GPS Navigation
Using the Apollo GX-55
May 2008
Motivation

GPS is a powerful tool for search and rescue
–
–
Allows very precise search patterns
Makes manageable what would otherwise be very difficult
patterns




–

Expanding square at any angle
Creeping line along a course
Offset route searches
Grid searches over indistinct terrain
GPS should be our primary tool for Search and Rescue
navigation
GPS is of course also very handy for general
navigation
Before we begin…
How does one learn to use GPS?


This presentation provides a good foundation of
knowledge, but it will be forgotten quickly if not used
Hands-on practice is the only way to become proficient
–
Start out with the software simulator, if possible


–
–
The simulator has limitations and a few bugs, but it is worthwhile
Information on how to acquire the simulator can be found at the
end of this presentation
Download the “shorthand guide” from the wing website and
keep it with your mission kit
Practice with the real device in flight
Before we begin…


After you’ve had some practice, consider
reviewing the GPS user manual (or study this
presentation again)
When you think you have it down, try teaching
someone else!
GPS Navigation Using the GX-55
Course Outline
This presentation is organized in six parts
 Fundamentals of GPS Navigation
 Introduction to using the Apollo GX-55
 Basic tasks with the GX-55
 GX-55 search patterns
 Safety issues
 Using the GX-55 simulator software
Part 1
– Fundamentals of GPS Navigation



How it works: The basics
Accuracy
Describing locations
How it Works – The Basics


Spaced-based system
(unlike Loran or VOR)
‘Constellation’ of 24 satellites in
six orbital planes
–
–
–
21 active satellites
plus 3 operating spares
In “High” orbit of about
12,000 miles
Each circles the Earth about
every 12 hours
How it Works – The Basics

GPS satellites transmit information
–
–
“Pseudo-random” code with time information
Satellite orbital position data


–

“Almanac” data
“Ephemeris” data
Updated atmospheric models
GPS receiver uses this data to figure out what
time it is and what time the signals were sent
How it Works – The Basics



GPS receiver measures distance to satellites by
determining the amount of time that the radio signal
takes to travel from each satellite
Each distance measurement effectively defines a
sphere around a satellite
Multiple satellites must be used to determine a position
–
–
–
Given two satellites, two sphere intersect to determine a circle
Given three satellites, a sphere and a circle intersect to
determine two points
A fourth satellite can determine a positive 3D position
Accuracy

A complex question
–

DOD has a 66 page document describing the
performance of GPS Standard Positioning
Service (SPS)
The short story
–
–
Garmin states that their GPS receivers “are
accurate to within 15 meters on average”
Typically about 6 to 12 Meters accuracy can
be seen
Accuracy

Accuracy and reliability is actually a complex subject.
There are many factors that can impact system.
–
–
–
–
Receiver errors
Atmospheric (ionosphere) errors
Solar activity (sun spots and solar storms)
Location of receiver
(some parts of the Globe get better coverage than others)
–
–
–
–
–
–
Orbital errors (inaccuracies in the reported orbital position)
Poor satellite geometry (satellites lined up or bunched up)
Limited number of satellites in view
Satellite malfunctions (or satellites taken out of service)
“Multi-path” errors (radio signal reflections)
Results vary hour by hour, day by day
Accuracy


There is a substantial difference between typical
accuracy and worst-case accuracy
Described as a statistic: x% had an error of y meters or
less
Typical 95% horizontal error results for a typical day:
Global average
7.8 – 8.3 meters
Average for worst site
(on globe)
19.2-19.7 meters
Errors worse than 30 meters are possible given the potential
for various atmospheric conditions and receiver faults and
the possibility that satellites can be taken out of service
Accuracy and
“Selective Availability”



Past feature of GPS SPS that purposefully degraded
accuracy of position determination for non US-military
use
Civilian accuracy was typically about 100 meters under
Selective Availability
SA was discontinued May 1, 2000
–
–
Has not been used since
It's been replaced by “selective deniability,” which allows the
US military to geographically designate areas in which to
degrade GPS quality.
Comparing Accuracy
with and without SA – A sample
The plots show that SA causes 95% of the points to fall within a radius of
60.7 yards. Without SA, 95% of the points fall within a radius of 7.9 yards.
Comparing Accuracy
with and without SA – Recap


