::Aero-Experiments::

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. 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.

In this article, we’ll use the phrase “GPS” as shorthand for a GPS receiver, along with the associated display screen, etc.

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

Note that Etrex Vista is quite different than the newer Etrex Vista C/Cx, which has a slightly different shape and screen size, as well as a color display. Unless we state otherwise, when we speak of the Vista we’ll be referring only to the older version, not the Vista C/Cx. When we refer to “the older Etrex series”, we mean the Etrex Venture, Legend, Vista, etc, as contrasted to the newer “C” or “Cx” versions of these products, which have the newer, modified shape and screen size. On the other hand, when we speak of “the Etrex series” or “the entire Etrex series”, we’ll include the newer C/Cx versions as well as the older versions.

As a point of comparison, readers might also be interested in reading more about the GPSmap 76S—see the related article on this website entitled "More on the Garmin GPSmap 76S”.

2) Ergonomics

All the Etrex series GPS’s are very compact and fit easily in the hand. The side-mounted buttons are easy to reach with the fingers and thumb of the same hand that is holding the GPS. Since the Etrex series GPS's are well suited to single-handed operation, they are well suited for use in a vehicle where no mount is available (e.g. a rented or club-owned sailplane or airplane). In an airplane, it is often convenient for the pilot to hold the GPS in the same hand that is holding the control yoke, and in a sailplane, the pilot can hold the GPS in his free hand as it rests upon the canopy sill. Since the Etrex series GPS's are so compact, they are ideal for use while hiking, backpacking, etc., and would be a great choice for anyone planning to use their GPS in this kind of activity as well as in flight.

The side-mounted buttons of the Etrex series are not particularly well-suited for operation when the GPS is attached to a mount. This is especially true if the user is wearing gloves, or if other instruments are mounted close alongside the GPS, restricting access to the side-mounted buttons. In some operations like creating a new waypoint, the user is required to push straight down on the joystick and hold it in that position for about 2 seconds without moving it to the side, and this too can be a bit difficult with gloved hands. Nonetheless, I’ve gotten a great deal of useful service out of my Etrex Vista, mounted to a down tube of my hang glider.

3) 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 3 different Etrex series GPS’s, and all eventually sported lots of duct tape to hold this damaged rubber strip firmly in place.

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. This problem can occur regardless of whether the GPS is running on batteries or on external power. A gentle knock on the side of the GPS will temporarily cure this problem--perhaps there is some kind of delamination within the display screen.

4) Notes on the map screen size

Naturally, the map screen of the Etrex series is smaller than the map screen of many other GPS’s. There is only room for 2 numerical data fields, plus the "navigation status" field, on the map screen or the heading display screen. Compare this to the GPSmap 76S, which has a much larger map screen with room for 9 small numerical data fields. (The GPSmap 76S is fairly unique in this respect, even compared to the newer GPSmap 76C/Cx/CS/CSx and GPSmap 60/60C/Cx/CS/CSx.) Comparing the taller, narrower screen of the older Etrex series (Legend, Vista etc) with the shorter, wider screen of the newer Etrex series GPS’s (Legend C/Cx, Vista C/Cx etc): when 0 or 2 numerical data fields are displayed, the newer Etrex’s have more screen area remaining for the map display than do the older Etrex’s. But when more than 2 numerical data fields are displayed (e.g. 2 numerical data fields plus the “navigation status” screen on the Vista, or 4 numerical data fields on the Vista Cx), the older Etrex’s have more screen area remaining for the map display than do the newer Etrex’s. For more, see the related article on this website entitled “Map screen size comparison of some handheld Garmin GPS units with numerical data fields enabled”.

5) 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 situations. I never use the elevation screen in flight. The numerical data page can display 8 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 2 numerical fields on the map screen to show “glide ratio” and “glide ratio to destination”, and I usually configure the 2 numerical data fields on the heading display screen to show “heading” and “speed”, and I usually configure the numerical data page to include all these values plus “bearing”, “distance” “time of day”, and “sunrise” or “sunset”. Since there isn’t room to display all the numerical data fields that interest me on the map screen, I do find that I tend to page back and forth between the different display screens much more often when flying with the Etrex Vista than when flying with the GPSmap 76S. As noted above, when I’m holding the unit in my hand in an airplane or sailplane this is easy to do, but when the unit is mounted to the down tube of my hang glider and I’m wearing gloves, it’s a bit awkward to operate the buttons that change the display screens.

6) Notes on mounting and antenna performance

The Etrex series uses a patch antenna while the GPSmap 76 and 60 series all utilize a quad-helix antenna. No external antenna is available for the Etrex series. In cars, buildings, aircraft, etc I’ve often found that my Etrex Vista performs just as well as my GPSmap 76 (with no external antenna), in terms of satellite reception. I’ve generally had acceptable results using the Vista with no external antenna inside of 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. It is the case that the patch antenna is directionally sensitive, and performs best when the GPS is laying flat on its back. In situations where the GPS will be mounted on its side, the patch antenna does not perform as well as a quad-helix antenna would. 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 I need 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".

