By Marc Herwig

Le Vernet (France) - Ten years ago, a Germanwings plane crashed on its way to Düsseldorf. 150 people died. Many people are particularly moved by the fate of a group of schoolchildren - and the cause of the crash.

Principal Ulrich Wessel will never forget the moment when he had to tell the parents the terrible news.

In a classroom at the grammar school in Haltern am See on the northern edge of the Ruhr region sit the mothers and fathers of the children who were on their way back from a student exchange in Spain. Booked on flight 4U9525 from Barcelona to Düsseldorf.

On the news, images of a plane crashing in the French Alps have long been running in an endless loop. And then the passenger list brings certainty: the 16 pupils and their two teachers were on board. No one survived.

When Wessel comes into the classroom with this information to the parents, worlds collapse. It was ten years ago now. "The horror was unimaginable," recalls Wessel.

The crash of the Germanwings plane at 10.41 a.m. on March 24, 2015 is one of the biggest disasters in European aviation history. Of course because of the many victims - 150 people - but also because of the cause of the crash.

Investigators in France and Germany still have no doubt that the 27-year-old co-pilot Andreas Lubitz deliberately steered the plane into the rocky massif near Le Vernet because he wanted to end his life - with 149 innocent people on board.

At their monthly meetings today, the parents of the Spanish exchange group from Haltern share fond memories, talk about their children and sometimes even cry together.

"It's now the tenth year, and the pain is still just as deep . You wake up with it and you go to bed with it," says Engelbert Tegethoff. His daughter Stefanie was 33 and one of the two teachers who accompanied the group of students to Spain.

She had got engaged a few months before the disaster, was planning a future with her partner, wanted to move in with him and start a family. What would her life be like today? And that of the pupils? "Losing your own child is unimaginable," says Tegethoff.

The tenth anniversary of the crash is a particularly poignant moment for many relatives. Many will accept Lufthansa's invitation to travel to Le Vernet, the site of the crash in the French Alps.

In Haltern, the pupils and teachers of the Joseph-König-Gymnasium will gather at the memorial plaque on the anniversary and lay down white roses.