Crash investigators are rushing to find the onboard data recorder from Germanwings Flight 9525 to confirm prosecutors’ suspicions that the co-pilot steered the jet into a mountain after locking the captain out of the cockpit.
Audio files from the flight deck revealed that the co-pilot began descending after the captain stepped into the cabin, then denied him re-entry, prosecutor Brice Robin said in Marseille, France. Except for his breathing, the co-pilot stayed silent until the plane slammed into a slope at full speed, Robin said.
The findings from the voice recorder on the Airbus A320 suggest that the crash, the worst-ever accident for Deutsche Lufthansa AG and its Germanwings unit, was deliberate rather than due to a technical fault. The data unit, the second half of the airliner’s so-called black boxes, is important because it tracks the changes made by the crew to the controls.
“The most plausible interpretation is that the co-pilot voluntarily refused to open the door for the captain and activated the button controlling the plane’s altitude for a reason we don’t know,” Robin said Thursday at a press briefing. The action “can be interpreted as a desire to destroy the plane.”
Robin identified the co-pilot as Andreas Lubitz, a 28-year-old German citizen who Lufthansa said been deemed completely fit to fly following tests. Flight 9525 was en route to Dusseldorf, Germany, from Barcelona, Spain, with 150 people on board when the crash occurred on Tuesday.
The voice and data recorders are housed in specially reinforced cases to protect against the forces of a crash and painted orange to ensure visibility amid the wreckage. The single-aisle A320 from Airbus Group NV was largely pulverized by the impact, which Robin estimated occurred at 700 kilometers (435 miles) per hour.
Data gathered by tracking service Flightradar24 showed Flight 9525’s autopilot initially was programmed to 30,000 feet (9,100 meters) as the jet climbed, then reset to 32,000 feet and finally to its 38,000-foot cruising altitude, co-founder Mikael Robertsson said. Then the autopilot was manually reset to 96 feet, he said.
“After four minutes we see someone playing with the autopilot and changed it to the lowest setting,” Robertsson said in an interview.
That amounted to a death sentence for a plane crossing rugged terrain with an elevation of a mile above sea level. Robertsson said Flightradar24 turned over the information to investigators.
The crash had mystified authorities because the plane was flying in normal daylight conditions and had undergone all required maintenance checks.
Richard Healing, a former member of the U.S. National Transportation Safety Board, said the events disclosed by French prosecutors still leave some room for alternative interpretations.
“You can’t rule out the possibility at this point of the pilot who was remaining in the cockpit becoming incapacitated simultaneous with when the other pilot walked out,” said Healing, who now runs R Cubed Consulting LLC in Washington. “It’s more likely that the pilot may have done something intentionally, but you can’t conclude that until the flight data recorder is recovered.”
Lubitz, the co-pilot, had passed all medical tests and checks, and had started training in 2008, both in Bremen in northern Germany and in Phoenix, before joining the airline in late 2013, Lufthansa Chief Executive Officer Carsten Spohr said.
Cockpit personnel undergo thorough examination, said Spohr, calling the incident a “tragic, isolated case.”
The co-pilot had interrupted his pilot training for several months, though Spohr said he couldn’t give a reason. Pilots undergo medical tests once a year, and a psychological examination occurs at the start of their careers, Spohr said.
Germanwings said it cannot comment further because the investigation is a matter for the authorities. France’s BEA air-accident investigator is leading the probe into the tragedy.
Lufthansa, which operated the A320 before it was handed to Germanwings in early 2014, said the cockpit had a fortified door with video surveillance to prevent unauthorized entry, a measure that became mandatory after the 9/11 terror attacks. While pilots have a security code that lets them open the door from the outside, the person in the cockpit can still deny access.
Some airlines require two people on the flight-deck when one pilot steps out, making it necessary for cabin crew to stand in, and U.S. carriers all must do so under Federal Aviation Administration rules. Norwegian Air Shuttle ASA and Air Canada were among airlines saying they were adopting that rule or planning to do so.
Based on an official video from Toulouse, France-based Airbus, a pilot exiting the flight deck of an A320 can be prevented from re-entering if the remaining aviator operates manual locks on the inside of the cockpit door.
Flight-deck doors were turned into impenetrable barriers in the wake of the Sept. 11 terrorist attacks. While the measures have greatly improved protection from potential hijackers, the Airbus video shows that they’ve made it equally difficult for crew to access the cockpit in the event of an emergency or aberrant action by a sole pilot.
Germanwings said the captain of Flight 9525 was “very experienced” and had flown for charter carrier Condor and Lufthansa’s main brand for about 10 years before joining the parent company’s budget unit in May 2014. He had logged more than 6,000 flight hours.
Both pilots were trained “to Lufthansa standards,” according to Germanwings, which declined to release their personal details.
Lubitz came from Montabaur, about an hour north of Frankfurt, according to the local mayor’s office, and had been part of the local aviation club, which said on its website that it was “horrified” to learn that a member was among the dead.