(Bloomberg) -- The co-pilot of the Germanwings flight that crashed in the French Alps appears to have deliberately flown the aircraft into a mountain side after locking the captain out of the cockpit, French prosecutors said.

Audio files from the last minutes in the cockpit of the Barcelona-Dusseldorf flight show the co-pilot took the aircraft into a descent after the captain left the flight deck and was denied re-entry, prosecutor Brice Robin said at a press conference in Marseille. The co-pilot could be heard breathing and remained otherwise silent right until the plane slammed into a mountain slope at full speed, he said.

The findings point to a deliberate destruction of the Airbus A320 single-aisle aircraft that killed 150 people rather than a technical fault, in what is the worst aviation accident yet for Deutsche Lufthansa AG and its Germanwings low-cost unit. The co-pilot was named by Robin as Andreas Lubitz, a 28 year-old German citizen, and Lufthansa said he had been deemed in tests completely fit to fly.

The crash on Tuesday has mystified investigators because the plane had flown in normal daylight conditions and had undergone routine checks. The second flight recorder, which stores data parameters from the plane’s performance, has not yet been recovered from the field of debris, Robin said.

David Fuller's view

You probably know all about this tragic event and I post the report only because of the uncomfortable coincidence with nervous, choppy markets, not least on Wall Street.  Gut level instincts such as fight or flight are an ever present aspect of markets, contributing to their far greater short-term volatility than underlying economic conditions would suggest. 

Crash talk has been a feature throughout this bull market to date, often reassuring for contrarian thinkers, and it has increased in recent months.  Mental images of airplanes mysteriously falling out of the sky are alarming analogies for investors otherwise enjoying the market ride.

We all hope to avoid complacency in markets which do occasionally plummet.  However, I maintain that the risk of a serious stock market crash such as 2008 is low, not least because of very accommodative monetary policies.  Nevertheless, there are plenty of uncertainties and these can easily contribute to volatility.