a computer for downloading GPS data, an even longer recording interval might be appropriate.

 

None of these adjustments to the rate at which new track points are added to the “active log” has any effect on the rate at which the map display screen is updated, or on the rate at which the numerical data display fields are updated, or on the rate at which new data is sent out through the data port to an attached variometer, barograph, etc.  The numerical data fields, moving map screen, and compass-like display screen all appear to be updated about once per second, regardless of the rate at which new track points are added to the “active log”. 

 

The very latest leg of the “breadcrumb trail” on the GPS’s map screen is anchored at one end to the last “active log” track point, and is attached the other end to the moving triangular icon representing the current position of the GPS.  This means that if the GPS is set to record new “active log” track points at a very low rate, the latest leg of the “breadcrumb trail” on the GPS’s map screen will not always offer an accurate depiction of the current direction of travel over the ground.  In this case, the orientation of the triangular icon representing the current position of the GPS will still continue to show the current direction of travel over the ground.

 

As an aside, the Etrex Vista’s pressure-versus-time plot, as opposed to the elevation-versus-time plot or elevation-versus-distance plot, appears to be based upon a separate log that is distinct from the “active logs” that we’ve been discussing here.  This separate log is not cleared when the active log is cleared via the “clear” button on the “tracks” menu.  This separate log is not downloaded to MapSource along with the other “active logs”.

 

The second type of track log generated by the Etrex Vista contains less detail than the “active logs” that we’ve been discussing up to this point.  We’ll call these other track logs the “saved tracks”.   “Saved tracks” have names like “20-JUN-06 02”, or whatever name the user substituted while saving the track. Like “active logs”, “saved tracks” are comprised of many individual “track points”.  For each “saved track” track point, the GPS records only the position, not the date or time.  When a “saved track” is viewed in “MapSource”, each “saved track” track point is displayed along with the altitude, leg length (i.e. distance to the next track point), leg course (which in this context means the direction of travel to the next track point) and position (latitude and longitude).  Since the “saved track” points contain no time or date information the date, clock time, leg time, and leg speed cannot be displayed.

 

A “saved track” only samples a small portion (often 1/5 or less) of the track points that make the corresponding “active logs”.  A new “saved track” begins every time the user presses the “save” button on the “tracks” menu screen.  One “saved track” can cover many days and can sample points from many different “active logs”.  If the user selects the “save all” motion, then the new “saved track” will encompass all the “active logs”, i.e. the new “saved track” will encompass the entire length of the “breadcrumb trail” that appears on the map screen of the GPS.  The GPS will also suggest other shorter intervals such as “save since noon”, etc.  Pressing the “save” button on the “tracks” menu screen to create a new “saved track” has no effect on the amount of memory space left for recording “active logs”.  Pushing the “clear” button on the “tracks” menu screen will erase all the “active logs” and reset the “active log” track log memory indicator to zero, but this will not erase any of the “saved tracks”.  Up to 10 “saved tracks” may be stored in the memory of the Etrex Vista.  The “saved tracks” currently stored in memory are listed on the “tracks” menu page. 

 

When the GPS is saving a “saved track”, the more track points in the corresponding “active logs”, the smaller the fraction of these points that will be incorporated into the “saved track”.  The maximum number of points that can ever be incorporated into a “saved track” is 750. In practical terms, this means that a saving a fresh “saved track” after each flight will capture much more resolution in the “saved track” than will waiting until the “active log” track memory is nearly full after several days of flying and then saving the entire “active log” as a single “saved track”.  Since the active logs can span up to 10,000 track points, and a “saved track” can only include up to 750 track points, the latter course of action would mean that the resulting “saved track” would only capture about 7% of the track points in the corresponding set of “active logs”.

