The plane started lurching and bumping in the air. Then, in a single, catastrophic moment, a bolt of lightning hit one of the fuel tanks and tore the right wing off. Lansa Flight 508 went into a nosedive and all 92 of its passengers and crew were killed, except for one.

One minute Juliane Koepcke, 17, was sitting in the window seat next to her mother; the next she was falling through the air, still strapped to her seat, and her mother had vanished. The filmmaker Werner Herzog, who some 30 years later was to make a documentary about Koepcke’s extraordinary survival, said, ‘She did not leave the airplane, the airplane left her.’

Koepcke has often wondered why she didn’t drop like a stone through the sky like the others. In the jungle after the crash she found the remains of a bank of three seats, like the one she and her mother were sitting in, although this one was rammed head first about three feet into the soil. ‘The heads of the passengers – two men and a woman – were stuck there in the rainforest floor.’

She has four theories about how she survived the fall: first, that the powerful updraught from the thunderstorm slowed her plunge; secondly, that the three-seat bench worked like the wing of a maple seed spinning as it fell (this is Herzog’s explanation); thirdly, that the trees where she fell were particularly dense and knitted together; and lastly, that she hit the trees with the seat below her, and fell through the branches ‘as in a boat’ to land relatively gently on the rainforest floor.

I shouted out for my mother but I only heard the sounds of the jungle. I was completely alone.

I had broken my collarbone and had some deep cuts on my legs but my injuries weren’t serious. I realised later that I had ruptured a ligament in my knee but I could walk.

Before the crash, I had spent a year and a half with my parents on their research station only 30 miles away. I learned a lot about life in the rainforest, that it wasn’t too dangerous. It’s not the green hell that the world always thinks.

I could hear the planes overhead searching for the wreck but it was a very dense forest and I couldn’t see them.

I was wearing a very short, sleeveless mini-dress and white sandals. I had lost one shoe but I kept the other because I am very short-sighted and had lost my glasses, so I used that shoe to test the ground ahead of me as I walked.

Snakes are camouflaged there and they look like dry leaves. I was lucky I didn’t meet them or maybe just that I didn’t see them.

At the crash site I had found a bag of sweets. When I had finished them I had nothing more to eat and I was very afraid of starving.

It was very hot and very wet and it rained several times a day. But it was cold in the night and to be alone in that mini-dress was very difficult.

On the fourth day, I heard the noise of a landing king vulture which I recognised from my time at my parents’ reserve.

I was afraid because I knew they only land when there is a lot of carrion and I knew it was bodies from the crash.

When I turned a corner in the creek, I found a bench with three passengers rammed head first into the earth.

I thought my mother could be one of them but when I touched the corpse with a stick, I saw that the woman’s toenails were painted – my mother never polished her nails.

I was immediately relieved but then felt ashamed of that thought.

By the 10th day I couldn’t stand properly and I drifted along the edge of a larger river I had found. I felt so lonely, like I was in a parallel universe far away from any human being.

I thought I was hallucinating when I saw a really large boat. When I went to touch it and realised it was real, it was like an adrenaline shot.

But [then I saw] there was a small path into the jungle where I found a hut with a palm leaf roof, an outboard motor and a litre of gasoline.

I had a wound on my upper right arm. It was infested with maggots about one centimetre long. I remembered our dog had the same infection and my father had put kerosene in it, so I sucked the gasoline out and put it into the wound.

The pain was intense as the maggots tried to get further into the wound. I pulled out about 30 maggots and was very proud of myself. I decided to spend the night there.

The next day I heard the voices of several men outside. It was like hearing the voices of angels.

When they saw me, they were alarmed and stopped talking. They thought I was a kind of water goddess – a figure from local legend who is a hybrid of a water dolphin and a blonde, white-skinned woman.

But I introduced myself in Spanish and explained what had happened. They treated my wounds and gave me something to eat and the next day took me back to civilisation.

The day after my rescue, I saw my father. He could barely talk and in the first moment we just held each other.

For the next few days, he frantically searched for news of my mother. On 12 January they found her body.

Later I found out that she also survived the crash but was badly injured and she couldn’t move. She died several days later. I dread to think what her last days were like.