We are on a Yeti Airways flight, just taken off from Kathmandu. In front of me sits a large old man in a woollen cardigan, his hair grey and tousled, his face as craggy as the mountains below. He is deep in thought.

Perhaps he's remembered that today is the anniversary of the saddest day of his life. The day his wife and youngest daughter took off from the very same airport and minutes later died. Or perhaps he's thinking of Everest. It has come into view now. A giant black pyramid above the clouds.

How strange that the planet's highest peak is almost exactly the right height: custom built by the gods just high enough to test human beings to their limit. At twice the height it would be impossible, at half the height inconsequential.

Fifty years ago, no one knew if it was possible to climb it. Many had tried, many had died. But in the early morning of 29 May 1953, two brave men worked their way along its virgin knife-edged summit ridge. On their backs were oxygen cylinders so heavy their weight almost cancelled out their advantage. On their minds, the scientist's warnings that if their oxygen cylinders stopped working, they would probably die.

One of these legendary heros, Tenzing Norgay, is long dead. The other sits in front of me, Edmund Hillary. Everest, that great event in his life, has faded from view now, and his face warms as the plane banks to reveal the terraced Sherpa villages. The ground rushes to meet us and we are bumping along a grassy airstrip well known to Hillary, he built it.

A huge crowd surges forward as Hillary pauses at the doorway of the plane to take in a lungful of thin air. But what the atmosphere lacks in oxygen it makes up for in affection. There is love in everyones eyes, welcome scarves and flowers. Soon Hillary is amongst them, embracing a doctor from a hospital he has built, a nurse from a health clinic he has built, a pupil from one of 30 schools he has built, and other players in his 40 years of secret service to the people of Everest. The man who climbed their highest mountain has gone on climbing higher into their hearts.

How he would have laughed if you'd told him his life would be like this. I have an image of him back in 1931 in his own rural setting, a bee farm out of Auckland. He is 12, short and scrawny, uncomfortable in his own body, uncomfortable amongst others. At school he prefers the company of the ants in the playground to his fellow pupils, and in the physical education class he has been placed in the hopeless squad.

The mountain people are leading him up a hill now, one of his oldest Sherpa friends supporting him by the arm, others poised to help should Hillary's 80-year-old body falter. For over 40 years they have watched him come to them, in the early years trekking for weeks from Kathmandu with hundreds of porters carrying building supplies. Now he comes by air and less often. But each visit is treasured. And each visit they know may be his last.

He is here to work. He and his team. One of his team is walking beside him, a bearded man with a twinkle in his eye, also about 80. He is George Lowe, the other New Zealander on that successful British Everest Expedition of 1953. If they'd had their way they would have climbed to the summit together but fate, or rather expedition politics, decreed otherwise. Not only did the leader John Hunt not countenance a colonial summit team upstaging the English team members. Hunt had even dropped them from the expedition some months prior to departure, but reinstated them after being persuaded quite prophetically by the English team members that Hillary and Lowe's alpine skills could well mean the difference between success and failure.

Some years after the successful climb, some Sherpa friends were sharing the fire with Hillary and Lowe when Hillary asked his head sherpa, "Urkein, if there was just one thing we could do for our Sherpa friends what would they want it to be?" The reply was immediate. "Sir, we would like a school for our children." Next year, Hillary and his team built a simple school in the Sherpa village of Khumjung and soon the first batch of eager barefoot Sherpa children, faces brightly polished for the occasion, stepped into their wooden benched classroom and began a journey that would take some to incredible heights.

When word spread through other villages and other valleys, Hillary was avalanched with petitions. At Thami village the monks and elders composed a petition that was presented to Hillary by a 10-year-old boy. They had written: " Our children have eyes but still they are blind. Please build a school in our village too." So next year Thami village, where Tenzing Norgay had grown up, had a school of its own.