Before, with 100 meter
typical accuracy allowed
you to identify what
stadium you were in
Now with 6-12 meter
typical accuracy, you can
tell about which yard line
you are on
Accuracy – WAAS

Wide-Area Augmentation System
–
–
–
Designed specifically for aviation
Commissioned by FAA in 2003
Uses ground stations and satellites

–
–
Augments GPS Standard Positioning Service
Provides better integrity and accuracy

–
–
25 ground stations cover the entire US and parts of Canada and
Mexico
Typical accuracy of 3-5 meters horizontal, 3-7 meters vertical
Can be used for precision approaches
WAAS is not a feature of the Apollo GX-55 used by CAP
Describing Locations
A Choice to Understand


We describe latitude and longitude normally using
degrees and minutes
When dealing with fractions of minutes there is,
however, a choice
–
There are essentially two options:
1.
2.
–
One can use seconds
(of which there are 60 in one minute)
One can use decimal-minutes
(i.e. tenths and hundredths of a minute)
Many GPS units can be configured to display one way or the
other
Describing Locations
CAP Standard Method

The standard we will use in CAP is
degrees and decimal minutes
–
Example:
45 degrees 35.4 minutes North
93 degrees 42.2 minutes West
–
–

This is the standard way the Air Force provides coordinates to
us for search and rescue
This is also the way our GX-55 normally displays position
information
In CAP we will not usually use “seconds” unless
working with another agency that wishes to do so.
Describing Locations
Communicating with Others

The seconds vs. decimal minutes question is a big source of
confusion even within our own ranks
–
–
–
–

Some people erroneously say “seconds” when they mean
“hundredths of a minute”
Some people say “point” or “decimal” when they should have said
“minutes” and “seconds”
Take nothing for granted when getting information
Be accurate and clear when giving information
Especially when working with other-agencies, triple-check all
coordinates to make sure we’re all speaking the same language
–
The Coast Guard Auxiliary normally uses Degrees-Minutes-Seconds
as their standard way of describing positions, but they will use the
word “decimal” or “point” to separate the three parts of the coordinate
Describing Locations
Yet Another Approach to be Aware of

Some GPS units (including the GX-55) also
offer the option to display position information
using Universal Transverse Mercator” (UTM)
–
–
–
An alternative to using degrees and minutes
Beyond the scope of this course
We will not use this
Part 2 –
Introduction to using the Apollo GX-55




Equipment overview
The controls and function/page hierarchy
Review terminology
Tour of display pages – how to read displayed
information
Our Equipment: Apollo GX-55



Extensive
Database
Scrolling Map
Display
Search and Rescue Functions
Power
Switch
GX-55 Controls
“Smart” Keys
& “annunciators”
“Hard” keys
“Small”
Knob
“Large”
Knob
Large & Small Knobs

Moving between pages
–
–
Large knob selects most main pages
Small knob selects sub pages



Different scale maps
Sub-pages in set-up areas
Entering Data
–
–
Large Knob moves cursor
Small Knob changes word or character at cursor
Hard Keys





NAV
MAP
NRST
INFO
SEL
Navigation display pages, flight plan setup, etc.
Map display pages
Pages with nearest waypoints
Database information pages
Select



Enter
Complete some data entry action


D
Make a cursor appear so you can change a value on a page
When a question is being asked, make the cursor
disappear, effectively responding “no” to the question
Also used to answer “yes” in response to a question
“Direct-To” (short-cut flight-plan from current location)
Function/Page Hierarchy:
Getting to the screen page you want
Main hierarchy:
 Hard key
(example: MAP)
 Large Knob
(example: Map Setup)
 Small Knob
(example: Route Line, Map Orient, & Map Reference)
Function/Page Hierarchy:
Getting to the screen page you want
Other paths:
 Hard key
(example: NAV)
 Smart key
(example: FPL – Flight Plan)
 Large knob
(example: Create new flight plan)
Smart Keys
Three major uses
–
Page navigation