 

When a pilot presses the “save” button on the “tracks” menu screen, creating a “saved track”, and then selects the “show on map” option so that that “saved track” remains visible on the map screen of the GPS, he may notice that there are really two different track lines that lay on top of each other.  One of these lines is the “breadcrumb trail” or “active log”.  This line is usually quite smooth even during tight circling maneuvers.  The other of these lines is the “saved track”, which contains many fewer track points and therefore may be much more “jagged” in appearance than the “active log”, especially during circling maneuvers.  On the Etrex Vista, both the “active logs” and the “saved tracks” are depicted by similar heavy solid lines; the only visible difference between the two is that during circles or curves, the “active log” is smoother and the “saved tracks” are more “jagged”.  As the pilot continues to use the GPS, eventually that portion of the “breadcrumb trail” or “active log” will be overwritten (assuming that the user has selected the “wrap when full” option) and only the coarser “saved track” will remain. 

 

Any given “saved track” will only be visible on the map screen of the Etrex Vista if the “Show on Map” option has been checked on the detailed menu for that track, which can be accessed from the “tracks” menu page.  This box is checked by default when “saved tracks” are downloaded from “MapSource” to the GPS, but not when a new “saved track” is created by using the “save” button on the “tracks” menu screen.

 

Likewise, when GPS data is downloaded to MapSource, a careful examination of the MapSource map screen will reveal that there are often two track lines overlain on top of each other.  Again, the smoother line is the “active log”, and the coarser line is the “saved track”.  (If the user has pressed the “save” button on the “tracks” menu several times, there may be several different “saved tracks” that sample all sample a given “active log”, in which case there will be several different track lines all overlain on top of each other.)  Of course, if the “active log” track memory became full and began to overwrite itself before the GPS data was downloaded to MapSource, then the “active log” for a particular segment of a “saved track” may be absent.  Similarly, if the user has not exercised the “save track” option before downloading the data to MapSource or before a given portion of the “active log” track memory was overwritten, then there may be no “saved track” encompassing a particular “active log”. 

 

Since the “active logs” contain more detail than the “saved tracks”, the only real reasons to use the “save” button on the tracks menu screen to create a “saved track” are to capture some of the corresponding the “active log” points before they are over-written, or to create a single record that encompasses an entire flight (which may include many different “active logs” if the satellite lock was lost and re-acquired several times), or to attach a name to a track for future reference.  However, in Map Source, several “active logs” can be consolidated into a single record, and any name the user desires can be attached to any “active log” or “saved track”.  Therefore if the user is in the habit of downloading the GPS data to a computer at the end of each flight or at the end of each flying day, and is able to capture all of the “active log” track points before any are overwritten, there is no real need to use the “save” button on the tracks menu screen.  On the other hand, if the user does not plan to download the GPS data to a computer very often, or if the user simply doesn’t care to preserve the high level of detail (i.e. the high resolution, and the time and date information) that is characteristic of the “active logs”, then he’ll likely want to use the “save tracks” feature at the end of each flight or at the end of each flying day to capture a subsample of the “active log” track points in the form of a “saved track” before that portion of the “active log” is overwritten.  At this time, it’s often convenient to give a descriptive name to the “saved track” that is being saved, so that when the GPS data is downloaded to MapSource at some later time, it is immediately clear what the various “saved tracks” represent.  (Bear in mind that the individual track log points for the “saved tracks” contain no time or date information.)  As we’ve already noted, saving a fresh “saved track” at the end of each flight will sample a higher fraction of the “active log” track points than will waiting to save a “saved track” when the “active log” memory is nearly full after several days of flying.  Conversely, since the GPS can only hold 10 “saved tracks”, if the goal is to extend the GPS’s memory as far as possible without regard to the level of detail that is captured, the user should set the track log to record very infrequently, and then should wait until the “active log” track memory is nearly full to use the “save tracks” feature to capture a subsample of those “active log” track points in the form of a single “saved track”.  Then the user should clear the “active log” track memory, erasing the “active logs” or “breadcrumb trail”, and repeat the process when the “active log” track memory becomes full again.  With this procedure, the GPS’s memory may be stretched to encompass many days of flying.  However, the user should remember that each “saved track” contains no information as to time or date, other than whatever information the user has included in the title.

