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16.3. Following a route in detail

Here is what happens when you decide to follow a route with a app.

First waypoint (and approaching second)

Approaching second waypoint

Starting at the first point on the route the navigation arrow will point at the second point. As long as you stay on route, that is you don't trigger the cross track error alarm, the navigation arrow will continue to point at the second waypoint.

Arriving at second waypoint

Arriving second waypoint

When you reach the grey outer circle, the arrival alarm will trigger. The navigation arrow will turn red, but it will still point at the second waypoint.

Reaching second waypoint

At second waypoint

When you reach the red inner circle you are considered to have arrived at the second waypoint. This waypoint is marked as achieved and won't be targeted again. The navigation arrow will now point at the third waypoint. The arrival alarm continues to sound until you pass the current waypoint - that is you are closer to the next leg of the route.

Toward third waypoint

Toward thrid waypoint

You are now navigated to the third waypoint. Once you have arrived at a waypoint that waypoint is marked as achieved. ViewRanger won't consider that waypoint again, or any before it. However, you can override that with menu commands. Even if you now go backwards towards waypoint 1 the navigation arrow will still point at waypoint 3. You can however change this by choosing Options > Navigation > Step target backwards.

Detail of what happens as you reach the waypoint

As you reach the waypoint there are two target distances involved.

The navigation arrow points to the next waypoint. In the diagram below, as you go from waypoint number 1 to waypoint 2, the arrow points towards waypoint 2.

When you reach the arrival alarm distance, the pink outer circle, the arrival alarm will sound if you have it enabled.

The distance given by Settings > Navigation > Show next wpt distance controls the distance at which ViewRanger will consider you to have arrived at a waypoint. It is shown as the inner yellow circle in the diagram below. Once you reach this distance from a waypoint, the navigation arrow will start pointing to the following waypoint. So in the diagram, when you reach the inner circle the navigation arrow will start pointing at waypoint 3. Its default value is 15m.

If you have alarms enabled, the arrow will still be red while you are within the alarm distance.

Going off route

If you go off route by more than the cross track distance, ViewRanger will re-evaluate where you are.

If it finds that you are closer to a later leg of the route it will direct you along that leg. It gives preference to the earlier route legs. However, if you return to your route it will revert to directing you to the next waypoint.

It will never consider route legs prior to a waypoint that you passed through and was marked as achieved, as long as that waypoint was achieved in correct order.

Route Navigation Troubleshooting

The most important setting is the Show next wpt distance. This defaults to 15 metres. If you find that the navigation arrow points to the subsequent waypoint too soon then reduce this setting. If you find the navigation arrow pointing backwards as you pass the waypoint then increase the value. On a 1:50,000 scale map 15 metres is a circle 6 pixels across and on a 1:25,000 scale map it is 12 pixels across.

The cross track error distance is also important. For example, if you short cut a corner the navigation arrow will point at the waypoint you are missing until you are more than the cross track distance off the route. So if you often short cut corners, keep the cross track error distance quite low.

The arrival alarm distance only determines when the arrival alarm starts sounding. Normally you want the alarm to sound as you approach a waypoint, so keep this setting greater than the next waypoint distance.

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