–
–
FPL – Flight plan
DB – Database
Short-cut to change values on page (without
pressing SEL and turning knobs)
Clutter/de-clutter features on maps

Three-way toggles for waypoints: show waypoint icon,
show icon and label, and hide
Terminology: Waypoint


A specific named location either defined by the
user or defined in the instrument’s database
Database waypoints come in flavors:
–
–
–
–
Airport
VOR
NDB
Intersection (INT)
Terminology:
Defining Different Directions





Desired Track / Course
Bearing
Track
Heading
Track Angle Error
Note: All directions in GPS unit are magnetic
Desired Track
North (magnetic)
TO Waypoint
DTK
FROM Waypoint
 DTK – Desired Track: course direction, direction between
two waypoints
Bearing
North (magnetic)
TO Waypoint
BRG
FROM Waypoint
 BRG – Bearing: direction to a waypoint
Heading
North (magnetic)
TO Waypoint
FROM Waypoint
Heading
 Heading – direction the aircraft is pointed
Track
North (magnetic)
TO Waypoint
TRK
FROM Waypoint
 TRK – Track: direction the aircraft is going
Track Angle Error
North (magnetic)
TO Waypoint
DTK
DTK
TRK
TAE
FROM Waypoint
 TAE – Track Angle Error: difference between track and
desired track
Recap –
Defining Different Directions
North (magnetic)
TO Waypoint
BRG
DTK
TRK
TAE
FROM Waypoint
Heading
 DTK – Desired Track: course direction, direction between
two waypoints
 BRG – Bearing: direction to a waypoint
 TRK – Track: direction the aircraft is going
 Heading – direction the aircraft is pointed
 TAE – Track Angle Error: difference between track and
desired track
A Tour of Display Pages
How to Read Displayed Information




NAV ETE
Split Screen Map
Full Screen Map
More Pages
Reading the NAV ETE Display
“Estimated Time
Enroute” Label
TO-Waypoint Identifier
(Airport DLH, Duluth)
Distance
off-track
(0.17 NM left
of course)
Bearing to the
TO-waypoint
(017 degrees)
Distance to the
TO-waypoint
(43.5 nautical miles)
Estimated Time Remaining
Value (26 minutes)
Graphic Course Deviation
Indicator (CDI)
 Triangle at center is
TO/FROM indicator
(pointing up indicates “To”)
 CDI “needle” is at the end
of bar graph line (indicates
we need to go right to get
back on course)
Reading the NAV ETE Display
Diamond indicates
additional pages of
information can be selected
by turning the small knob
Relative Bearing Indicator
arrow points to approximate
bearing relative to current track
– It points in one of 8 directions
Some ‘Diamond’ NAV ETE Pages
(Use small knob to move between)
Reading the NAV ETE Display
Estimated return time to the
“TO-waypoint” (13 minutes)
Increasing if moving away;
estimated based on current
ground speed
Differences when past
“TO waypoint”
Graphic CDI
center triangle
points down to
indicate
“FROM”
– i.e. past the
“TO-waypoint”
FROM-side of
destination
waypoint
FROM
Waypoint
TO-side of
destination
waypoint
TO
Waypoint
ETE Display
Course Deviation Indicator
CDI Sensitivity 0.3 nm
Full deflection, 0.3 nm
 Each dot, 0.01 nm
 Each tick, 0.04 nm

CDI Sensitivity 1.0 nm
Full deflection, 1.0 nm
 Each dot, 0.05 nm
 Each tick, 0.14 nm

CDI Sensitivity 5.0 nm
Full deflection, 5.0 nm
 Each dot, 0.24 nm
 Each tick, 0.71 nm

Reading the Split Screen Map Page
To-Waypoint Identifier
(Airport DLH, Duluth)
Ground speed
(100 Knots)
Map scale
(15 NM measured from top to bottom)
Current track direction
(014 degrees)
Reading the Split Screen Map Page
Remaining distance to
the TO waypoint
(114 Nautical Miles)
Bearing to the TO
Waypoint from current
position (014 degrees)
Course-deviation indicator
(exactly on-course or slightly left of course)
Reading the Split Screen Map Page
Route-line
(note map-orientation
is currently North-up)
Aircraft current
position on map
Reading the Full Screen Map Page
TO Waypoint Identifier
(Airport DLH, Duluth)
Map scale
(30 NM measured from top to bottom)
Bearing to the TO Waypoint from
current position (017 degrees)
Remaining distance to
the TO waypoint
(75.0 Nautical Miles)
Reading the Full Screen Map Page
Route-line
(note map-orientation
is currently North-up)
Waypoint
Location
Waypoint Identifier
Aircraft current
position on map
Map Clutter/De-clutter Smart Keys


