Altair | Glide Computer and Navigation System | Using XCSoar as a Problem Solving Tool

How a glide computer can help solve many of
your problems when flying cross-country
Michael Brandon, Southern Cross Gliding Club
12 September 2014
A quick overview of glide computers
A quick overview of XCSoar
Problems you might encounter and how
XCSoar can help you solve them
Questions and answers
◦ but feel free to ask questions along the way
The presentation focuses on cross-country
flying, but much of it is also relevant to flying
at Camden
As the name implies, it’s a computer…
…with some specialised gliding software
…and a GPS receiver so it knows where you are
…and (usually) maps and waypoints so it knows
what is below you
…and (sometimes) airspace information so it
knows what airspace restrictions are around you
The Cambridge 303 in the DG-303 is a glide
computer, although it doesn’t have maps or
airspace information
The new LXNAV LX 8080 in the DG-1000 is a
more modern glide computer
Clockwise from left: Oudie running SeeYou Mobile, Cambridge 303,
Altair running XCSoar, LX 8080 (shown to scale)
It’s the software component of the glide
You supply the computer and GPS receiver
You can download the software from the
XCSoar web site ( or install
the Android app from Google Play
You can download maps, waypoints and
airspace information from the Internet
XCSoar is open source software
◦ It’s free for anyone to use
◦ New versions and updates are released frequently
The simplest option is a modern Android smartphone
(eg HTC, LG, Samsung, Sony)
◦ XCSoar isn't available for the iPhone or iPad, or Windows Phone
Another option is a small Android tablet with built-in GPS
Using a car navigation GPS works, but only on some
brands (eg Navman) and you need to hack the device first
◦ XCSoar doesn’t work on Garmin or TomTom car GPSs
Another option is a Kobo eBook reader (eg Kobi Mini), but
this is experimental and you have to attach a GPS receiver
Using a PDA (eg iPAQ) was common in years past, but
PDAs are a superseded technology
You can run XCSoar on your PC at home to experiment
Some way to mount the device
securely in the cockpit
◦ Most smartphones have suction mounts
available from the manufacturer
◦ All car GPSs come with suction mounts
◦ Third party suction mounts (eg from
RAM Mount) may be expensive but can
work well
Some way to supply additional power
◦ The internal battery in your device is
probably fine for an hour’s flying around
Camden, but for a long cross-country
flight you need supplementary power
◦ Small USB battery packs are readily
available at a reasonable price
The standard XCSoar screen shows a moving
map and some “InfoBoxes”
◦ You need to install a map for your region
The InfoBoxes display useful information
◦ There are lots of InfoBoxes to choose from (100+)
◦ You choose which ones you want displayed
◦ You configure how many you want displayed and where
they appear on the screen
You configure how you want XCSoar to work
◦ There are lots of settings to configure (150+)
◦ Configure the settings before you fly, not in the air!
You access the settings by double-tapping on
the screen, then following the menus
You can “draw” on the screen to access some of
XCSoar’s features
◦ eg swiping up or down zooms the map in or out
The screen can be oriented in portrait or
landscape mode, but is shown here in portrait
mode for convenience
Where am I?
Which way is the wind blowing?
How do I centre this thermal?
How good are the flying conditions?
How fast should I fly?
How high should I fly?
Am I infringing airspace restrictions?
Which direction should I fly?
How well am I flying?
How far to the next turnpoint?
How do I ensure that I fly around the turnpoint?
How am I going on task?
How far am I from home?
How long have I been flying?
I’m running out of lift; how do I get back to a thermal?
Will I make it home?
I'm not going to make it home; where can I land?
I've outlanded; where am I?
