Cuolma

Cuolma is a planning app for high-alpine tours.

It opens a GPX file and lays the line on the terrain and aerial imagery of swisstopo, at the finest resolution swisstopo publishes: terrain down to half a metre, imagery down to ten centimetres, twenty-five in the high Alps. Enough to pick out the gully beside the ridge, and the step in the face, before you are standing under it. It works without a file too: a coordinate or a tap on the map, and the area is there.

It stays a model. The ground is a height field: it carries no overhangs, and on a steep face the image is stretched across it. A GPX line is only as accurate as the GPS that recorded it. Cuolma shows the mountain as closely as public Swiss data allows. That is not the same as showing it as it is.

MAP OR AERIAL IMAGE

A slider blends the National Map 1:10'000 of swisstopo over the terrain: all the way left the map with its contour lines, paths and names, all the way right the aerial image, in between the two through each other. Take the area offline and the map lies there with it, at the finest level.

TRAILS FROM SWISSTOPO

The hiking trails, ski and snowshoe routes of swisstopo come with the app, and the magnet lays your tour along them: you set the points that matter, and the line between them follows the trails. Off the trails you draw freely. A band in the profile shows which trail each stretch is on.

Cuolma does not check whether a trail can be walked today.

FOR THE PEOPLE WHO PLAN FOR OTHERS

Cuolma is made for tour leaders and rope leaders of the SAC, and the point is the quality of the planning. Find the key sections before the day. See what the ground does where the route gets serious. Work out a rough timetable with the 15-minute rule of the SAC, your start time, your pace and your breaks, and read it off for every place on the tour instead of only for the end. Cuolma also says how light it is when you arrive: night, twilight, shade or sun.

SLF AVALANCHE BULLETIN

Cuolma fetches the avalanche bulletin of the SLF and lays it onto the tour: the danger level, the avalanche problems and the sentences of the SLF, as the SLF issues them. What counts is the bulletin.

In the profile, Cuolma also marks which places on the tour match what the bulletin names, by steepness, aspect and elevation. That band Cuolma works out from the terrain itself, and the SLF has not checked it. Cuolma counts the ground under the tour from 30 degrees up, and not the slopes above it.

Cuolma shows the bulletin. It does not assess avalanche danger.

PLAN AT HOME, CHECK ON THE MOUNTAIN

Drawing fine terrain costs data and battery. Terrain and aerial image can each be turned back to two metres: then less goes over the air, and the battery lasts longer. Use Cuolma mainly before the tour. On the mountain, use it in short looks, or the battery will be gone before the day is. Cuolma shows how fast the battery is falling and says so before it gets tight.

OFFLINE

Load the area at home and Cuolma needs no network on the mountain.

SWITZERLAND AND LIECHTENSTEIN

The maps come from swisstopo and cover Switzerland and the Principality of Liechtenstein only.

A sample tour ships with the app: the north ridge of the Weissmies.

Cuolma is free and has no account.

It measures terrain and says how it measured. It makes no weather forecast, and its times contain no reserve. About snow it says only what stands in the bulletin of the SLF. It replaces no avalanche assessment. It carries the map, and the paper in your pack it still does not replace: a phone runs empty and gets wet.