Lukla airstrip, the last runway towards Mount Everest, and regarded as the most dangerous airport in the world at 2,845m. Built in 1964 with an arrival incline of 11.7 degrees, the strip services the immediate Everest region as a vital refuelling point for helicopters heading onwards and further upwards in altitude to EBC.
Captain Kiran Pun has been flying Nepal's mountain routes since 1995.
'Some places you fly to all the time so you know what to expect. But you have to be ready to change course quickly if the weather changes for the worse. If you can't see, then you can't fly. It's not safe. It's the same for rescue missions.’
Nepal's landscape is known for its layers of rice terraces, carved and stacked around mountain contours by generations of farmers.
'They're beautiful to see from the air,' says Captain Pun. 'They're important for growing rice and corn, but they can collapse and cause landslides in the monsoon season when the heavy rains come. It's a problem that's becoming more of a worry.'
Scientists say Nepal's glaciers are melting at significantly faster rates than recorded previous decades, contributing to an increase in cloud cover and rainfall over the Himalayas.
For the pilots, this requires them to be comfortable navigating sudden changes in extreme weather while also staying safely clear of invisible mountain peaks.
On final approach to Everest Base Camp, pilots fly low over the tongue of the Khumbu Glacier that carves through the mountain’s bedrock. Hugging the glacier allows pilots a close-up inspection of the ice's health, which recent core samples found to be several degrees warmer than expected.
Rescue workers who live in the valley say the most visible changes are a drop in elevation along the middle of the glacier and the growth of glacial ponds. Ice still lies below the dark blanket of rocky deposits, but the moraine has an insulating effect and absorbs more solar radiation than snow, accelerating the rate of ice depletion below.
Everest Base Camp stretches for several hundred metres along the edge of the Khumbu Glacier, which itself is in a state of retreat.
'The height of the ice is lower now than 10 years ago. It's very visible,' says Captain Pun.
'Maybe you last flew there a few months ago, but now there's boulders in the ice you've never seen before. We know from scientists they've been melting for about 50 years but they say it's been melting even faster these past 20 to 30 years.’
Banking towards Pheriche Aid Post, Captain Pun brings into view a braided river channel, widened by floodwaters. A ruptured glacial pond can release millions of cubic litres into the valley, and the sudden run-off of water can have devastating effects down the mountain
A warming climate increases the chance of an avalanche or icefall, particularly where glaciers curl over a cliff edge. First aid responder Sudip Lingthep says it has become more frequent since his first Base Camp visit in 2008.
'In winter, there can be two avalanches a day on average,' he says. 'In some regions, I always take the alternative trails. It's important we make sure people know the risks.'
The increase in glacial meltwater also contributes to the triggering of landslides. 'Looking back to 2008, I feel like I was walking on higher ground,' recalls Sudip. 'There's a lot more landslides now because of the rain. Sometimes you can hear the ground moving beneath your feet. It can be very strange when you trek through an area you know very well and the ground is different.'
Parts of Kathmandu Valley experience heavy flooding during the annual monsoon season, impeding the lives of more than a million Nepalis. Although much of the valley itself has drainage capable of coping with excess mountain run-off, there's a growing concern over how much can be mitigated as rainfall increases and the glaciers continue to melt.