XCSoar can’t teach you to use XCSoar
◦ Like it or not, you need to read the manual if you want to
use XCSoar successfully
◦ And yes, you need to read it more than once
◦ And no, you can’t read it in the air…
XCSoar can’t make you fly safely
◦ You’re the Pilot In Command, so you’re responsible for
the decisions you make and the actions you take
◦ XCSoar provides you with information, but you need to
use that information wisely
◦ Any glide computer can be a distraction if you let it;
remember that your primary responsibility is to fly the
aircraft (“aviate, navigate, communicate”)
◦ Computers can fail, so you still need a compass and
charts for cross-country flying, and you must know how
to use them
In the rest of the presentation, I assume you have
already loaded maps into XCSoar for the region
where you are flying
Rather than describe points in exhaustive detail, I
include references to the XCSoar 6.7 manual
(dated June 2014) which you can read for more
The configuration settings I describe and the
InfoBoxes I show are the ones I have found most
useful; you need to decide what is best for you
I’ll make this presentation available if you would
like to refer to it later
XCSoar displays a moving map (see section 4.1 of the manual
dated June 2014)
You can zoom the map in and out (4.3)
You can move the map around (4.4)
Swipe left or right on the screen
You can orient the map in different ways: “north up” (north at
the top), “track up” (the direction you are travelling), “heading
up” (the direction you are pointed) or “target up” (the direction
you want to go) (4.2, 6.12)
I prefer “north up” so I can align the map with my charts and
estimate compass bearings easily (4.2)
Display/Pan On, then move the map with your finger
You can see more of the map by hiding the InfoBoxes
temporarily (3.6, 3.12)
Swipe up or down on the screen (3.12) or
Display/Zoom In and Display/Zoom Out (4.3)
Config/Config/System/Map Display/Orientation/Cruise
orientation=North up (13.5)
If you want to align the map with the ground below, you can
select “track up” or “heading up”, but the map tends to dance
around, so “target up” is a better option (4.2)
Config/Config/System/Map Display/Orientation/Cruise
orientation=Target up (13.5)
XCSoar can automatically calculate the wind
speed and direction from your drift whilst
thermalling (7.5)
◦ Config/Config/System/Glide
Computer/Wind/Auto wind=Circling (13.12)
XCSoar displays a grey arrow on the map
showing the wind speed and direction (7.4)
When a significant change in wind speed or
direction is detected, XCSoar displays an
alert (6.15)
The “Wind speed” InfoBox shows the speed
and direction of the wind (12.5)
The “Wind arrow” InfoBox shows the wind
direction graphically, but the arrow is
oriented “heading up”, which may be
confusing if you have the map oriented
“north up” (12.5)
The wind varies with altitude in both
speed and direction; XCSoar collects
this information during flight and can
display it graphically (7.11)
◦ Info/Analysis/Wind At Altitude
Warning: wind speed and direction
change over time; since you are likely
to spend most of the flight up high,
the wind information recorded for low
altitude may no longer be current!
Warning: when landing or outlanding,
always confirm the wind direction at
ground level using indicators other
than XCSoar!
XCSoar can zoom in when circling, making it easier to see the
“snail trail” and its indications of lift strength (4.3)
XCSoar records your climb rate whilst thermalling and can
display this in a “thermal assistant” at the bottom left of the
screen, which you can use to centre the thermal (7.9)
Config/Config/System/Map Display/Orientation/Circling zoom=On
Config/Config/System/Gauges/FLARM, Other/Thermal assistant=On
I’ve generally not found the thermal assistant very helpful;
when thermalling, I’m focused on flying the aircraft and don’t
have time to look at XCSoar
I’ve not found the thermal assistant any better than the
techniques we’ve all been taught for centring thermals
The only time I’ve found it useful is if I’ve lost contact with the
thermal, and the indicator points me to where I can reconnect
The “Circle Diameter” InfoBox shows your circle size in metres
and circle time in seconds, which you may find helpful
Warning: don’t let XCSoar be a distraction when you should be
looking outside the aircraft!
XCSoar has a number of InfoBoxes which
indicate how good the flying conditions are
“Last thermal average” and “Thermal
average” show the average climb rate in the
last thermal and in the current thermal, in
knots (12.4)
“Last thermal gain” and “Thermal gain”
show the height gained in the last thermal
and in the current thermal, in feet (12.4)
“Last thermal time” shows the amount of
time spent climbing in the last thermal
“Thermal average over all” shows the
average climb rate for all thermals, in knots
XCSoar can display a bar chart
showing the average climb
rate for the last 20 thermals,
in knots (5.15)
◦ Info/Analysis/Climb
The current MacCready setting
is shown by the red line
The trend is indicated by the
blue line
XCSoar can calculate the optimal speed to fly based on
the aircraft’s performance characteristics and the
expected lift strength, using MacCready Theory (6.6)
You can set the expected lift strength (the “MacCready
setting”) manually (6.2)
Config/Config/System/Glide Computer/Glide
Computer/Auto MC mode=Both (13.11)
Config/MacCready Auto (6.13)
XCSoar can cater for the fact that whilst you can afford
to fly faster at high altitude, you need to be more
conservative as you get closer to the ground (6.7)
Config/MacCready+ or Config/MacCready–
You can allow XCSoar to calculate the recommended
MacCready setting automatically (6.13)
You need to configure the aircraft type and performance, as
described later
Config/Config/System/Glide Computer/Safety Factors/STF
risk factor=0.3 (13.10)
The “Speed MacCready” InfoBox shows the optimal
speed to fly at the current MacCready setting (12.6)
The “MacCready Setting” InfoBox shows the current
mode (manual or automatic) and current value (12.6)
A canny pilot once advised me to “Get high, stay
high”, and whilst that provides a good chance of
making it home, it can result in a long, slow
XCSoar records your average climb rate at
different heights and can display this in a
“thermal profile” indicator at the top left of the
screen, which you can use to judge the optimal
height band to fly in (7.7)
◦ Config/Config/System/Gauges/FLARM, Other/Thermal
band=On (13.14)
The Y axis indicates height, the X axis indicates
climb rate and the black arrow indicates your
current height within the band
Warning: lift strength changes over time; since
you are likely to spend most of the flight up
high, the lift strength information recorded for
low altitude may no longer be current!