Smart keys on maps
are used primarily for
clutter/de-clutter control
For each kind of
waypoint, there is a
three-way toggle
–
–
–

FBL (Faribault) Airport
icon shown and labeled
Display icon with label
Display icon without
label
Don’t display
Annunciators above
keys indicate current
state of each option
APT (airport) annunciator fully lit, so
airports will be shown and labeled
Map Clutter/De-clutter Smart Keys


Smart keys on maps
are used primarily for
clutter/de-clutter control
For each kind of
waypoint, there is a
three-way toggle
–
–
–

Halfway VOR
(icon only)
Display icon with label
Display icon without
label
Don’t display
Annunciators above
keys indicate current
state of each option
VOR annunciator half-lit, so VORs
will be depicted as unlabeled
icons.
Map Clutter/De-clutter Smart Keys


Smart keys on maps
are used primarily for
clutter/de-clutter control
For each kind of
waypoint, there is a
three-way toggle
–
–
–

Display icon with label
Display icon without
label
Don’t display
Annunciators above
keys indicate current
state of each option
INT annunciator unlit, so
intersections will not be depicted
Numbered Smart Keys


An annunciator which
is a number indicates
that there are more
smart keys that can
be used for the
current screen
Press the numbered
smart key to get
another set of smart
keys
“1” indicates that this is the first
set of smart keys for this screen
More Pages
Lets now look at the pages that we can get to
after pressing each of the four page-selection
hard keys
–
–
–
–
NAV Pages
MAP Pages
NRST Pages
INFO Pages
NAV Key Pages
Select with Large Knob After Pressing NAV

ETA & BRG
–



RAIM Prediction
Altitude Assist
Parallel Track
–

Also shows distance
Useful for offset route
search
GPS Position
–
Basic Lat. & Long.






Countdown Timer
Arc Assist
To/Next Wpt (Distance)
To/Next Wpt (ETE)
To/Next Wpt (ETA)
From/To/Next Waypoint
MAP Key Pages
Select with Large Knob After Pressing MAP




Split Screen Map – Map Plus Nav Info
Full Screen Map
Search and Rescue Map
[if configured under Map Setup]
Map Setup
–
Several sub-screens can be selected using the
small knob
NRST Key Pages
Select with Large Knob After Pressing NRST








Airport (ARPT)
VOR
NDB
INT
User WPT
Search Around WPT
Runway Limits
SUA (special use airspace)
For each kind of waypoint, select
which of the 20 nearest
instances using the small knob
INFO Key Pages
Select with Large Knob After Pressing INFO









Identifier, Type, and
Name
Radial and distance
Bearing and distance
Map
Frequencies
Approaches
Lat/Long
Sunrise/Sunset
WPT comment
Review…

What information can you get from this page?
Review – Here are a Couple Other
Views (taken shortly afterwards)
Part 3 –
Basic tasks with the GX-55










Select a waypoint and go direct to it
View current Lat & Long
Go directly to the nearest airport
Enter a user waypoint
Set up SAR functions
View a SAR Map
Remember a Current Position
Creating & Activating a Flight Plan
Useful Tricks
Common Problems
Select a waypoint and go direct to it






Press the
Direct-To Key ( D )
Type of waypoint is flashing (i.e. has cursor);
use small knob to select type of waypoint
Use large knob to move cursor to first character of
waypoint identifier
Use small knob to change character
Repeat using large knob to move cursor and small
knob to change character and form the name of the
destination waypoint.
Press Enter Key
Select a waypoint and go direct to it






