Terrain visibility analysis

Can you see Säntis from the Irchel Tower?

Short answer: Yes, in the terrain model. From the Irchel Tower’s observation platform, 28 m above ground, the reference summit of Säntis is visible over 63.4 km, with high model confidence and a summit margin of about +1,073 m. A further 1.7 m is allowed for the observer’s eyes, giving 29.7 m above the DEM. Clouds, haze and nearby structures can still obscure the view.

Säntis from the Irchel Tower: a 63.4 km terrain profile from the platform 28 m above ground, with eye height, coordinates and viewing limits.

View the calculation in Sightelo

Key figures

Observation point: Irchel Tower observation platform, Buch am Irchel, Switzerland; Latitude, longitude: 47.540552171428565, 8.62048237142857; Modelled ground elevation: 665.0 m; Eye height: 29.7 m
Point of interest: Säntis reference summit, Switzerland
Target elevation: 2,502 m
Straight-line distance: 63.4 km
Direction to the summit: 120.4° (east-southeast)
Modelled summit clearance: +1,073 m

Terrain profile and line of sight

Detailed profile

Scroll horizontally to explore the full profile on a small screen.

Calculated terrain
Observer–summit sight line
Minimum visibility line
Elevation reference: 0 m

Terrain already includes modelled curvature and refraction (k = 0.13). The grey curve projects a constant elevation of 0 m using that model; it is not an observed sea level. Subtract it from the terrain curve to read elevation. Sight lines remain straight; no second curvature correction is applied. Vertical and horizontal scales differ.

At the summit, the target clears the modelled horizon by 1072.9 m. No blocking terrain is calculated. The relief forming the horizon is 61.242 km from A.

The calculation models terrain, Earth curvature and standard atmospheric refraction. It does not model buildings, trees, clouds, haze or local atmospheric variations.

Calculated profile values

Distance (km)	63.4 km
Observer eye altitude	694.7 m
Summit altitude	2502.0 m
Minimum visible target altitude	1429.1 m
Target margin above the modelled horizon	+1072.9 m
Minimum local sight-line clearance	+61.9 m
Displayed / calculated samples	498 / 636
Excluded around A / B	200 m / 1500 m
Horizon-forming relief	61.2421 km

Audited calculation: 2026-10-23. The interactive calculator can recalculate with currently available elevation data.

What the raised platform changes

The 28 m platform height is documented by regional tourism and Swiss Hiking. It is not the tower’s total construction height. The coordinates represent its mapped footprint, not a measured eye position. The sight line heads east-southeast towards the fixed 2,502 m Säntis summit reference. The summit margin is the target elevation minus the minimum elevation needed to clear the modelled terrain horizon: about +1,073 m. Minimum local clearance along the ray is about 62 m, a different quantity. The DEM surface at the observer is about 665.0 m; the eyes are therefore about 694.7 m above the vertical reference.

Platform, ground and the real view

A verified comparison at the same coordinates with eyes 1.7 m above ground is also visible in the terrain model. Raising the observer does not reverse the verdict. That does not prove a clear view between trees at ground level. Stair access and current opening conditions are not guaranteed. Railings, antennas and vegetation are not individually resolved. The model includes Earth curvature and standard atmospheric refraction, k = 0.13. The grey curve projects a constant 0 m elevation; it is not a measured sea surface. Official swisstopo profile samples corroborate the cleared horizon, but use a different sampling scheme and vertical reference, without the same lateral corridor.

Technical details

Observation point coordinates: 47.540552171428565, 8.62048237142857
Summit coordinates: 47.249444, 9.343241
Terrain model: Copernicus DEM 90
Eye height: 29.7 m
Refraction used: Standard (k = 0.13)
Sample step: 100 m
Uncertainty threshold: 30 m
Observer exclusion radius: 200 m
Requested summit exclusion radius: 600 m

A positive value means the summit clears the modelled terrain horizon. A negative value means the summit lies below the minimum elevation required to clear that horizon. This value is not the local height of blocking terrain above the sight line.