XCSoar can display airspace boundaries on
the map (8.1)
◦ Config/Config/System/Map
Display/Airspace/Airspace display=Auto (13.9)
If airspace information isn’t embedded
within your map database, you need to
supply an airspace file and configure
XCSoar to use it (14.4)
◦ Config/Config/System/Site Files/Site
Files/Airspaces (13.4)
XCSoar can display colour-coded alerts as
you approach an airspace boundary and if
you infringe the airspace (8.2)
◦ Config/Config/System/Map
Display/Airspace/Warnings=On (13.9)
◦ Config/Config/System/Map
Display/Airspace/Margin=500 ft (13.9)
XCSoar can display a diagram
showing the airspace from
ground level upwards (8.4)
◦ Info/Analysis/Airspace
The diagram displays the
airspace from where you are
(left) to 50 km ahead in the
direction you are tracking (right)
Your current height is indicated
by the black arrow on the left
XCSoar displays a dark blue arrow
on the map indicating the direction
to fly to the next turnpoint (6.12)
If there is no wind, the optimal
direction is towards the next
turnpoint, but if there is a
crosswind, you need to head
slightly upwind; XCSoar takes this
into account (6.12)
The “Next waypoint” InfoBox shows
the name of the next turnpoint and
the direction to steer towards it,
with chevrons pointing left or right
XCSoar has separate map
orientations for “cruise” and
“circling” modes (4.2)
When thermalling, I orient the
map “target up” so I can easily
see which direction to exit the
thermal (4.2)
◦ Config/Config/System/Map
orientation=Target up (13.5)
XCSoar has a number of InfoBoxes which
indicate how well you are flying
“Speed ground” shows your ground speed, in
km/h (12.2)
“Percentage climb” shows the proportion of time
spent thermalling (12.6)
“Task cruise efficiency” shows your cruise
efficiency compared with optimal MacCready
performance, although what this actually means
is not explained (12.6)
“Speed task achieved” shows your task speed, in
km/h (12.8)
“Task progress” displays a clock-face indicator
of progress through the task (12.8)
“Speed task last hour” shows your average
cross-country speed over the past hour, in km/h
XCSoar has a number of InfoBoxes
which indicate the distance and
time to the next turnpoint
“Next distance” shows the distance
to the next turnpoint, in km, as well
as the name and direction (12.7)
“Next time to go” shows the time
remaining to reach the next
turnpoint, assuming (probably
unrealistically) that the ideal
MacCready speed is achieved (12.9)
“Next time to go (ground speed)”
shows the time remaining to reach
the next turnpoint, assuming the
current ground speed (12.9)
XCSoar can zoom in on the
map when approaching a
turnpoint so you don’t miss it
◦ Display/Zoom Auto
You don’t want to have your
badge claim rejected by the
Badge Lady!
XCSoar can display a diagram
showing your progress on
task (5.15)
◦ Info/Analysis/Task
XSCoar can display a summary
of time, distance and speed
information for the task (4.12)
◦ Info/Info/Status/Task
XCSoar has a number of
InfoBoxes which display distance
from home information
“Final distance” shows the
distance around the remaining
turnpoints, in km (12.7)
“Distance home” shows the
distance to the home waypoint,
if one is defined, in km (12.7)
“Distance takeoff” shows the
distance and direction to the
take-off point (undocumented)
XCSoar has a number of InfoBoxes which display
time information
“Time local” shows the current time of day (12.9)
“Flight duration” shows the elapsed time since
take-off (12.9)
“Task time to go (ground speed)” shows the
estimated time remaining to complete the task
at the current ground speed (12.9)
“Task arrival time” shows the estimated time of
day you will complete the task, assuming the
ideal MacCready speed is achieved (12.9)
Unfortunately there isn’t any “Task arrival time
(ground speed)” InfoBox
XCSoar displays the time of day in “hh:mm ss”
format, and elapsed time in “mm’ss” format if
less than an hour, or “hh:mm ss” otherwise
XCSoar can display a summary
of time information on the one
screen (undocumented)
◦ Info/Info/Status/Times
XCSoar understands how the
date and location affect the
time of local sunset, and will
display a warning if the
estimated task completion
time is after sunset (5.16)
XCSoar displays markers for the last 20
thermals you circled in (4.10, 7.8)
◦ Note: section 4.10 of the manual says
markers for all thermals are displayed,
which is incorrect
The location of the marker on the map
is adjusted to account for wind drift
with height (7.8)
If you tap on a thermal marker, XCSoar
displays information about the average
lift strength and how long ago you
were there (4.10, 5.3)
Warning: none of the above guarantees
the thermal will still be there!
