The Lhotse face is a wall of rock-hard blue ice and hard packed snow and climbers typically climb it twice; once during the final acclimatisation climb and then again en route to the summit. This is a tough climb and requires great care and concentration as the steepness and hardness of the ice makes it difficult to get a grip with crampons. Due to this climbers must be clipped into the fixed line at all times, even when moving around Camp 3 which is cut into the face.
To enable movement up and down the mountain simultaneously there are usually two ropes attached with ice screws and anchors. Climbers are connected to a rope by a karabiner and a jumar, each attached the the climbers harness by a short length of rope. These devices must be unclipped in order to pass each anchor. It is critical that climbers only unclip one at a time, firstly moving the karabiner from the lower side of the anchor to the upper side and re-clipping before moving the jumar. By this means the climber is always connected to the fixed rope by at least one device. A jumar is a mechanical device through which the fixed line runs freely in one direction only. As each step is taken the climber pushes the jumar up the rope. A karabiner is a metal loop with a spring-loaded lockable gate. When reaching an anchor point the karabiner is moved above the anchor and re-clipped and locked. In the event that a climber’s footing is lost while the karabiner is unclipped then the jumar will grip the rope preventing the climber falling. Then the jumar is moved above the anchor. If footing is lost while the jumar is unclipped then the karabiner will hold at the anchor point again preventing the climber falling.
At busy times, typically if the weather window for a summit attempt is short, it is not unusual for a queue to develop. This is worsened if some slow climbers prevent faster climbers passing. Some climbers will inevitably be slower than others given that towards the bottom of the face and close to Camp 3 the angle can be in the order of 40 to 50 degrees.
Camp 3 is nominally at 7162m (23,500ft) but as it usually comprises tents on 2 or 3 levels, each flat area having been hacked out of the ice by the sherpas, there can be some distance between the highest and lowest tents. It typically takes 2 to 3 hours to complete the 2.8km (1.7 mile) distance, 762m (2,500ft) height gain, climb from Camp 2 to Camp 3. Of course it will take longer if there are queues.
Above Camp 3 the route to Camp 4 at the South Col crosses the Yellow Band and the Geneva Spur. While these are not technically difficult the initial steepness still presents a considerable challenge at this altitude. It would be normal to use oxygen from Camp 3.
While the climbing would usually begin after sunrise it will still be extremely cold before the sun moves over Lhotse, especially if the wind is strong. However once the sun appears and in cloudless skies, as was the case in the Western Cwm it can rapidly become very hot especially for climbers in full down suits.
The route from Camp 3 to Camp 4 may take from 3 to 6 hours depending on conditions and climbers’ capability. The height gain is 854m (2,800ft) and the distance is around 800m (2,625ft).
Camp 4 is notable as offering the first view of Everest’s summit, still over 800m (around 2,700ft) above, but climbers will also be acutely aware that they are now on the edge of the Death Zone where there is not enough oxygen for humans to breathe. While not every climber uses oxygen at the this height those who don’t are extremely rare.