 

In actual practice, I make a point of saving a new “saved track” after each flight.  At the end of a day of flying, I download the tracks to a computer, which also captures not only the “saved tracks”, but also all the “active logs”, that are associated with that day of flying.  Then I go through the downloaded “active logs” and “saved tracks” in MapSource and delete any that are of no lasting interest.  Finally I select the “clear track log” option on the “tracks” menu of the GPS, which deletes all the active logs in the GPS’s memory.  This isn’t really necessary, because those active logs would eventually be overwritten with new data, but it prevents me from downloading the same “active logs” to a computer on some later date, which would use unnecessary memory space.  Also, by not keeping old “active logs” in the GPS’s memory, I ensure that should I find myself in the middle of a very long flight, I can easily check to see if the “active log” points corresponding to the beginning of that flight are in any danger of being over-written, and taken action accordingly. 

 

Unfortunately, on the Vista H, the user must use the select the starting and ending points used to create a "saved track". To me this is less convenient than the system used on the older Etrex's and the GPSMap76S, when the user was offered a choice of starting times for the saved track. As a result, I tend to ignore the "save track" feature completely and simply make sure I download my active log before it is overwritten.

 

When multiple “saved tracks” are created on one day, the Etrex Vista will suggest names like “20-JUN-06”, followed by “20-JUN-06 02”, followed by “20-JUN-06 03”, etc.  We’ll call the suffix “02” or “03” in the above example the “sequence number”.  Saved tracks are always assigned the lowest “sequence number” that is available, which means that under certain specific circumstances, the “saved tracks” can end up not being numbered chronologically.  For example if the user does 3 “save track” operations, and then deletes the second “saved track”, and then does one more “save track” operation, the 4th “saved track” will be assigned the now-vacant sequence number of “02” rather than “04”, even though an earlier “saved track” still holds the “03” sequence number.

 

 

20)  Notes on waypoints

 

With the Etrex Vista H, it is fairly easy to create a waypoint in mid-flight.  Simply hold the joystick button down for 2 seconds, and then push the joystick down one more time.  When creating a new waypoint, the user must take care not to move the joystick to the side or several extra steps will be needed.  With each waypoint, the GPS saves the position (latitude and longitude), altitude, and date and time of creation. Unfortunately, at least 4 additional operations are needed to initiate a "goto" function toward the new waypoint! This is very cumbersome and a departure from the system used in the older Etrex's (Vista, etc) and the GPSMap76S.

 

Waypoints are not automatically incorporated as track points in the “active log” or “saved tracks”.

 

On the Etrex Vista H, it is very easy to find the bearing and distance to a waypoint, even if the GPS is not actively navigating toward that waypoint.  Simply call up a list of nearest waypoints (or an alphabetical list of waypoints), and use the joystick to move the cursor over one of them to highlight it.  The GPS will give a continually-updated reading of the bearing and distance to that waypoint.  This could be extremely handy for transmitting a location in an emergency, e.g. when a pilot has deployed his reserve parachute.

 

 

21) List of settings

 

Here is a list of some of the settings I use for my Etrex Vista.  Bear in mind that selecting “500 miles” means that a feature will always be shown and selecting “20 feet” means that a feature will almost never be shown. 

 

I use the 4 numerical data fields on the map screen and/or compass display screen to display "speed", "heading", “glide ratio”, and “glide ratio to destination”, and I use the 2 numerical data fields on the compass-like screen to display “speed” and “heading”. On the trip computer screen I set the 9 numerical data fields to show “speed”, “heading”, “bearing”, “final distance”, “glide ratio”, “glide ratio to destination”, “time of day”, and other variables chosen from “sunrise”, “sunset”, "time of day", or "accuracy of GPS".

 

On the first tab of the “set up map” menu:  orientation “north up”, auto zoom “off”, detail “most”.

On the second tab of the “map setup” menu: saved tracks “500 mi.”, track log  “500 mi.”, track points “100000”, goto line “bearing”. 

On the third tab of the “map setup” menu:  map points "auto",  user waypoints “500 mi.”,  street label "auto",  land cover "auto".

On the sixth tab of the “map setup” menu:  marine colors "off" (except during prolonged flights over some features like state parks, where the “water” display mode seems to give a better view.)

 

On the “setup track log” submenu of the “tracks” menu: “wrap when full” box checked yes, record method “auto”, interval “most often”.

 

On the “heading” submenu of the “setup” menu: display “degrees”, north reference “true”, auto compass switch  1) switch to compass heading when below “0 mph”, 2) use for more than “180 seconds”. These settings ensure that the magnetic compass will stay off.