XCSoar can display a “snail trail” which
is colour-coded to indicate rising air
◦ Config/Config/System/Map
Display/Elements/Trail length=Short (13.6)
◦ Config/Config/System/Map
Display/Elements/Trail type=Vario #1
The width of the trail can indicate the
strength of the lift (4.8)
• Config/Config/System/Map
Display/Elements/Trail scaled=On (13.6)
The location of the trail can be
adjusted for wind drift (4.8)
◦ Config/Config/System/Map
Display/Elements/Trail drift=On (13.6)
XCSoar can display a colour-coded above/below final glide
indicator on the left of the screen, with the height margin or
the amount of height still required (6.10)
Green indicates above final glide, so if you have a comfortable
margin you should make it home; red indicates below final
glide, so you have more thermalling to do
If you are below final glide but there are landable waypoints
within glide range, the bar is orange
The bar is usually split vertically; the left half indicates
above/below final glide at the current MacCready setting, and
the right half using a MacCready setting of zero ie assuming no
more lift (6.10)
Config/Config/System/Gauges/FLARM, Other/Final glide bar=On
Config/Config/System/Gauges/FLARM, Other/Final glide bar MC0=On
This works at Camden as well!; if you haven’t declared a task,
XCSoar treats the take-off point as your intended destination
If you are below final glide you will drift with the wind whilst
thermalling; XCSoar can take this into account (6.10)
Config/Config/System/Glide Computer/Glide Computer/Predict wind
drift=On (13.11)
So that XCSoar knows the performance of your aircraft, you need to configure the
type of aircraft you are flying before each flight (6.3)
You need to configure the minimum safety height you want to arrive at a landing
place so you can do a proper circuit (6.8)
Config/Config/System/Glide Computer/Safety Factors/Polar degradation=5% (13.10)
Note: this should really be set on a “per glider” basis rather than globally, but I haven’t
managed to convince the developers to provide this feature; however, XCSoar is open
source, so I can add the feature myself if I really want it!
Glider performance degrades during flight due to insects sticking to the wings, so
you can configure XCSoar to reduce the expected performance by 1% per hour of
flight time (undocumented)
Config/Config/System/Glide Computer/Safety Factors/Arrival height=1000ft (13.10)
No aircraft performs as well as when fresh from the factory, so you need to
configure a “fudge factor” to reflect the slightly reduced performance (6.3)
Config/Config/Plane (13.28)
Config/Config/System/Glide Computer/Safety Factors/Auto bugs=On
You need to configure whether XCSoar should do glide range calculations using
the current MacCready setting or a “safety” setting (it’s safest to assume no more
lift) (4.11)
Config/Config/System/Glide Computer/Route/Reach polar=Safety MC (13.13)
Config/Config/System/Glide Computer/Safety Factors/Safety MC=0.0 kt (13.10)
XCSoar can display landable waypoints on the
map, colour-coded to indicate whether they are
within glide range (4.5)
◦ Config/Config/System/Map
Display/Waypoints/Landable symbols=Traffic lights
XCSoar can display next to landable waypoints
within glide range the height margin you have
above your safety height (4.5)
◦ Config/Config/System/Map Display/Waypoints/Arrival
height=Terrain avoidance glide (13.7)
XCSoar can display a shaded region on the map
showing the area within glide range above your
safety height (4.11)
◦ Config/Config/Glide Computer/Route/Reach
display=Shade (13.13)
XCSoar has InfoBoxes showing the name of and
direction to the two best alternate landable
waypoints (12.12)
◦ The direction is colour-coded blue if the alternate is
within glide range (undocumented)
XCSoar can display a list of six
landable waypoints using
colour-coding to indicate
whether they are within glide
range above your safety height
◦ Nav/Alternates
You can sort the list by height
margin, closest on track or
closest heading home (5.10)
◦ Config/Config/System/Glide
Computer/Safety Factors/Alternates
mode (13.10)
Just because XCSoar thinks an airfield is
landable doesn't mean it is (perhaps the
airfield is closed)
Just because XCSoar thinks an airfield is
within glide range doesn't mean it is (perhaps
there's a wind change coming)
You should err on the side of caution; the
large flat paddock below may be a safer
option than the airfield on the edge of your
reported glide range
XCSoar can display the current
GPS coordinates, and the
direction and distance to the
nearest waypoint (4.12)
◦ Info/Info/Status/Flight
I’ve lots of answers, some of them right...
You’ve been a wonderful audience
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