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GliderSK (Garmin ConnectIQ) App
Usage instructions
Always follow official or recommended procedures to insure flight safety,
*independently* from the help this application can offer.
In particular, this application relies on barometric pressure to derive
GliderSK relies on your device's raw barometric sensor to compute the altitude,
using the ad-hoc International Civil Aviation Organization (ICAO) formulas and
according to the International Standard Atmosphere (ISA).
Consequently, you MUST calibrate GliderSK internal altimeter - using either
the known QNH or elevation (see Settings below) - to obtain an accurate
altitude reading (the device's "native" altimeter/barometer settings are
Global View
The GliderSK Global view displays all the flight data in a single view, without
any further bells or whistles:
- Top-Left:
your current acceleration (G-meter)
- Top-Right:
your current rate-of-turn
- Left:
your current altitude
- Center:
your current finesse
- Right:
your current (GPS) heading
- Bottom-Left:
your current vertical speed
- Bottom-Right:
your current ground speed
Safety View
The GliderSK Safety view works by continuously calculating the height (Above
Ground Level) that would be reached at your destination, using a two-pass
- Pass 1 / Estimation: worst-case finesse and best-case heading
the height at destination is estimated using your actual ground
speed (as if heading straight towards that destination) and the
user-specified reference finesse (or the actual finesse if is lower
than that).
- Pass 2 / Alert: actual (or worst-case) finesse and heading
IF the resulting height (Above Ground Level) is below or equal to
the user-specified decision height, the height at destination is
calculated again, using the *actual* finesse (unless you're ascending,
in which case the user-specified reference finesse is used) and
the *actual* speed-towards-destination (which accounts for heading
vs bearing discrepancies).
Once the estimated or actual height at destination have been computed, alerts
will be issued according to the corresponding height:
- Critical Alert: red background / high-frequency tone
when the height is below or equal to the user-specified critical height
- Warning Alert: yellow background / low-frequency tone
when the height is below or equal to the user-specified warning height
The GliderSK Safety view displays all critical flight safety information in a
single view, using visually appealing alert colors:
- Top-Left:
the name of your current destination
/ OR /
the elevation of your current destination
/ OR /
the bearing of your current destination
- Top-Right:
the distance to your current destination
- Left:
your current altitude
- Center:
your current finesse
/ OR (if in ascent) /
your reference finesse (grayed-out)
- Right:
the actual height when reaching your current destination
/ OR (if the corresponding height is above your decision height) /
the estimated height when reaching your current destination (grayed-out)
- Bottom-Left:
your current vertical speed
- Bottom-Right:
your current ground speed
/ OR /
your current speed towards your current destination
Both Left and Right (altitude/height) fields will have their background:
- RED if the corresponding height is below the critical height
- YELLOW if is below or equal the warning height
- GREEN otherwise.
The Center (finesse) field will have its background:
- RED if the actual finesse is below or equal to the reference finesse
- YELLOW if the actual finesse is above the reference finesse
- GREEN if in ascent (and the reference finesse is used for calculation)
In case the positioning quality gets below Usable, all fields will turn RED.
If a reasonable "last known" position is available, values will still be displayed
(all grayed-out), otherwise no value will be displayed.
By pressing the MENU button (long-pressing the UP button) a first time, the
application will display the current safety-critical settings:
- Top-Left:
the name of your current destination
- Top-Right:
the elevation of your current destination
- Left:
your chosen critical height
- Center
your chosen reference finesse
- Right:
your chosen warning height
- Bottom-Left:
your chosen decision height
- Bottom-Right:
your chosen time constant
Then, by pressing the SELECT button, the application will toggle the display and
choice if the Top-Left and Bottom-Right fields. Note than whenever the Safety
View is in the Pass 2 / Alert mode, those fields will always show, respectively,
the bearing and speed towards your current destination.