(Alternate settings for hiking: switch to compass heading when below “10 mph”, 2) use compass heading when below 10mph for more than “5 seconds”.0  These settings allow the user to toggle the magnetic compass on and off at will, with the upper right button, while travelling on foot. The magnetic compass is convenient because it makes for a more stable display of "heading" while travelling at low speeds, so long as the GPS unit is held roughly level, but the magnetic compass also increases the drain on the batteries.

 

On the “system” submenu of the “setup” menu: GPS “normal” or "battery saver", WAAS “enabled”, altimeter auto calibration “off” (or occasionally “on” for operation in areas where I can’t set the altimeter to match a known reference altitude; also set auto calibration "on" for all non-flying applications.)

 

On the “units” submenu of the “setup” menu: position format “degrees, minutes, decimal minutes”, map datum “WGS 84”

 

 

22) Additional notes on track logs: uploading “active logs” and “saved tracks” from MapSource 6.9.1 to the Etrex Vista

 

As noted above, when GPS data is downloaded to MapSource, the “active logs” as well as the “saved tracks” appear on MapSource’s “tracks” page.  The “active logs” have names like “ACTIVE LOG”, “ACTIVE LOG 001”, “ACTIVE LOG 002”, etc.  The “saved tracks” have names like “20-JUN-06 02”, or whatever name the user substituted while saving the track.  In MapSource, the user can re-name any “active log” or “saved track”.  In MapSource, several different “active logs”  and/or “saved tracks” can be joined together into one single “active log” or “saved track”.

 

In MapSource, the user can also select a specific “active log” or “saved track” to display as a track on the map or as an altitude-versus-distance plot.  MapSource cannot display an altitude-versus-time plot. 

 

In MapSource, parts of “active logs” (including the time and date information) can be spliced into “saved tracks” (which lack time data), and vice versa.  The actual position data for individual track log points cannot be changed, but track points can be deleted.  This will create a change in the leg length and leg course values displayed for the preceding track point, as well as the leg time and leg speed values (if present.).  Note that now the distinction between “active logs” and “saved tracks” is starting to blur—once we start to manipulate tracks in MapSource, splicing pieces of “saved tracks” into “active logs” or vice versa, we no longer can categorize a track segment as a “saved track” or an “active log” depending on whether time and date information is present or not. 

 

In fact as far as MapSource is concerned, there is no distinction at all between an “active log” and a “saved track”.  However, as data is uploaded from MapSource to the Etrex Vista, the GPS will treat the data differently depending upon whether it recognizes the segment as an “active log” or as a “saved track”.

 

When data is uploaded from MapSource to the Etrex Vista, any segment whose name begins with the words “active log” (not case-sensitive) is treated as an “active log”, and any segment whose name does not begin with the words “active log” is treated as a “saved track”.  This is true even if the “active log” was originally a “saved track” whose name has been changed to begin with the words “active log”, or vice versa.  This is also true even if the “active log” has had bits of “saved tracks” spliced into it, or vice versa.  So the ultimate definition of an “active log” is any track segment whose name begins with the phrase “active log” (not case-sensitive), and the ultimate definition of a “saved track” is any track segment whose name does not begin with the phrase “active log”.  To take a rather complicated example, if the user goes into the “saved tracks” menu screen of the Etrex Vista and changes the name of one of the “saved tracks” to “ACTIVE LOG”, and then downloads that track segment to “MapSource”, then if that segment is ever uploaded back to the Etrex Vista, the uploaded segment will be treated as an “active log” rather than a “saved track”!

 

In addition to the limit of 10,000 total “active log” track points that can be stored in the memory of the Etrex Vista, there may be a limit to the total size of any one “active log” that can be uploaded successfully from MapSource to the Etrex Vista, but I’ve not encountered this limit in actual practice.