Press the
Direct-To Key ( D )
Type of waypoint is flashing (i.e. has cursor);
use small knob to select type of waypoint
Use large knob to move cursor to first character of
waypoint identifier
Use small knob to change character
Repeat using large knob to move cursor and small
knob to change character and form the name of the
destination waypoint.
Press Enter Key
Select a waypoint and go direct to it






Press the
Direct-To Key ( D )
Type of waypoint is flashing (i.e. has cursor);
use small knob to select type of waypoint
Use large knob to move cursor to first character of
waypoint identifier
Use small knob to change character
Repeat using large knob to move cursor and small
knob to change character and form the name of the
destination waypoint.
Press Enter Key
Select a waypoint and go direct to it






Press the
Direct-To Key ( D )
Type of waypoint is flashing (i.e. has cursor);
use small knob to select type of waypoint
Use large knob to move cursor to first character of
waypoint identifier
Use small knob to change character
Repeat using large knob to move cursor and small
knob to change character and form the name of the
destination waypoint.
Press ENTER Key
View Current Lat & Long


Press NAV key
Turn large knob until ‘GPS Position’ screen appears
Go Directly to the Nearest Airport

Press the NRST key
–

Press the Direct-to
Key ( D )
–
–

A page will display
the closest airport
The waypoint
selection
screen will appear
with a
flashing cursor
Leave all information
unchanged
Press ENTER
Enter a user waypoint
(by Lat & Long)






Press NAV Key
Press DB Smart Key
Turn large knob until
‘Create User Wpt by
Lat/Lon’ screen appears
Press ENTER
Use large & small knobs
to enter a name for the
new waypoint; also use
knobs to enter lat & long
Press ENTER to finish
Set up SAR Functions
Part 1: Turn Map On




Press MAP
Turn large knob until
setup (Route Line)
screen appears
Turn small knob until
SAR MAP ON/OFF
screen appears
If SAR MAP is off, press
the SAR Smart key to
turn it on
Set up SAR Functions
Part 2: Select Sectional Chart
(SAR MAP ON/OFF Screen)
Method 1• Press SEL (cursor will appear as flashing item)
• turn Large Knob until Position setting flashes
• turn the Small Knob until the desired sectional map name
(MSP, for example) appears
• Press ENTER
Method 2• Press POS smart key until MSP appears
View a SAR Map


Press MAP
Turn large knob until SAR Map appears
–



You will see Smart keys labeled GRD, MRK, and PAT
Press GRD smart key and zoom scale using small knob to see
grid lines
Press GRD smart key to see grid number
Press GRD2 smart key to see quarter grids
Remember a Current Position
(from SAR Map Page)



Press MRK
Smart key
Use knobs to
select name
Press ENTER
Creating a New Flight Plan
Part 1: Create and Name the Plan





Press FPL
(if not available,
press NAV first)
Turn Large knob until
‘Create New Flight
Plan’ Page appears
Press SEL
Use Large & Small
knobs to enter the
flight plan name
Press ENTER when
the name is complete
Creating a New Flight Plan
Part 2: Begin Editing First Leg


Turn the Small knob to
start inserting waypoints
Press SEL
Creating a New Flight Plan
Part 3: Enter Origin


At the INS? Prompt, press
ENTER
Use Large & Small Knobs
to select waypoint and
press ENTER
Creating a New Flight Plan
Part 4: Enter Leg Destination


At the INS? Prompt, press
ENTER
Use Large & Small Knobs
to select waypoint and
press ENTER
Creating a New Flight Plan
Part 5: Edit Another Leg or End Flight Plan

At the INS? Prompt,
either…
– press ENTER to begin
editing another leg
or
– Press SEL to end the
Flight Plan
Activating a Flight Plan




Press FPL
(if not available,
press NAV first)
Turn the Large Knob until
your flight plan appears
(look for it by name)
Press SEL
Press ENTER
Other Flight Plan Actions




Press FPL
(if not available,
press NAV first)
Turn the Large Knob until
your flight plan appears
(look for it by name)
Press SEL
Turn the Small knob to see
other actions possible
(examples: Reverse,
Delete)
Useful Tricks

Pressing a hard key one time, when viewing a page
under another key, returns you to the last page viewed
under the key pressed
–

