By October 10, Mick Fowler and I were running out of time. We had ruled out the east (not accessible from our base camp), the west (too dangerous), and the south (too long) sides of unclimbed Chombu (6,360m). This left just the north face, by a line we had identified as the northeast spur. The face looked accessible from a glacier flowing to the Sebu Cho on the Lanchung Valley (east) side of Chombu. The question was whether we could reach this glacier from the west.

A short exploration in the usual bad weather revealed an approach over moraines to a 400m couloir on the watershed ridge between the Lasha Chu valley (west) and Sebu Cho valley (east side). What we could not know was if the couloir, which we now dubbed the "Fowler Couloir," would give us access to the North Chombu Glacier or if, after climbing the couloir, we would be faced with a problematic descent to a glacier hidden from view.

We already had made one trip to northeast Sikkim, in the spring, hoping to climb the attractive west face of Chombu (27°53'54.47"N, 88°38'40.37"E), but had been shut down on the West Chombu Glacier by bad weather and unstable snow conditions. We reasoned it could not be as bad in the post-monsoon season. We were only partly wrong.

On October 11, making a predawn start, we trekked up the moraines and boulder fields leading to the Fowler Couloir. We had run out of exploration time, and this would be our one chance to get to grips with the mountain. We were in luck: At the top of the couloir, we stepped off the watershed ridge and onto the North Chombu Glacier. The following morning was foggy. We waited till the sun burned off the cloud, enabling us to see a good route through the long, wide crevasses that guard the base of the north face. The snow became deeper as we approached the face; the glacier, shaded from the sun, lacked the melt-freeze cycle necessary for a firm surface.

On day three the task of climbing began. First there were bottomless snow flutings with no possibility of ice screws or other protection till we were in reach of the northeast spur. After that the climbing continued with deep, cold, unconsolidated snow over rock. Looking up, the route appeared to be pure snow climbing, but after the leader had cleaned the pitch to reveal the bluffs and outcrops in search of elusive runners, it looked rocky. While trying to traverse snow-covered slabs, I took a 20m fall. Fowler was persuaded to lead the next few pitches while I recovered composure. The bivouac was on a fine narrow ridge, belayed to a large boulder. With the change to good weather, the temperature also dropped, and it became very cold at night.

Day four was short but demanding. The crux of the route passed though steep, snow-covered buttresses before breaking out onto a relatively low-angle shoulder leading to the north summit of Chombu. Most pitches were physically exhausting, with the added psychological uncertainty of the unconsolidated snow, sparse runners, and potentially big falls. Our bivouac at 6,107m was barely 250m of moderate climbing below the summit. In the snow conditions we were experiencing, and with the horizontal distance involved, we estimated it would take us another day and a half.

During that night we shared a package of dried food: "Beef Stroganoff with Noodles." It tasted strange, a bit like oxidized linseed oil, but we knew we would need the energy for the next day. This was a mistake. A bad mistake. By the morning we both had been so sick overnight there was no option but to descend. We were not able to eat again for two days.

Days five and six were spent reversing our route, the rappels revealing the seriousness of the climbing. We left base camp four days later, trekking out in heavy snow. The weather had been consistently poor for most of our time in the area, with rain and snow through much of the day. Temperatures were warm, suggesting the monsoon had not yet left Sikkim. The change that came on the 11th, as we started up the mountain, probably marked the end of the monsoon. Around one week later, the first winter snows arrived, leaving a short window of about one week. It's not clear there is a "best" season to climb this mountain.

Sikkim weather is best summarized by a note from Julie-Ann Clyma, who visited the area in 2007: "Just how much uncertainty can you take?"

– Victor Saunders, France