7) Some pros and cons of the Garmin Etrex Vista compared with the GPSmap 76S

In addition to the issues relating to ergonomics, screen size, and antenna orientation described above, here are some other pros and cons of the Etrex Vista in comparison to the GPSmap 76S. Note that unless specifically stated otherwise, we are not including the Vista C or Cx, or the GPSmap 76C/Cx/CS/CSx, in our comparison here.

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

* On the entire Etrex series (including the newer "C" and "Cx" models), as well as the GPSmap 76C/Cx/CS/CSx and the GPS60C/Cx/CS/CSx, the alphanumeric “virtual keyboard” makes it easy to quickly enter waypoint names. The GPSmap 76S lacks this alphanumeric “virtual keyboard”.

* On the entire Etrex series (including the newer "C" and "Cx" models), as well as the GPSmap 76C/Cx/CS/CSx and the GPS60C/Cx/CS/CSx, it is very easy to find the bearing-and-range to a 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 that waypoint. The GPSmap76S cannot show the bearing and distance to a waypoint unless the GPS is actively navigating toward that waypoint.

* On the older Etrex series GPS’s, the “navigation status” field on the map screen displays the name of the target waypoint, the distance to the target waypoint, and the ETE to the target waypoint. The GPSmap 76, the GPSmap76C/Cx/CS/CSx, the GPS60C/Cx/CS/CSx, and the newer "C" and "Cx" Etrex series GPS's Etrex series GPS's all lack a “navigation status” field of this type, and all lack the capability to display the “ETE”, though the ETA and the distance to the target waypoint can be displayed in one of the numerical data fields on the map screen or elsewhere.

* On the entire Etrex series (including the newer "C" and "Cx" 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 could be useful while flying a powered aircraft along airways or other defined routes, but is of no value during soaring flight. 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 "C" and "Cx" 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 "C" and "Cx" 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.

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

* Significantly more operations (pressing a button, moving the joystick, etc) are needed to activate a “goto” function toward the nearest waypoint (15, compared to 6), or to pan the map (4, compared to 1). 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.

* No tide-related features

* Date and time of creation of each waypoint is not saved

8) Some pros and cons of the Garmin Etrex Vista compared with the Etrex Vista C/Cx

Some “pros” of the Etrex Vista in comparison to the Etrex Vista C/Cx:

* As noted above, when more than 2 numerical data fields are displayed (e.g. 2 numerical data fields plus the “navigation status” screen on the Vista, or 4 numerical data fields on the Vista Cx), the older Etrex’s (Vista etc) have more screen area remaining for the map display than do the newer Etrex’s (Vista C/Cx etc).

* On the older Etrex series GPS’s, the “navigation status” field on the map screen displays the name of the target waypoint, the distance to the target waypoint, and the ETE to the target waypoint. The GPSmap 76, the GPSmap76C/Cx/CS/CSx, the GPS60C/Cx/CS/CSx, and the Etrex Legend C/Cx/Vista C/Cx all lack a “navigation status” field of this type, and all lack the capability to display the “ETE”, though the ETA and the distance to the target waypoint can be displayed in one of the numerical data fields on the map screen or elsewhere.

Some “pros” of the Etrex Vista C/Cx in comparison to the Etrex Vista

* As noted above, when 0 or 2 numerical data fields are displayed, the newer Etrex’s (Vista C/Cx etc) have more screen area remaining for the map display than do the older Etrex’s (Vista etc).

* Color screen

* USB data port

* Removable SD memory cards (“Cx” units only)

* Much easier to "pan" the map screen.

* The GPS’s present location can be averaged over time, to increase accuracy when marking a new waypoint when the GPS is stationary

9) “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.

10) 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, 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: “Auto compass switch. Use GPS heading when exceeding (X). Use compass heading when below (X) for more than (Y).” (The letters “X” and “Y” do not actually appear in the text.) 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 ensure that the magnetic compass stayed on, 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. Note that these conditions would not be adequate to ensure that the compass stayed on during flight in a light airplane, as the speed would often be greater than 99 mph. However, there is no reason to use the magnetic compass feature during flight in a light airplane.