 

As an “active log” is uploaded from MapSource, its name will not appear on the “saved tracks” screen, but the “tracks log” memory indicator will show an increase in the amount of memory that is currently in use, and the segment will appear on the “plot versus distance” page of the elevation screen, and the segment will be visible in the “breadcrumb trail” that represents the cumulative total of all the “active logs” in memory.  This is all characteristic of the way that the Etrex Vista treats any “active log”.  The time-related and date-related data normally present in an “active log” are preserved when the “active log” is uploaded from MapSource to the Etrex Vista.  As an “active log” (e.g. “ACTIVE LOG 004” or “active log great flight June 6”) is uploaded from MapSource to the GPS, its name will be automatically modified to the standard “active log” format of the words “ACTIVE LOG” followed by three numbers (e.g. perhaps becoming “ACTIVE LOG 041”), and these three numbers will be consecutive to the numbers of all the other “active logs” currently in memory.  The “active logs” in memory are normally numbered from oldest to newest (e.g. “ACTIVE LOG” followed by “ACTIVE LOG 001” followed by “ACTIVE LOG 002”, where “ACTIVE LOG” is the oldest and “ACTIVE LOG 002” is the newest), but when an older “active log” is uploaded from MapSource to the Etrex Vista, it will receive a number consecutive to all the other “active logs” in memory at that moment, even if it actually represents a much older track segment.  On the “plot versus distance” version of the “elevation” screen, from left to right, the “active logs” with the lowest numbers are illustrated first, followed by the “active logs” with the highest numbers (e.g. “ACTIVE LOG”, followed by “ACTIVE LOG 001”, followed by “ACTIVE LOG 002”, etc.)  When all the “active logs” have been generated internally by the GPS, this means that the “plot versus distance” and “plot versus time” elevation screens will run in chronological order (oldest to newest) from left to right, but when “active logs” have been uploaded from MapSource, this is no longer the case, since a newly uploaded track will appear on the right side of the “plot versus distance” and “plot versus time” elevation screens, even if it represents very old data.  If the same “active log” is uploaded multiple times from MapSource, it will appear multiple times on the “plot versus distance” and “plot versus time” elevation screens.  All in all, the Etrex Vista is not really designed to deal well with “active logs” that are uploaded from MapSource to the GPS.  In fact, when “active logs” are uploaded from MapSource to the GPS in a non-chronological order, and then viewed with the GPS’s “plot versus time” elevation screen, sometimes this causes the GPS to crash.  (When I’ve experienced this, I’ve always been able to restart the GPS with no problems, and with no lost data.)     For the best chance of trouble-free operation, the best policy may be to use the “clear” option after uploading data from MapSource to the GPS, so that none of the “active log” segments that might have been uploaded from MapSource will linger in the active log memory area.  (If desired, the “save” menu option can first be used to save these “active log” segments as “saved tracks”, and then the “clear” menu option can be used to empty the “active log” memory area.)  However, as of this writing, I’ve never had any problems that seemed to be related to “active logs” that were loaded from MapSource to the GPS in a non-chronological order, except while I was actively scrolling the “plot versus time” version of the elevation screen. Therefore I don’t think that this problem would arise during flight.

 

We’ve noted that when data is uploaded from MapSource to the Etrex Vista, any segment that does not begin with the name “active log” (not case-sensitive) is uploaded as a “saved track” rather than an “active log”.  As a “saved track” is uploaded, its name will appear on the “saved tracks” screen, and the “tracks log” memory indicator will not show an increase in the amount of the “tracks log” memory that is currently in use. The segment will not appear on the “plot versus distance” or “plot versus time” page of the elevation screen.  The segment will not be visible in the “breadcrumb trail” that represents the cumulative total of all the “active logs” in memory.  All this is characteristic of how the Etrex Vista handles any “saved track”, regardless of whether it is created internally by the GPS or uploaded from MapSource.  Like all other “saved tracks”, the uploaded ”saved track” will not contain any time-related or date-related information, even if time-related and date-related information was present when the segment resided in MapSource.  (This situation could arise if the segment was originally an “active log”, whose name was then changed so that it no longer began with the words “active log”, which would then turn the segment into a “saved track” as far as the Etrex Vista is concerned.)   The Etrex Vista handles “saved tracks” uploaded from MapSource without any problems, just as if they had been generated internally rather than uploaded.  If the name of the “saved track” was longer than 13 characters when it resided it MapSource, it will be truncated at 13 characters after transfer to the Etrex Vista, and lower case letters in the name will be converted to capital letters.