By pressing the MENU button (long-pressing the UP button) a second time, you will
enter the Safety destination selection menu (and access to the Settings menu):
- Load Destination:
load your current destination from the destination memory, ordered
by distance if your location is available
- Edit Destination:
edit the name, latitude, longitude and elevation of your current
destination OR pick your current location/elevation as destination
- Save Destination:
save your current destination to the destination memory (100 slots available)
- Delete Destination:
delete a destination from the destination memory
- Safety:
safety-specific settings (see Settings below)
- Settings:
all settings (see Settings below)
Rate-of-Turn View
The GliderSK Rate-of-Turn displays your current rate-of-turn both textually
and graphically, using visually appealing colors:
- GREEN for right (starboard) turns
- RED for left (port) turns
Variometer View
The GliderSK Variometer displays your current ascent/descent rate both textu-
ally and graphically, using visually appealing colors:
- GREEN for ascent
- RED for descent
Varioplot View
The GliderSK Varioplot graphically displays you ascent/descent rate along your
flight path, using visually appealing colors ranging from:
- (Bright) GREEN for maximum ascent rate
- (Bright) RED for maximum descent rate
In addition, the following values will be displayed in the corner of the plot:
- Top-Left:
your current altitude
- Top-Right:
your current vertical speed
- Bottom-Left:
your current ground speed
- Bottom-Right:
your current finesse
By pressing the MENU button (long-pressing the UP button), you will enter the
Pan/Zoom mode, where short pressing the following buttons will result in:
- SELECT: switch between zoom in/out, pan up/down, pan left/right
- UP: zoom in /OR/ pan up /OR/ pan left
- DOWN: zoom out /OR/ pan down /OR/ pan right
By pressing the MENU button (long-pressing the UP button) a second time, you
will enter the Settings menu (see Settings below).
Timers View
The GliderSK Timers view displays the start and elapsed times since:
- the activity (application) was started
- the (last) recording was started (see Activity Recording below)
- the last recording lap
Activity Recording
Controlling your activity recording status (start, pause, resume, save, discard)
is achieved by pressing the SELECT button. When recording, the BACK key will act
as Lap Key (unless configured not to do so; see Settings below).
GliderSK adds custom fields to the recorded FIT file:
- Barometric Altitude
- Vertical Speed
- Rate-of-Turn
- Acceleration
(which will be plotted in Garmin Connect IF your installed the application
through the Garmin ConnectIQ store)
Unless explicitely stated otherwise for a given view, you may enter the Settings
menu by pressing the MENU button (long-pressing the UP button).
The application allows you to specify the following settings:
* Altimeter
> Calibration
- QNH:
calibrate the altimeter using the current known QNH
- Elevation:
calibrate the altimeter using the current known elevation
(QNH shall be adjusted accordingly)
> Correction
- Absolute:
set the absolute device's sensor error correction
- Relative:
set the relative device's sensor error correction
* Variometer
- Range:
the range used for the variometer display and tones (3.0, 6.0 or 9.0 m/s)
- Mode:
whether the variometer tracks altitude variation only (dAlt) or compensates
for cinetic energy (speed) variations (dE)
- Energy Efficiency:
percentage of the short-term cinetic energy (speed) variations that may be
recovered as potential energy (altitude)
- Plot Range:
the time range (in minutes) for plotting the variometer-vs-location history
* Safety
- Finesse:
the finesse to apply for height estimation (when in ascent)
- Decision Height:
the height (Above Ground Level) under which to switch from height
estimation (using worst-case finesse and best-case heading) to
actual height calculation (using actual finesse and heading)
- Warning Height:
the height (Above Ground Level) under which to issue warning alerts
- Critical Height:
the height (Above Ground Level) under which to issue critical alerts
- Heading Bug:
whether to always hide the heading bug (off), always show it (on) or only
in Pass 2 / Alert mode (auto)
* Sounds
- Variometer Tones:
whether to play variometer tones
- Safety Tones:
whether to play alert tones when below warning or critical height
(or GPS signal is lost)
- Mute distance:
the distance (from destination) under which to mute all sounds
(and let you concentrate on your take-off or landing)
* General
- Time Constant:
time constant/window (in seconds) used for averaging (SMA) sensor values
- Display Filter:
whether to display instantaneous or filtered data (see Data Filtering below)
- Background Color:
the background color (black or white)
- Lap Key:
whether the BACK key adds a new lap to a recording activity
* Units
- Distance Unit:
preferred units for displaying distance (and horizontal speed) values
- Elevation Unit:
preferred units for displaying elevation (and vertical speed) values
- Rate-of-Turn Unit:
your preferred unit for displaying rate-of-turn values
- Timezone:
display Local Time (LT) or Universal Time Coordinates (UTC/Z)
* Storage
- Import Data:
import data from the specified (JSON) file (see Storage Data below)
- Delete All:
delete all storage data (destinations memory)
About Data Filtering
GliderSK uses Simple Moving Average (SMA) to average data and filter out sensor
- or piloting! - imprecisions, with a user-configurable Time Constant (see
Settings above) ranging from 0 (no filtering) to 60 seconds.
