( CNN ) There were screams . Then the sounds of a commercial jetliner slamming into the mountainside . And finally silence . Deathly silence . That much is known about the final few minutes for the 144 passengers on Germanwings Flight 9525 . Beyond that , it 's a matter of imagination and speculation -- about what they saw and what they felt as their plane approached and then crashed into the Alps . None of them can speak for themselves , nor can any of the flight 's six crew members . But authorities have given some clues , based on what investigators know about the aircraft 's trajectory and what they 've heard on a mangled cockpit voice recorder recovered at the crash site . It all began on what seemed like most any other Tuesday as citizens of 18 countries packed into the Germanwings plane in Barcelona , Spain . The passengers came from all walks of life , using Lufthansa 's low-cost carrier to get to Dusseldorf , Germany . They were high school students , heading home after a week in Spain . They were parents and children enjoying their vacation . There were businessmen , scouting out store locations . There was a 26-minute delay before takeoff because air traffic controllers did n't give the OK to start the plane 's engines earlier and there was a small wait in the takeoff rotation , according to Lufthansa . For any frequent flier , that kind of delay is nothing abnormal . Nor , it seems , was takeoff . The Airbus A320 left and headed northeast at 10:01 a.m. ( 5:01 a.m . ET ) on what should have been a 726-mile journey . The plane leveled off at 38,000 feet , its cruising altitude . By this point , passengers would be OK to unbuckle , head to the restroom or get their bags out of the overhead bin . A seemingly innocuous act changed everything : The aircraft 's pilot had to use the restroom , according to Lufthansa CEO Carsten Spohr , telling the co-pilot that he was stepping out . It 's possible that passengers saw the captain in the cabin , going to or from the restroom . They also could have noticed that the aircraft was going down -- even though they were about a half-hour into a nearly two-hour flight , with the Alps ahead of them . The passengers could n't have known it , but the co-pilot -- identified as 28-year-old Andreas Lubitz -- '' manipulated the buttons of the flight monitoring system to activate the descent of the aircraft '' while the pilot was out , Marseille prosecutor Brice Robin said Thursday . This was around 10:45 a.m . It was n't like the plane suddenly jerked down , plunging straight into the ground . Authorities described a steady descent at a rate of about 3,000 to 3,500 feet ( or roughly 1,000 meters ) per minute . Still , it is the kind of descent you 'd expect while nearing an airport -- not traversing the Alps . If passengers did n't notice that fall , they might have caught wind of what was happening at the front of the plane . Students , singers among the victims . Inside the cockpit , the only sound was that of Lubitz breathing steadily . But outside the cockpit , the noises apparently grew louder and more frantic . The pilot tried to open the door but could n't get in . He likely knocked on the door . He used a video conference system to talk to the co-pilot , Robin said . None of it worked . Nor did his last-ditch attempt , as recounted by a senior French military official involved in the crash investigation to The New York Times . `` You can hear he is trying to smash the door down , '' the official said . Did the passengers hear this commotion upfront ? It 's hard to imagine they did n't . And if that was n't reason enough to cause worry , they just had to look outside -- at the mountain chain that should have been far below them instead of getting closer and closer and closer . The voice recorder did n't indicate any abnormal noise in the cabin until the final few moments . Still , even if the passengers did n't know it at the time , all it took was eight minutes for a seemingly normal flight to become a nightmare . The nightmare ended in a violent crash into rugged , remote terrain . So did the screams and the lives of all 150 people on Flight 9525 -- a death that Robin described as `` instantaneous . '' Who was co-pilot Andreas Lubitz ?
Germanwings Flight 9525 had a slight delay before taking off from Barcelona , Spain . After leveling off at 38,000 feet , the plane descended steadily before reaching the runway . Voices were heard in carpenter 's cabin in minutes before crash , according to audio recording .