 

We’ve mentioned that the maximum number of points can be incorporated into a “saved track” is 750.  If the user attempts to upload a longer “saved track” from MapSource to the GPS, a “track truncated” message will appear on the screen of the GPS after the first 750 points are transferred.  However, “active logs” can be much longer than 750 points.  If the user wants to transfer a “saved track” that is longer than 750 points (perhaps because it has been made from several “saved tracks” that have been spliced together in MapSource) from MapSource to the GPS, here’s a handy trick.  First, “clear” the GPS’s “active log” memory by using the “clear” button on the “tracks” menu screen.  Then in MapSource, change the name of the segment of interest from the “saved track” format to the “active log” format (e.g. simply “active log”.)  Then transfer the segment over to the GPS.  Naturally, the segment will transfer as an “active log” rather than a “saved track”.  Once the segment has been transferred to the “active log” memory of the GPS, press the “save” option on the GPS’s “tracks” menu screen to create a “saved track”.  Choose the “save entire log” option.  The resulting “saved track” will represent a subsample of the track points from the newly transferred “active log”, and though the full length of the segment will be present with no truncation at the end, the segment will be comprised of no more than 750 track points.  As noted above, it might be wise to use the “save” option to clear the “active log” memory area again at the end of this procedure.

 

 

23) Additional notes on MapSource 6.9.1

 

We’ve referred to MapSource frequently above.  In all cases the specific version of interest was MapSource 6.9.1. 

 

I now always save MapSource files as “Garmin GPS Database Version 2 (*.gdb)”, which is the latest file version offered by MapSource 6.9.1.  I’m not familiar with the differences between files of this type, and the two earlier file versions also offered as “save” options by MapSource 6.9.1.  These 2 earlier file versions are “Garmin GPS Database Version 1 (*.gdb)”, and “MPS Files (*.mps)”.  I used the *.mps file version in the past with an older version of MapSource, and haven’t had any problems re-saving these older files as the newer Version 2 (*.gdb) files, nor have I noticed that this has created any changes in the files. 

 

Here are a few additional tips on the MapSource program:

 

When data is being transferred from a GPS to the MapSource computer program, and the computer involved is running on an external power supply rather than on internal batteries, a momentary interruption of power to the computer will cause the transfer to fail.  Before resuming the transfer, the GPS should be turned off and then back on; otherwise the subsequent transfer will also fail.  When there is a high risk that the computer’s power supply will be momentarily interrupted (e.g. when running off an inverter in a car) it’s often best to disconnect the power supply before beginning the transfer of data. 

 

When viewing downloaded GPS data in MapSource, if the file contains a large number of waypoints, the identifying labels for the waypoints may obscure most of the other information on the map screen, including the downloaded tracks.  An easy way to make all the waypoints disappear is to go to the box labeled “show waypoints in category...”, and enter a category for which there are no waypoints (e.g. “Category 16”.)

 

In MapSource, if you right-click on a track or waypoint or route on the left side of the screen, that feature will be highlighted in yellow on the map.  However, that feature may lie beyond the borders of the map, in which case it will not be visible.  If you go to the left side of the screen and left-click on a waypoint or track or route, or a group of multiple waypoints or multiple tracks or multiple routes, and then choose the “show on map” option, the map will automatically switch to a view that is centered around the selected features, and will automatically change to a scale that will show all the selected features in their entirety.  The same thing happens when you select the “show on map” button on the “track properties” screen or the “waypoint properties” screen.

 

On MapSource’s map screen, if you place the arrow pointer on particular track segment, and then right-click on that point, and then select the “track properties” option, the “track properties” screen will appear.  The “track properties” screen is a list of every track point in a given track.  The track segment on which you’ve right-clicked will be highlighted on the “track properties” screen.  This is a handy way to find the altitude or lat/lon associated with a given point on a track.  If available—i.e. if the track originated as an “active log” rather than a “saved track”—the “track properties” screen will also show the speed at that particular point in the track.

