Germanwings: Shock and anger after 'deliberate' crash

In a chilling account of the final minutes of Germanwings Flight 4U 9525, lead prosecutor Brice Robin said Thursday that 28-year-old German Andreas Lubitz initiated the plane's descent into the French Alps while alone at the controls.

Lubitz appeared to "show a desire to want to destroy" the plane, Robin told reporters after his team analysed the Airbus A320's cockpit voice recorder.

The first officer, who was described by neighbours and fellow flying club members as a "friendly" guy-next-door type who enjoyed jogging with his girlfriend, was not however believed to be part of a terrorist plot, officials said.

German Chancellor Angela Merkel said the revelation added an "absolutely unimaginable dimension" to Tuesday's tragedy, in which 150 people were killed, mostly German and Spanish nationals.

It prompted airlines to review their cockpit policies, many announcing they will now require two crew members in the cockpit at all times.

Spain's Prime Minister Mariano Rajoy said he was "deeply shaken" by the news and sent his "heartfelt affection" to the victims' families, dozens of whom had arrived near the crash site.

They were briefed by the prosecutor, who said they reacted with "shock" to the findings.

Robin said the passengers were killed "instantly" by the crash and were probably unaware of the impending disaster until the "very last moment."

"The screams are heard only in the last instants before the impact," he said.

"The co-pilot was alone at the controls," he said. "(He) deliberately refused to open the door of the cockpit to the pilot."

The pilot, believed to have gone to the toilet, made increasingly furious attempts to re-enter the cockpit, banging on the door, the recordings appear to show.

Worst nightmares

In the northwestern German town of Haltern, which lost 16 students and two teachers killed while returning from a school exchange, the revelations caused shock and anger.

"Personally, I'm stunned, angry, speechless and deeply shocked," Haltern's mayor Bodo Klimpel told a news conference.

"I'm asking myself when this nightmare will end. It's bad enough for the families to learn of the death of loved ones in an accident. But when it's clear that an individual may possibly have deliberately caused the accident, it takes on an even worse dimension," Klimpel said.

The shaken principal of the stricken school, Ulrich Wessel, said "what makes all of us so angry (is) that a suicide can lead to the deaths of 149 other people ... It leaves us angry, perplexed, stunned."

The head of Germanwings' parent company Lufthansa, Carsten Spohr, said that "in our worst nightmares we could not have imagined that this kind of tragedy could happen to us".

A man in this 50s who gave his name only as Hans-Dieter travelled to the western German town of Montabaur to see Lubitz's home where he lived with his parents.

"I wanted to know where the murderer lived," he said.

Controls set to 'accelerate' descent

The French prosecutor downplayed the likelihood of Lubitz accidentally taking the plane down with an involuntary turn of the descent button.

"If you passed out and leaned over on it, it would only go a quarter-way and do nothing," Robin said, adding Lubitz, who had worked for Lufthansa since 2013, had set the controls to "accelerate the plane's descent."

For the eight minutes after he began the descent, Lubitz was apparently calm and silent, breathing normally and showing no sign of panic.