GPS Check List
1. Before the task is set
- GPS acquired (day before if you travelled to another country).
- Waypoints entered (if at all possible get them from the scoring PC).
- Track log setup, track log on, suitable time interval, do you want to WRAP or FILL?
- Track cleared from previous day.
- Clock set to local time.
- Appropriate maps loaded (if applicable)
- Map scaled usefully, North up, rings on if applicable.
- route setup - off road transition set to 400m or less if you are lucky enough to have this setting.
2. When the Task is Set
- All waypoints entered in correct order as a route.
- You are familiar with how to avoid a premature automatic switch, or how to deal with one!
- You know when you may leave/enter the start circle.
- You know when the land by time is.
- Write the waypoint names and order where you can see them in case of a serious GPS malfunction.
- Draw the course shape where you can see it so you know roughly the direction of the next waypoint after the current one.
- If the last leg is short, work out an altitude to get to the last turnpoint, so you can do final glide before the last turnpoint.
- Clear track log.
- Do you want the start, or the first waypoint on the goto screen?
- Calculate the distance from the first turnpoint that the edge of the start circle will be (so you can fly with the first turnpoint on screen and stay inside the start circle).
- Work out the direction of the first turnpoint so you can be in the right place when flying with the start on the goto screen.
- Can you get the time and the goto on the same screen or do you want to see your (synchronized) watch as well?
- Can you work your GPS with those gloves on? (Tip: make a small slit on the inside bend of the thumb of your glove. You can get your thumb out by biting the end of the thumb of your glove. The slit is closed when gripping the bar. This works really well!)
4. After takeoff
- Do not set off on course before the first start (minimum distance points!)you can go back into the start circle to get a later start.
- See the track log on the map screen. If it is not there you have no tracklog!
- Regularly report your position and altitude. The simplest way is to call in your distance to the next turnpoint, and your distance left or right of track (Cross track, xtrack on the GPS). This is simple for everyone to understand.
e.g. "Joes Bloggs 16 km from tunrpoint 2, 5000ft, 1.5 km left of track".
5. On course
- Do you know what to you are going to do if your GPS switches to the next turnpont before you get to the current turnpoint!
- if the turnpoint has an odd radius, bigger then 400m, can you get your GPS to switch to the next?
- Don’t fly too far-go to the edge of the circle nearest the next turnpoint!
- Make sure you are inside the circle long enough to get a point.
- Do you know how high you need to be X km from the finish?
6. At the end of the RACE (Not at the turnpoint)
- Fly fast and straight through the finish until you are sure you have a few points past the finish line, then you can slow up.
- After landing switch off GPS before the track log can wrap, if applicable.
- Make sure your track log is safe when using the GPS to find others.
8. At base
- Get in the GPS queue before it gets too long
- Put your GPS somewhere you can get at it to go to score. The bottom of a harness at the bottom of a heap of harnesses in the bottom of the car boot is not the best place. You could be scored, food ordered, beer in hand before the others dig out their GPSs!
- Try not to be too loud talking in the GPS queue! ie avoid the likes of Johnny Carr, Gordon Rigg and anyone with a Scouse accent!
1a A gps that has moved a long way from its last recorded position may take
a while to find itself, perhaps longer then if it were new out of the box. Older
GPS are worse. Some types let you tell them roughly where they are to save
time. If you travelled a long way, don’t leave it to the last minute to switch
on or you might find the window is open and others are flying before your
GPS has a position!
1b Entering waypoints.
The waypoints are defined with reference to the map datum (WGS84 while
abroad, OS grid in the UK). They are then displayed in a particular number
format. UK comps will attempt to always use the same format for the UK
(OS grid) and abroad (degrees and decimal minutes). This allows MLR and
Garmin users to set the waypoint with the same accuracy.
Wayponts that come out of the computer are always at the correct position
no matter how you set the datum, and format on Garmin GPSs (not
necessarily on MLRs and Compeos!). If you have a different datum/format
set after the download then you will see different numbers for the
turnpoint, but when you stand in the same position you will have the same
distance from the tunpoint as the next guy - and it will take you to the same
If you have to enter a new turnpoint by pushing buttons on the GPS you
must have the right datum and position format set before hand or the
position you enter will be wrong - wrong by more than enough to miss a
2a By entering the waypoints as a route you will get a distance for the course
that you can compare to the task board and other pilots. Check this is
correct every time. Ask for help if you can’t get it to agree. Particularly
important if you had to enter a waypoint manually.
The route allows you to progress from one waypoint to the next easily - but
there can be problems.
2b Garmin very cleverly came up with an automatic switching from the current
waypoint to the next waypoint which is extremely annoying for us. If while
heading to A on the way to B you fly a path that goes toward B then the
Garmin will "helpfully" assume that you aren’t bothering with A and start
pointing toward B. This will happen all the time when you are circling close
to the waypoint, and the path is like an out and return. If you switch it back
again to the desired waypoint it can easily switch again before time. This is
the single thing that cost more missed turnpoints with GPS than anything
Most pilots fly with the road or compass screen and follow the arrow until
we get less than 400m to go. Then suddenly 1km out it says 25km to the
next place, but did we get the turnpoint? Who knows!?
There are several approaches to solve this:
Some pilots faced with this switch to the map screen and fly until their trace
is close enough to the desired waypoint. Some GPS allow rings about the
current position and if the scale is set suitably the ring may be the right size
for the 400m radius so they fly until the waypoint is inside the ring and then
set off to the next turnpoint.
My way is to not activate the route but use the single stored route as a way
to access each waypoint in turn. By moving the cursor down the list of
waypoints in the route you can then press goto and you get the selected
waypoint. Thus I get a series of goto’s which can’t switch in advance.
Combined with my drawing of the route shape I can thus set off in the right
direction and have plenty of time for the several buttion presses required to
get ojnto the next point.
You can also select the desired waypoint on the map screen and hit goto.
This goto will overide the route so shouldn’t switch.
MLR users don’t have this problem. Some of the newer Garmins have a
manual route progression or switch on distance because they finally did
listen in the end!
5b. If you point directly at the waypoint centre you may be flying too far and
putting yourself down wind of the best position. Aim to just fly into the edge
of the 400m circle for the shortest line to the next waypoint, allow for the
5c. You need to record a point in the circle, or the line between two recorded
points must cut the circle.
6a. The scoring program works out when you actually crossed the line by
looking at the average speed between the lastpoint outside and the first
point inside the finish. So slowing down immediately you cross will give a
slower time than the guy just behind you who carried on at 120km/hr past
you! Yuo need to carry on fast for whatever interval of time you have in the
Suggested track log intervals:
GPS12/12XL - 15 or 20 seconds (1050 points?)
GPS12MAP - 10-12 seconds (2000 points)
MLR Vol Libre - 5 seconds (1 isn’t enough time and it wont do 3 unless you
have the secret french software!).
New GPSs have lots of track log points and should allow a setting like 3
seconds, and they also send them to the PC faster too!
MLR OS grid number vs letter crib sheet.
The French couldn’t understand the letters in the OS grid system so to put
an OS grid ref into an MLR you need to know the numbers that correspond
to the grid letters as illustrated here. Print this and keep it with your MLR!