BEWARE! The more you increase the Time Constant, the longer the delay between
GliderSK readings and actual values!
GliderSK also allows to choose whether to display filtered (averaged) or instan-
taneous data in the various views, according to the user-specified Display Filter
(see Settings above):
- off: no data are filtered (all data are instantaneous)
- dt: time-derived data - speed, variometer and rate-of-turn - are filtered;
other data - acceleration, altitude and heading - are instantaneous
- all: all data are filtered
(acceleration is not considered time-derived since measured directly by the watch
sensor and not as the time derivative of speed)
However, the following exceptions apply:
- the Safety View always uses and displays filtered time-derived data;
current altitude and Heading Bug are always instantaneous
- the Varioplot View always displays instantaneous data
- Activity Recorded (FIT) data are always instantaneous
Importing Storage Data
GliderSK allows you to import data into the application storage space - iow.
destinations memory - from the web; to do so:
1. connect your device to Garmin Connect Mobile (GCM) via Bluetooth
2. [optional] use GCM to edit the Repository URL (GliderSK application) setting;
by default:
3. use the Import Data setting (see Setting above) to specify the JSON data file
name to download from the repository, without the .json suffix; example given
(for Switzerland airfields):
WARNING! Make sure your GCM phone/tablet doesn't go to sleep while performing
this step or it won't allow GCM to relay the data to your watch.
The destination slot(s) will then be updated (overwritten!) based on the data
contained in the file.
The format of a JSON destination data file is straight-forward; example given:
Provided you have some web service where to store them, you can write your own
data file(s). Just edit the Repository URL correspondingly (see point 2. above).
WARNING: If using HTTPS (SSL), make sure the website's certificate is from a
well-known Certification Authority (CA) or GCM will refuse to download the data.
Calibrating the Device Sensor
GliderSK allows you to calibrate/correct your device's barometric sensor using
the following formulas:
QFEcalibrated = QFEsensor * Crel + Cabs
If you suspect your device's sensor is inaccurate, you shall:
1. install the PilotAltimeter widget to access the device's *QFE* readings
(unfortunately, this falls out of GliderSK scope/purpose)
2. take down multiple QFE readings, at different altitude, using your device's
*raw* QFE and a reliable, calibrated, reference barometer
3. import those readings in a LibreOffice Calc (or Microsoft Excel) spreadsheet
and obtain the Crel and Cabs coefficients by performing a linear regression:
where Crel = Slope and Cabs = Intercept
(curve-fitting for dummies:
4. set Altimeter -> Correction -> Relative/Absolute values to the calculated
Not an easy feat. But if you must...
When using GPS devices, you should be aware that:
- GPS is very accurate for location (latitude/longitude) information;
even more so when coupled with GLONASS (at the cost of battery usage).
- (Garmin) UltraTrac feature is very cool to save battery but does NOT
refresh location information frequently enough for GliderSK purpose.
The ConnectIQ framework does NOT allow applications - like GliderSK - to
control the location source (GPS, GLONASS and/or UltraTrac). The only way
to circumvent that limitation is to
The ConnectIQ application launched afterwards will then retain those settings.