Useful for when you want to flip back-and-forth between a
MAP page and a NAV page
Pressing a hard key twice sends you to the default
page for that key
–
–
Pressing NAV two times will send you to the ETE NAV page
Pressing MAP two times will send you to the split-screen map
page
Common Problems

“Autonav” mode displays a series of NAV
pages, rotated in sequence – this can be very
annoying if entered inadvertently
–
–

Turn on by pressing ENTER while viewing a NAV
page
Turn off by pressing any key or turning any knob
Remember to set up correct sectional chart
when using SAR map
Review – What Page is This
It is the SAR Map Page
Review…
How does one get from the NAV ETE page to
the split-screen map page?
Two Ways:

Press MAP and turn the large knob until the
split-screen map page appears
Or
– Press MAP twice
–
Review…

What information can you get from this page?
Part 4 –
GX-55 Search patterns

Describing the patterns
–
–
–
–


Parallel Line (Grid)
Creeping Line
Expanding Square
Route and offset route
Programming patterns into the GPS
Flying to the pattern entry
Parallel Line Search Pattern
a.k.a. “Grid Search”


“US Grids” are areas
15 minute to a side,
serially numbered for
each sectional chart
(MSP means “Twin
Cities” sectional)
7.5 minute quarter
grids are named A, B,
C, and D – in
reading order, left to
right, top to bottom
46o 00’ N
B
A
414
D
C
45o 45’
MSP
413 A
445
446
45o 30’ N
93o 45’
94o 00’ W
93o 30’ W
Parallel Line Search Pattern
a.k.a. “Grid Search”

The GPS unit
labels the four
corners (and also
four search pattern
entry points) 1, 2,
3, and 4 –
clockwise starting
in northwest.
1
2
46o 00’ N
MSP
413 A
4
94o 00’ W
3
45o 52.5’ N
93o 52.5’ W
Describing a Parallel Line Pattern



Grid identifier and starting waypoint
(i.e. corner of quarter-grid)
Track spacing
Direction of tracks – either E/W or N/S
Note: Search area for a parallel line pattern in the GX55
is always a quarter-grid
Parallel Line Pattern Example
 Quarter Grid MSP 413A1
• Northwest corner of grid
MSP 413A
 Track spacing 1 NM
 Tracks running east to
west
MSP
413 A
Track spacing
Creeping Line Search Pattern


Shaped much like a parallel
line pattern, but with legs
aligned perpendicular to a
route (rather than by ordinal
directions)
Descriptive parts:
–
–
–
–
–
–
Starting point (any waypoint)
Direction
Starting left or right side
Track spacing
Leg length
Number of legs
Direction
Track
spacing
Starting
Waypoint
Starting on
left side
Expanding Square

Descriptive parts
–
–
–
–
Starting waypoint (at
center of pattern)
Initial direction
Track spacing
Number of legs
3s
s
s
2s
s
3s
2s
Initial
Direction
Offset Track Line Search
a.k.a. Route Search


For a returning
route search, 2
passes are made,
each ½ track
spacing offset from
base course
A non-returning
route search will
have a leg on the
base course
TO Waypoint
FROM
Waypoint
Offset Track Line Search
a.k.a. Route Search


For the purpose of using the GPS, we
will describe only one leg at a time
A route leg will either be…
–
–
On the course line (in which case a simple
flight plan will suffice)
Offset from the course line

Described as a distance offset and a direction
offset (either right or left of course)
Programming Patterns into GPS


Track-line/route searches accomplished using
Flight plans and the “Parallel Track” setup page
under NAV.
Programming for parallel line, creeping line,
and expanding square searches is begun by
pressing the PAT smart key while viewing the
SAR map page.
Programming the Parallel Line
(i.e. Grid) Search Pattern
Prerequisite:
MAP
The correct grid type (US Grid) and Sectional must be
configured in the under map setup.
Press MAP to view map pages
Turn large knob to view SAR map
page
PAT
Press the PAT smart key
If needed, turn the small knob to view
the “Parallel Line Search Page”
ENTER
Press ENTER to begin
Programming the Parallel Line
(i.e. Grid) Search Pattern
SEL
Press SEL to make cursor appear
so that values can be edited
Enter grid corner name, spacing,
and track direction – use large
knob to move cursor and small
knob to change values
ENTER
Press ENTER to accept values
ENTER
Press ENTER again to activate the
search pattern
PAT
Press PAT to cancel search pattern
Programming the Creeping Line
Search Pattern


