FRANKFURT, March 28  -- The crash of the Germanwings flight could be averted, but only in theory, not in reality, and this situation highlights the dilemma in which airlines can hardly find a solution, an expert has said.

The crash was the result of the flight plunging at a speed, which did not trigger a safety system of the plane, while no communications were made by the co-pilot, an expert told Xinhua recently on condition of anonymity.

According to him, the descent of the flight could also be attributed to some other reasons, such as the loss of pressure in the cockpit if there was a crack.

However, the flight was supposed to descend at a higher speed if there was a mechanical malfunction and the pilot lost control, he said adding that the flight envelope protection system on the A320 plane would have started to work and brought the plane to a safe condition in that case.

French prosecutor Brice Robin said at a press conference in Marseille on Thursday that the action of the first officer of the crashed Germanwings' A320 can be analyzed as his intention to destroy the aircraft.

If a pilot or co-pilot on a flight is determined to destroy an aircraft, can people on the ground do something to stop it?

"People on the ground are able to detect an abnormal condition of a flight and take control of it in technical theory. But it is not plausible in practice," he said.

He went on to explain that airlines have to spend money on data transmission between a flight and the ground controlling center. Unfortunately real time data transmission would be too expensive for airlines as well as average passengers, he commented.

In addition, remote control of a flight in the sky has been a controversial issue. Currently there is no problem for the technicians on the ground to take control of a flight but nearly no airlines are doing so, he said.

The expert clarified that there would be a serious threat if remote control is possible. What if a terrorist hacks into the controlling system? he asked.

Every time a disastrous accident occurs, airlines have to make some changes, he said. After the 9/11 attack, airlines were forced to fasten the door to the cockpit to prevent possible terrorists from gaining access to the cockpit and taking control of a flight.

However, it turned out that the co-pilot might have exploit the highly restricted entry of the door and deliberately crashed flight4U9525, which downed in the French Alps and killed 150 people on board en route from Spain's Barcelona to Germany's Duesseldorf.

It seems that airlines will have to tend to the psychological health of pilots, said the expert.