Part IV : The Western Breach
Also known as the "Great" Western Breach, this feature exists due to a massive collapse of part of the summit of Kilimanjaro at some point the geologic past. This collapse also formed the Barranco Gorge.
The Western Breach is a steep slope that cuts through the steep south aspect of the mountain. It is perhaps 1 kilometre wide, and about 1.25 km horizontally from base to top. I estimate the slope at about 30 to 40 degrees through, with the steeper part at the top.
The lower part of the Breach is sloped talus. The upper part has a a series of horizontal cliffs with "breaks" in them. The route up winds around and through these breaks in the upper cliffs. Above these cliffs is the rim of the main crater (the main crater is called 'Kibo').
The lower part of the Breach is just above the Arrow Glacier camp, at about 16,200 feet. The upper part of the Breach, right at the rim, is at about 18,700 feet. Total height: about 2,500 feet.
I've seen the Western Breach described as everything from an easy scramble to a death-defying, climbers-only route. In my opinion, it is neither. It is true that you must have a reasonable comfortable with heights, because it is fairly steep and, higher up, there are some moderately exposed areas when you are winding around on the cliffs. On the upper portions, you will definitely have to use your hands in several places. However, the vast majority of the ascent is on a steep talus trail. I would recommend bringing an ice ax and crampons on this route if it looks at all snowy or icy. If the Western Breach looks only moderately snowy/icy, then you probably will not need to use them (most guides don't bring them!). However, safety is paramount and it is the prudent thing to do! Oh, and... if you don't know how to properly handle an ice ax or crampons, please practice proper technique somewhere _before_ you get to the mountain!
Below are some more annotated pictures, showing the Western Breach from different aspects. This should help you get a good 3d-impression of what it is like.
On the next page is the description of the climb from Arrow Glacier up the Western Breach, and from there onto the summit.