Philippa Connolly's grandfather died in a mysterious air crash 35 years ago. She explains why she still wants to find out what happened.

At 9.33 a.m. on September 11th, 1968, an Air France Caravelle SE-210 plunged into the Mediterranean Sea off the coast of Nice, killing all 95 passengers and crew. Two days later a mother and four daughters from Sydney Parade Avenue in Dublin received the news that their husband and father had been on board. Their address had confused the French authorities, who had spent time trying to find the next of kin of Arthur O'Connor in Sydney, Australia.

He was one of two foreign passengers on the flight from Ajaccio, in Corsica, to Nice. All of the others were French, mainly from Corsica. The Irishman, aged 52, was my grandfather. He had been on holiday in Nice and decided to visit Corsica. At the time of the crash he was returning to Nice.

I was born many years after his death but grew up with the knowledge of the event ingrained in the family history. I knew him from photographs but never knew enough about him to really feel a connection. So I jumped at the chance to attend a ceremony in Nice last month to mark the 35th anniversary of the crash. I wanted to find out as much as I could about the circumstances of his death, but I went with a degree of trepidation, not knowing what I might discover.

On my way I read about the series of events leading up to the crash. At 9.29 a.m. the pilot declared that all was well. Ninety seconds later the control tower received a distress call from the plane: "We have some problems: we request an emergency landing at Nice. We have a fire on board." This was shortly followed by the final communication: "There's nothing we can do. We're going to crash if this continues."

The passengers had been prepared for an emergency landing. Only three minutes from landing and 268 seconds after the first announcement, the Caravelle was resting on the floor of the Mediterranean. Only three bodies were found; the cause of the crash was undetermined.

When I arrived at Église Sainte Hélène in the city for the hour-long service I didn't know what to expect from the commemoration. I was unsure whether there would be floods of tears and uncontrollable wails, stony faces or questioning ones. As I entered the church, however, my question was answered - it was different for everyone.

There were ladies in deep mourning, dressed in black mantillas; there were people crying; there were people smiling; and there were people who seemed indifferent. Despite everyone reacting differently, it was clear they all felt the same, in that nobody knew exactly what had happened to their loved one but all wanted to find out.

At the ceremony I met Louis Paoli, who was 20 when he lost his parents in the crash. Since then he has dedicated his life to finding out what happened to the Caravelle. As we sat down together the first thing he said was: "I'll search for the truth until the end of my days. It's the only goal of my life." He has spent 35 years contacting families, talking to officials, bombarding the French government and military with questions and letters and meetings. He has become the official spokesman for the families of the victims.

He believes the kind of damage the aircraft sustained, the state of the remains that were found and witness reports all point to a missile. At the time of the flight many military aircraft were in the sky surrounding the Caravelle, and several naval ships were below. They were carrying out a military demonstration with missiles that search for a heat source to attach to. The left engine of the plane would have provided such a source.

A journalist working on a military base in Antibes that morning had taken a photograph of the Caravelle nose-diving into a sea swarming with naval ships. The photograph subsequently went missing, as did several of the witness reports. In a government system as organised as France's, one might wonder how vital documents get misplaced. Those that have not been misplaced, however, and relate to the crash, will not be released by the military until 2018 - 50 years after the tragedy.

After the crash it was several months before the first attempts were made to bring up the remains from the ocean floor. Only eight tonnes of debris were dredged up. Strangely, the French authorities claimed the end of the black-box tape was damaged, so nothing could be proved.

When asked what truth he was searching for and when he would be satisfied, Paoli replied: "I want them to simply admit that it was them. I want them to take their rightful responsibility."

The commemoration was very impressive, but it was meeting people such as Paoli that was most valuable. Even though I had never met them before, I was their friend. Not because they knew we were going to get along, but because it didn't matter.

We had been automatically connected by my grandfather and their sister or my grandfather and their son. For I was another generation that was going to continue talking about it, that wasn't going to forget, that was going to join them in discovering the truth.