Remember that direction entered is MAGNETIC (i.e.
based on the magnetic variation information that the
GPS unit has for the area)
Note that GPS doesn’t provide means to enter a
stopping condition (i.e. number of legs); it just keeps on
going…
–
You will need to choose a way to identify the end of the search
pattern; perhaps by watching latitude and longitude
Programming the Creeping Line
Search Pattern
MAP
Press MAP to view map pages
Turn large knob to view SAR map
page
PAT
Press the PAT smart key
Turn the small knob to view the
“Creeping Line Search Page”
ENTER
Press ENTER to begin
Programming the Creeping Line
Search Pattern
SEL
ENTER
Press SEL to make cursor appear so
that values can be edited.
You will see the cursor flash “Ins?” – it
is asking whether you wish to insert a
waypoint as the starting position for the
search. Press ENTER to indicate “yes”.
Enter waypoint information – use large
knob to move cursor and small knob to
change values
ENTER
Press ENTER to accept waypoint
Programming the Creeping Line
Search Pattern
You will now be back at the creeping
line value page with the starting
waypoint selected; enter the spacing
and direction for the search – use the
large knob to move the cursor and the
small knob to change values
ENTER
Press ENTER to accept values
A diamond appears on the page
indicating that there is additional
information that can be reached by
turning the small knob. (While we had a
cursor flashing we could not get to that
other page because the small knob has
a different job when we have a cursor.)
Programming the Creeping Line
Search Pattern
Turn the small knob to see the second
page of creeping line pattern values
SEL
Press SEL to make a cursor appear so
that values can be edited
Enter leg length and starting direction
(left or right) – use large knob to move
cursor and small knob to change values
ENTER
Press ENTER to accept values
ENTER
Press ENTER again to activate the
search pattern
PAT
Press PAT to cancel search pattern
Flying to Pattern Entry

Problem: The GPS unit sets up search
patterns as temporary flight plans; it recognizes
if you have already “passed” a waypoint and
immediately advances to the next one
–
This means that if you program the pattern while at
the wrong end of the pattern, it will jump ahead to
the nearest waypoint to you – and you will not be
guided to a correct entry into the pattern, and some
legs will be skipped.
Flying to Pattern Entry

Solution: Make sure the starting waypoint is the
closest waypoint to you when to finish entering
the search pattern program into the GPS
–
For parallel line (grid) searches, be sure to program
the GPS while outside the entry-corner of the grid
Flying to Pattern Entry
Enter program for
search pattern here;
Starting waypoint is
closest
Do not program
search pattern here;
several legs will get
skipped
Flying to Pattern Entry
–
For creeping line searches, program the GPS
outside the search area, on the centerline, just
outside the starting waypoint
Flying to Pattern Entry
Direction
Do not program
search pattern here;
several legs will get
skipped
Enter program for
search pattern here;
Starting waypoint is
closest
Starting
Waypoint
Flying to Pattern Entry
–
For expanding square searches, begin
programming the GPS near the starting waypoint;
delay finishing the programming until arriving at the
starting waypoint
Some Tasks We Haven’t Covered
That You Should Know for SAR/HS/DR


Entering User Waypoints into the Database
Using US Grid identifiers
Programming and using parallel track offsets
Consult the GX-55 “shorthand guide” for further information
Part 5 –
Safety Issues




User-interface tunnel vision
Over-reliance on GPS can be a trap
IFR usage issues
Other concerns
User-Interface Tunnel Vision

The GPS user interfaces are complex and draw your
attention into the box and away from the business of
flying the airplane
–
–
–
Some operations involve several steps and quite a bit of
thinking even if you are an expert using the device
Maintaining “situational awareness” is extra-challenging
Division of attention is critical


Traffic, terrain, and obstructions*
Altitude and heading*
* Especially at search-altitude