Hillary and his teams have now built thirty schools, as well as two hospitals, two airstrips, many bridges and many health clinics. A forty year labour of love, fashioning rocks he used to climb into school and hospital walls, working with Sherpa and Western building teams, including his brother Rex who worked as building foreman on these projects for twenty five consecutive years.

Hillary is among friends. Ang Rita was in the first batch of children from Khumjung and went on to top the SLC. Now he is Hillary's right-hand man, the full time administrator of the Himalayan Trust. Hillary's son Peter is taking pictures, shuffling a little painfully having only recently returned from hauling a heavy sled uphill for 84 days to the South Pole.

Nothing's been too easy in life for Peter. As the son of the most famous New Zealander it's been hard for Peter to blossom as his own person in the giant shadow of his father. But he's stepped well out of that shadow now , followed his father's footsteps up Everest in 1990 and has recently followed his own footsteps to the summit of Everest again.

Peter was the first child born to Hillary and his wife Louise, whom Hillary had courted in Sydney where she was studying music. Two other children soon followed, daughters Sarah and Belinda. By then Hillary's building activities in Nepal were in full swing and it wasn't long before three little Hillary children were carrying rocks along with Sherpa children, each doing what they could. These family trips to Nepal, living and working with the Sherpa people, were the happiest times in Hillary's life, and 1975 was meant to be the happiest time of all.

That year Hillary, Louise and their now teenage children had decided to spend the entire year in Nepal. Hillary had gone on ahead to supervise the building of his second hospital and his family would join him in stages. His wife Louise and youngest daughter Belinda, 16, would be first in and on 31 March 1975 they set off with the family dog and some Sherpa friends to Kathmandu airport to fly in to join him. Louise had always been fearful of light planes and wanted to walk in, but Hillary had persuaded her to fly.

A young New Zealand pilot met them at the airport and soon they were taxiing for takeoff. Perhaps in the excitement of transporting half the Hillary family, the pilot had omitted one pre-flight check. He had forgotten to remove the pins that unlock the tail flaps. The plane took off, the tail flaps still locked in stall position. It came crashing down into a field killing all on board.

Hillary, standing on the mountain airstrip on which they should by now have landed, had a premonition that something terrible had happened, and a friend soon arrived by helicopter to break the dreadful news. Hillary helicoptered back to Kathmandu and felt compelled to land at the crash site. He would have nightmares for years to come.

That night Hillary cremated the two people he loved most in the world, his wife and youngest daughter. And his only wish that night was to join them. For days he struggled with inconsolable grief made worse by his belief that it was all his fault, that he'd made them fly rather than walk. His two remaining children, Peter and Sarah on arrival in Kathmandu were warned by their grandmother, "Your father will never be the same again. He's heavily drugged, curled up in a ball, sobbing."

It was the hardest thing that tough man ever did, clawing himself back from the brink of suicide. He would stay alive, he decided, for what was left of his family. He would stay alive because of his responsibilities to the Sherpa people. He would return to the hills and his half completed hospital, and work and weep with his Sherpa friends.
Hospital completed, Hillary returned to Auckland. The family house felt like an empty shell and he felt the same. As part of his self-healing he would throw himself into the organisation of an expedition he and his late wife had often talked of doing together, journeying by jetboat along the entire length of India's River Ganges.

It would prove an extraordinary expedition, in Hillary's opinion his most memorable ever. No expedition in history had ever been done in such public gaze. You could hardly see the Ganges banks for people, hundreds deep, here to catch a glimpse of these magic boats and the hero of Everest.

Hillary and his late wife Louise had had as closest friends Peter Mulgrew and his wife June. Peter had been on expeditions with Hillary in Antarctica and the Himalayas and they and their wives had been an inseparable foursome. But in 1979, four years after Louise's death, Peter Mulgrew died, also in an air crash. At the last moment he had taken Hillary's place as guest commentator on an Air New Zealand flight to Antarctica which crashed into Mount Erebus, killing all on board.

