1. Missed weather window
Many of the climbers began gathering at Everest base camp at the start of May. At the same time, the authorities were concerned about the knock-on effects of Cyclone Fani which had already struck India and Bangladesh. The weather deteriorated in the Nepalese Himalayas days after the cyclone, forcing the government to suspend all mountaineering activities for at least two days.
Prolonged bad weather meant that the practice of fixing bolted rope to assist climbers trying to reach the summit was delayed. Meanwhile the crowd at base camp continued to build. After the ropes were fixed by mid-May, the first feasible clear-weather window was 19 and 20 May.
But only a few teams chose to climb then while the majority waited for the second window - from 22 to 24 May. Mountaineering experts say this was when the crowd management went wrong.
2. 'Bad crowd-management'
23 May saw the maximum number of climbers on one day - more than 250.
Climbers had to wait for hours below the summit - both on the way up and on the way down. Many of them were exhausted and their oxygen cylinders were running low.
Nepal's mountaineering regulation requires expedition teams to have liaison officers on the mountains. This time 59 of them were appointed to accompany the teams but only five of them stayed until the final part of the climb. Some did not even turn up, while most of those who did went home after a few days at the base camp. If all the liaison officials had stayed on the mountain, managing the crowd would have been much easier.
3. Inexperienced climbers
Mountaineering experts say there is also an increase in the number of inexperienced climbers joining the growing crowd on Everest. This time round, many of them had just one Sherpa guide with their team, officials at the base camp said.
Veteran climbers have long suggested Nepal's government should introduce certain criteria, including mandatory experience of having climbed peaks above 6,000m, for issuing Everest climbing permits.
4. Competition between operators
The quest to get anyone willing to pay has been mainly down to intense competition between operators, particularly old and new ones. With the entry of new expedition operators offering cheaper prices, mountaineers say even some of the established ones have been forced to cut their fees.
"Unfortunately the competition is for volume and not for quality." said Tshering Pande Bhote, vice president of Nepal National Mountain Guides Association.
Expedition operators admit there are problems but they argue they also need to increase the number of visitors for the growth of the industry.
"Next year, for example, is Visit Nepal Year (a mega-tourism campaign that aims to bring in two million tourists)," says Dambar Parajuli, president of the Expedition Operators Association of Nepal."