Victims' families 'having a hard time believing it'.

• Author: Charlton, Angela
• Position: News

Byline: Angela Charlton and David McHugh

PARIS -- Passengers with moments to live screamed in terror and the pilot frantically pounded on the locked cockpit door as a 27-year-old German co-pilot deliberately and wordlessly smashed an Airbus carrying 150 people into an Alpine mountainside.

The account Thursday of the final moments of Germanwings Flight 9525 prompted some airlines to immediately impose stricter cockpit rules -- and raised haunting questions about the motive of the co-pilot, whose breathing never wavered as he destroyed the plane and the lives of those aboard.

''We have no idea of the reason,'' Marseille Prosecutor Brice Robin said, revealing the chilling conclusions investigators reached after reconstructing the final minutes of the flight from the plane's black box voice recorder. Co-pilot Andreas Lubitz's intention was ''to destroy this plane.''

French, German and U.S. officials said there was no indication of terrorism. The prosecutor did not elaborate on why investigators do not suspect a political motive; instead they're focusing on the co-pilot's ''personal, family and professional environment'' to try to determine why he did it.

German Chancellor Angela Merkel, whose nation lost 75 people on the flight, said the conclusions brought the tragedy to a ''new, simply incomprehensible dimension.'' Devastated families of victims visited the crash scene Thursday, looking across a windy mountain meadow toward where their loved ones died.

The Airbus A320 was flying from Barcelona to Duesseldorf on Tuesday when it lost radio contact with air traffic controllers and began plunging from its cruising altitude of 38,000 feet, before slamming into the mountainside eight minutes later.

The prosecutor laid out in horrifying detail the final sounds heard in the cockpit extracted from the mangled voice recorder.

Lubitz, courteous in the first part of the trip, became ''curt'' when the captain began the mid-flight briefing on the planned landing, Robin said.

The pilot, who has not been identified, left the cockpit for an apparent bathroom break, and Lubitz took control of the jet.

He suddenly started a manual descent, and the pilot started knocking on the door.

There was no response. ''It was absolute silence in the cockpit,'' the prosecutor said -- except for the steady breathing he said indicated Lubitz was not panicked, and acted in a calm, deliberate manner.

The A320 is designed with safeguards to allow emergency entry into the cockpit...