The foursome was now a twosome, and soon the twosome became one. In 1985, Hillary became New Zealand High Commissioner to India with June at his side. During these High Commission years Hillary could often be seen not on the cocktail circuit but high on a schoolhouse roof, sleeves rolled up banging in nails. And here they are in Nepal again, Sir Edmund and June, Lady Hillary. Now long married and now long associated in this work in Nepal, they sit together listening to petitions from red-robed monks have come with photos of their distant monastery and are seeking support to enlarge its courtyard.

he children of the Phaplu primary school, their dusty red school uniforms held together by an equal measure of buttons and safety pins, are not just carrying schoolbooks today. Each child has a beautiful arrangement of red rhododendrons for Edmund Hillary.

The teachers form the children into a line that stretches from the school almost to Hillary's hotel. Hillary makes his way along the line of beaming children, each one handing him their own little gift of thanks, the flowers from their forest. At the school Hillary and his party are led through various rooms. George Lowe, on retirement as Her Majesty's Inspector of Schools in the UK, travelled incognito around all the Hillary schools and recommended curriculum development. The results have been spectacular. The team of Hillary and Lowe (Hillary building schools, Lowe supervising teaching standards) has pulled off something special, just as they did in 1953.

After the summit team of Tom Bourdillon and Charles Evans gave up at the South Summit on 26 May, it was Hillary and Tenzing's turn. They had a three man team to help them establish a higher camp: Ang Nyima, Alf Gregory and George Lowe. It was Lowe who cut the steps to the highest camp, carrying the most, and putting up Hillary and Tenzing's tent. They discuss whether Lowe should stay with them for tomorrow's summit push, for a three man team may be valuable if the route proves very technical. But there is insufficient oxygen for three. Lowe wishes them well and walks downhill into obscurity.

Next morning Hillary and Tenzing set off for the summit. Snow conditions are dangerous. Slopes could avalanche, and on any other mountain they would have turned back. But nothing will stop these men, not the danger, not their pitiful oxygen supply, not the steep, jagged, endless summit ridge. At 11.30 am on 29 May, two brave men from the fringes of world society embraced on the roof of the world.

The entire team flew to London, and the New Zealanders Hillary and Lowe for months bemusedly shared a black tie existence, treating the upper class with respect but not too much respect. They wouldn't attend a function, they joked to each other, unless there was at least one Duke present. A long lecture tour followed which also served as Hillary and his new wife Louise's honeymoon. Then it was back to their day jobs, Hillary to his bees, Lowe to his teaching. They reunited on other expeditions in Antarctica and the Himalayas.

The opening of the Hillary schools fostered alternative vocations for Sherpa children, helping many through their knowledge of English, to move faster through the ranks of trekking companies, many of which they now own. The Medical Superintendents at both Hillary Hospitals are Sherpa doctors, another, now a PhD in Forestry, is Warden of Mount Everest National Park. Another boy, who used to make aeroplanes from pieces of left over school building wood, now pilots jumbo jets in Europe. Another boy, who used to drive his teachers mad by drawing helicopters on every available surface, is now a helicopter pilot.

Next morning the flying Sherpa, Captain Dawa, arrives with his helicopter to transport Hillary and his party to Mount Everest School, its pupils mostly sons and daughters of Tibetan refugees. It's a long steep slope up to the school from the level ground where the helicopter has landed. A long hard climb. Once again the path is lined with beaming children offering Hillary flowers and silk scarves. But the atmosphere is muted. It is clear Hillary is suffering. He climbs slowly, his face is deathly pale and he is slurring his words. He is playing Russian roulette with his respiratory system.

Ever since Everest, Hillary has had problems with altitude. On a subsequent Himalayan peak he had a slight stroke and at the end of his Ocean to Sky Ganges Expedition he had a very lucky escape indeed. After abandoning the Ganges when the river became a waterfall, Hillary and his team set out to climb a peak as a symbolic end to the journey. Hillary was 59 but insisted on carrying as much as everyone else. Next morning at the highest camp he collapsed with cerebral oedema. There was no cure except rapid descent, and the team of old climbing friends hauled him down the mountain to an Indian Army post from where he was evacuated in a helicopter.

