Orange: from here you could see the North Front runway. Blue-grey: you could not.
The ground is a 4 m grid of today's bare earth, merged from the HM Government of Gibraltar elevation model, Spanish IGN PNOA-LiDAR and Copernicus GLO-30. Buildings, trees and wartime structures are not in it.
For every land cell, a sightline runs from 1.5 m above the ground to points every 20 m along the runway centreline, 1 m above the runway, allowing for the curve of the Earth and normal refraction. 2,996 of 3,000 random checks against an exact sightline test agreed.
The runway grew west into the Bay. Its east end is taken as today's, and each stage is measured west from it: 1,150 yd by April 1942, 1,550 yd by November 1942 and 1,800 yd by July 1943. The stage ends are approximate.
Share of each part of the Rock (above 30 m) that could see at least some of the runway, and at least a quarter of it:
| Apr 42 | Nov 42 | Jul 43 | |
|---|---|---|---|
| North end | 70% · 53% | 84% · 68% | 88% · 75% |
| West side | 18% · 0% | 52% · 19% | 79% · 31% |
| East side | 6% · 0% | 6% · 1% | 7% · 1% |
| South | 0% · 0% | 2% · 0% | 4% · 1% |
| Whole Rock | 17% · 6% | 34% · 16% | 46% · 22% |
The north face above the Great Siege Tunnels saw all of it. The west side mostly saw the new western end out in the Bay. The east side and the south were almost blind to it. The cave site near the summit saw none of it at any stage.
Data: data-sources.json · llms.txt
In 1942 the airstrip at North Front was being pushed west into the Bay, while inside the Rock Operation Tracer was secretly fitting out a hidden observation post. From where on the Rock could you actually see that runway? This map colours every slope: orange where you could see it, blue-grey where you could not.
It is a 4 m model of today's bare ground, with no buildings or trees. Click anywhere to test the view from there, switch between the runway of April 1942, November 1942 and July 1943, and hatch areas to rule them out of a search. Your marks can be saved and loaded as a file.
Sources and method: llms.txt · data-sources.json