 

On MapSource’s “track properties” screen, if you click on a particular track point or group of track points, that track point or group of track points will be highlighted on the map screen.  (As long as the “track properties” screen is open, unfortunately you won’t be able to manipulate any other screens, but you can move the “track properties” screen to one side to get a view of the other screens.)  If the “center map on selected item(s)” box is checked, the map will move to center around the selected items.  If you click on the “show on map” button on the “track properties” screen, the map screen will automatically change to a scale that shows the entire track that is being featured on the “track properties” screen.  This is not always desirable—avoid clicking on the “show on map” button on the track properties screen if you want to keep the map zoomed in to scale that is too large to show the entire track in question.  When you click on a particular track point on the “track properties” screen, sometimes the highlighted track point will be lost amidst the clutter on the map.  Choosing the “center map on selecting item(s)” box and then zooming the map in will reveal the highlighted track point.  However, you’ll have to close the “track properties” screen before you can zoom the map in.  After zooming the map in, you can easily bring up the “track properties” screen again, as described above.

 

As noted above, often several tracks will lie on top of each other.  Typically one will originate from an “active log” and one or more others will originate from a “saved track”.  In this case it can be helpful to make a copy of the MapSource file and delete all the “saved tracks” from that copy, so that only the “active logs” remain.  This allows you to easily click on a track and bring up the “track properties” screen for the associated “active log”, rather than accidentally bringing up the “track properties” screen for a “saved track”, which contains less information (fewer track points and no time, date, or speed information.)

 

On MapSource’s “track properties” screen, the “show profile” button brings up a graph of altitude versus time.  There’s no easy way to pick a point on this altitude profile and highlight it on the “track properties” screen or on the map.  By scanning through the altitude information on the “track properties”, it’s possible to find the track points associated with altitude peaks, and then locate these points on the map.

 

In MapSource, individual waypoints or sets of waypoints can be cut, copied, or pasted from one file to another.  One very handy feature is the ability to select waypoints or tracks or routes or maps with the pointer tool on the map, rather than from the alphabetical lists of waypoints, tracks, and routes.  To do this, first make sure that the desired category (maps, waypoints, routes, or tracks) is “on top” of the other categories on the left side of the screen.  Then click on the pointer tool (the icon looks like an arrow), and draw a box around the area of interest on the map. All the waypoints, routes, and tracks in the area of interest will be highlighted in yellow on the map.  (More precisely, the entire length of all the routes and tracks that pass though the area of interest will be highlighted in yellow on the map, along with all the waypoints that lie in the area of interest.)  Then go to the left side of the screen.  You can left-click on the “up” and “down” arrows to scroll up or down through the list of whichever feature is “on top” (waypoints, routes, or tracks), but don’t try to click on the index tabs to change which feature is on top, or you’ll have to start over.  We’ll assume now that “waypoints” are on top; if “routes” or “tracks” are “on top” a similar procedure will apply.  When you find one of the waypoints that lies within the block of area that you’ve outlined on the map, it will be highlighted in light purple.  All the other waypoints that lie within the box you’ve outlined on the map are also highlighted in purple, though they may not be all visible at once on the left side of the screen.  On the left side of the screen, right-click on any of these highlighted waypoints (being careful not to accidentally click on any waypoint that is not highlighted) and you’ll get a menu of options that includes “cut”, “copy”, “paste”, and “delete”.  Whichever option you choose will be applied to all the highlighted waypoints, i.e. to all the waypoints that lie within the block that you’ve outlined on the map.  This is a very good way to quickly choose all the waypoints that lie within one particular geographic region.

 

 

24) Additional links

 

For more GPS-related information, see the following articles on the Aeroexperiments website:

 

"Using a GPS in soaring flight"

 

"Notes on the glide ratio functions of some Garmin GPS receivers with pressure sensors, including the GPSmap 76S/CS/CSX, GPSmap 60CS/CSX, and Etrex Vista/Vista C/Cx"

 

“Map screen size comparison of some handheld Garmin GPS units with numerical data fields enabled: GPSmap 76S, GPSmap 76C series, GPSmap 60 series, and Etrex series”

 

"Notes on the Garmin GPSmap 76S"

 

"Notes on the Garmin Etrex Vista"

 

 

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