But here he is, 80-years-old, tempting fate once more. Today's summit is Mount Everest School, still a long slope away, and it's clear Hillary is putting more effort into this climb than he did on Everest in 1953.

Some days later Hillary travels by helicopter to spend some time in the villages closer to Everest, where his work began. The trekking trails to Everest pass through these villages and young western trekkers stare at this old man wondering what on earth he is doing here in young people's territory. Often I have watched Hillary sit quietly in tea shops while young trekkers, not recognising him, boast about their own trekking exploits.

I once filmed Hillary up here sitting on a rock, casually holding an ice axe, reminiscing with his son Peter. An American trekker chanced upon us, watched for a while, and unable to contain himself any longer, said to Hillary, "Hey, Bud, that's not the way to hold an ice axe," and proceeded to show him how to do it. Hillary thanked him but said nothing else. The American went off, still oblivious. Maybe the bee stings from his youth innoculated him from the Great Man syndrome. I know no man with less reason to be humble, yet know no man more humble.

In the village of Khunde Hillary enters his second home, the house of Ang Dooli, the wife of Hillary's dearest Sherpa friend, Mingma Tsering. Mingma was the foreman of all Hillary's early building projects. He could neither read nor write, but had a memory for detail that out-rivalled a computer. Mingma is dead now but his wife Ang Dooli, half Hillary's height, bustles about gathering ingredients for tea. This house was the Hillary family base in the happy days when Hillary, his wife Louise and their children were all here together working. Ang Dooli is the Hillary children's surrogate mother, their Sherpa mother.

In a corner of a room adorned with Hillary family photos, sits Ang Dooli's deaf mute son Temba. He is hard at work on his latest painting, a beautiful stylised landscape of the region complete with a yeti or two. Of Ang Dooli's eleven children, Temba was one of only three who survived childhood, a typical statistic which made Hillary realise early on how urgent it was to do something about the health needs of a region where iodine deficiency and other maladies were endemic. In 1965 he built the Khunde hospital which now treats 9,000 patients a year. In 1975, he built a 20 bed hospital in Paphlu and has built and staffed over a dozen village health clinics.

Downhill from Ang Dooli's house is Khumjung school. In 1983, Tenzing joined Hillary at the school to celebrate the 30th anniversary of their Everest climb. They sat together laughing uproariously as the children reenacted their famous climb on a rock in the school playground. That would be the last occasion Hillary and Tenzing would be together in the Himalayas. Three years later, in 1986, Tenzing died of pneumonia.

Tenzing, like many Sherpa second sons, had trained to become a monk but the life didn't suit him and he left for distant Darjeeling in the hope of getting portering work on the Everest Expeditions that used to pass through there. After climbing Everest, Tenzing continued to live in Darjeeling where India's Prime Minister Nehru had set up a lifetime position for him at the Indian Mountaineering Institute. With his modest salary, increasing family responsibilities and his physical distance from the people of Everest, Tenzing did feel saddened that he couldn't do more for his own people, and there developed some degree of unease between he and Hillary. But in Tenzing's declining years, which coincided with Hillary's years as New Zealand's High Commissioner to India, they saw a lot of each other and rekindled the deep friendship and respect they shared in 1953.

A few days later, back in Phaplu, the sun is setting. The day's work almost done Hillary is exhausted. George Lowe is reflective, and tries to put words to his thoughts. "There is no end to the need here. It is an uphill task. But that's Ed's strength, uphill tasks. I've seen it on Everest and I see it still. He'll just keep plugging on until he can't go one step more."

(Michael Dillon is one of the world's leading mountain cinematographers and documentary filmmakers. He took part in the First Australian Everest Expedition 1984.)