Another pilot or a well-trained crew member can be a
big help!
User-Interface Tunnel Vision
Remember your priorities:
1.
2.
3.
Aviate
Navigate
Communicate
Operating the GPS is secondary to flying the airplane
Note: The airplane flies because of Bernoulli, not Marconi!
Over-reliance Trap


Don’t be one transistor away from being lost
Use in conjunction with current charts and maintain
navigational situation awareness
–
–
–
–
–
–
Safe altitude (terrain and obstructions)
Restricted and Prohibited Airspace and TFRs
Class B, C, and D airspace
Wildlife management areas
Airports (and CTAF frequencies)
MOAs and MTRs
IFR Usage Issues

Not all GPS units are approved for IFR
–
–

Some GPS units are approved for IFR en route only
–



Must be IFR approved equipment
Must be permanent IFR-approved installation
But they cannot be used as the sole means of navigation
All Minnesota Wing aircraft GX-55 GPS units are placarded
“VFR Only”
Should maintain current database subscription ($)
Don’t underestimate the need for training
–
–
–
IFR usage is complex and outside the scope of this course
Each GPS device has its own unique user interface
Some sources suggest at least 40 hours of GPS training before using
GPS approaches under IFR
Other Concerns

Errors easy when
entering waypoint data
–
–
Airport and VOR
waypoints often have
same identifier even when
not co-located (example:
AXN)
Waypoints and stations
that are near each other
may not be exactly colocated
(example MSP)
Other concerns

GPS can be subject to accidental and intentional
interference
–
–

Easily jammed using strategically placed low-power
transmitters
WAAS is also at risk
Selective Availability (SA) or SCATANA could be
instituted during a national emergency
(but this is unlikely)
–
Current plan calls for possible use of “Selective Denial” where
GPS is degraded or denied to specific geographic areas
Part 6 –
Using the GX-55 Simulator



Tips for getting started
Bugs and limitations
How to find the simulator and
more information
The GX-55 Simulator:
Tips for Getting Started

The first time you run the simulator, you may
be surprised at your initial location, off the
coast of Africa at 0 degrees latitude, 0 degrees
longitude!
–
To put yourself someplace more familiar, enter any
flight plan and you will be whisked away (at warp
speed) to the first waypoint of your flight plan
The GX-55 Simulator:
Tips for Getting Started

Before “turning on” the simulator, don’t forget
to enable “SAR” using the application’s
“Options” menu
–
This is analogous to
the avionics shop
enabling the SAR
features on the
real device
The GX-55 Simulator:
Tips for Getting Started



“Turn-on” the simulator by clicking the “on-off” button
pictured in the simulator window
To press GPS buttons, click on them with your mouse
To turn GPS knobs, point at the knob with your mouse,
and then right-click to turn the knob clockwise and leftclick to turn counter-clockwise.
–
Aim carefully; the large knob and the small knob are very close
to each other
The GX-55 Simulator:
Bugs and Limitations

It is not possible to practice following a course
–
The simulator never allows you to go off-course and
observe a CDI deflection



Enter any flight plan or search pattern and it will send you
immediately to the first waypoint
The simulator will then follow the flight plan perfectly
There is no way to practice arrival into a search
pattern
The GX-55 Simulator:
Bugs and Limitations


Unlike the real device, the simulator is doesn’t care
where you are when you program a search pattern
The real device, when performing a multi-leg flight plan
or search pattern, gives you turning-arc lines
–

The simulator doesn’t, but instead gives instantaneous [warp
speed] pivots at each waypoint
The implementation of the creeping line search is
completely wrong in the simulator
–
The user interface isn’t even the same as in the real device
How to Find the Simulator
and More Information

GX-55 documentation and simulator
http://www.garmin.com/products/gx55/
http://www8.garmin.com/include/gxsimulator/SimulatorPopupGX.html

Other resources
–
The Minnesota Wing CAP GX-55 “shorthand guide”
http://www.mncap.org/es/reference_aircrew.cfm
–
General information about GPS
http://www.garmin.com/aboutGPS/
–
GPS Safety information
http://www.aopa.org/asf/publications/sa01.pdf
–
Detailed information
http://www.navcen.uscg.gov/gps/geninfo/