The first photo of a German pilot who was hailed a hero for attempting to prevent his co-pilot from flying a passenger airliner into a mountainside in the French Alps has emerged.

Capt Patrick Sondheimer, 36, was among the 150 victims of the Germanwings Flight 4U9525 crash of 24 March.

His features remained widely unknown to the public until a framed picture of him was displayed at a memorial for those killed in Cologne, Germany.

However, in a move that raised some eyebrows, the image was placed next to the portrait of the co-pilot of the Barcelona-Dusseldorf flight, Andreas Lubitz, who allegedly deliberately killed all those on-board.

According to black box recordings, Lubitz, 27, encouraged Sondheimer to take a toilet break after the Airbus A320 reached cruise altitude, leaving him alone in control of the flight.

He then locked the pilot out of the cockpit and initiated the plane's final eight-minute descent into the Alps.

Sondheimer, a father of two, could be heard on black box voice recorder, as he frantically attempted to re-gain access to the cockpit, initially shouting to his colleague to "Open the damn door" and then taking a fire-safety axe to it, but to no avail.

A private person with no obvious social media presence, Sondheimer was an experienced captain with more than 6,000 flying hours on the clock.

He had recently asked Germanwings' parent company Lufthansa to switch him from long-haul to short-haul flights so he could spend more time with his wife, six-year-old daughter and three-year-old son.

"My grandson is dead and all because of an idiot who did this to his whole flight and killed so many people," Sondheimer's grandmother, Marianne, told the Daily Mirror.