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 displayed on the “system” submenu of the “setup” menu. The user can change the position of this toggle simply by clicking on it. There is another way to change the position of this toggle without going into the setup menu at all: if the user simply holds the upper right button down for two seconds, the position of the “compass toggle” will flip from “off” to “on” or vice versa, and a message will appear on the screen. This message can be slightly misleading: if the position of the compass toggle has been flipped from “off” to “on”, a message will appear on the screen that implies that the magnetic compass has in fact been activated, but in reality the magnetic compass will not be activated unless the time-speed interlock has also been satisfied. The practical ramification of all this is as follows—if while scrolling through the various features, the user sees an unwanted message saying “compass on” or “compass off”, it means that he has accidentally changed the position of the “compass toggle” by holding down the “page” button for several seconds. He can ignore this message, or he can quickly put the “compass toggle” back to its original position by holding down the upper right button for several more seconds. One consequence of allowing the “compass toggle” to remain in the “on” position during flight is that after landing, when the time-speed interlock is no longer satisfied because the GPS unit is no longer in motion, the magnetic compass will turn on, creating an unwanted drain on the batteries. . When the compass toggle is in the “on” position, this also causes the compass to be active whenever the GPS unit has lost the satellite lock, as well as during the initial start-up phase when the GPS unit has not yet acquired a satellite lock, regardless of how the time-speed interlock parameters have been set. Again, this could create an unwanted drain on the batteries.

As long as the user doesn’t intentionally or accidentally switch the compass toggle to the “on” position by holding down the “page” button for several seconds, the magnetic compass sensor will stay off at all times, regardless of any other factors.

If the GPS unit is being used for hiking or other applications where the magnetic compass feature might be occasionally wanted, the user should set the time-speed interlock parameters in such a way that they are easily satisfied (e.g. “X” = 99mph, “Y” = 5 seconds). The user can save battery power by leaving the compass toggle “off” most of the time. Holding the upper right button down for a few seconds to switch the compass toggle back to the “on” position is an easy way to switch the compass “on” when it is needed (and then back off again when it is no longer needed), as long as the time-speed interlock has been set appropriately.

Whenever the magnetic compass sensor is actually active, a small compass icon will be displayed at the very top of the map display screen and heading display screen.

11) “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, 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, 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.

12) “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 C/CX, 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 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.

13) “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.

14) “Battery saver” mode

When the GPS is set to "battery saver", the "battery saver" mode becomes active when the GPS has been stationary or has been moving at a nearly constant speed and direction for a certain time period, which appears to be somewhere between 10 and 30 seconds. Therefore the "battery saver" mode reduces battery consumption when an aircraft is stationary on the ground before take-off. I suspect that the "battery saver" mode rarely becomes active during soaring flight. Therefore I suspect that setting the GPS to "battery saver" does not extend the battery life very much during soaring flight. By the same token, I suspect that setting the GPS to "battery saver" will only rarely cause a noticeable decrease in the responsiveness of the GPS during soaring flight. I suspect that the battery saver mode will not become active during most situations when a pilot desires maximum accuracy from his GPS, such as when checking the wind velocity by allowing the aircraft's heading to slowly change and noting the groundspeed. It appears that the "battery saver" mode does not become active when an external power cord is attached to the GPS. During side-by-side comparisons, I've noticed that the "battery saver" mode on my Etrex Vista becomes active much less often than does the "battery saver" mode on my Etrex Legend. This may indicate that on pressure-sensor equipped Garmin GPS's, the "battery saver" mode does not become active when the elevation or rate of climb is changing.

15) 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. 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, 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 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.

When the “save tracks” option is used to create a “saved track”, the user is often presented with a choice of two different starting times that are only one minute apart. Often these correspond to the last time that the GPS was switched on, and the time the GPS acquired a satellite lock after being switched on. By selecting the later of these two times as the starting time for the saved track, the user can often avoid incorporating erroneous points that were associated with some previous position. This isn’t very important, but it does prevent the “distance versus altitude” plot for the “saved track” from having a large flat stretch at the start, representing the distance between the previous location that the GPS was used, and the actual location where the GPS was last switched on.

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.

16) Notes on waypoints

With the Etrex Vista, 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.

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

Unlike some other Garmin GPS’s such as the GPSmap 76S, the Etrex Vista does not save the date and time of creation of each waypoint.

On the Etrex Vista, 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.

17) 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 2 numerical data fields on the map screen to display “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 8 numerical data fields to show “speed”, “heading”, “bearing”, “final distance”, “glide ratio”, “glide ratio to destination”, “time of day”, and “sunrise” or “sunset”.

On the first tab of the “set up map” menu: orientation “north up”, auto zoom “off”, detail “most”, lock on road “off”, display mode “land” (except during prolonged flights over some features like state parks, where the “water” display mode seems to give a better view.)

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: waypoints “500 mi.”

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) use GPS heading when exceeding “0 mph”, 2) use compass heading when below 0mph for more than “180 seconds”.

On the “interface” submenu of the “setup” menu: serial data format “NMEA” for connection to my variometer, “Garmin” for downloading data to a computer with MapSource or uploading data from MapSource.

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

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

18) 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.

19) 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.