Germanwings airplanes are shown at an airport in Dusseldorf, Germany, on March 27, 2015. The crash of Flight 9525 has reignited debate over whether passengers may be safer on pilotless planes. Reuters

The claim by French investigators that the co-pilot of Germanwings Flight 9525 intentionally crashed the aircraft into the French Alps on Tuesday has spurred debate that planes might be safer without pilots. But getting passengers, insurance companies and pilot unions on board for that idea remains a challenge.

In the case of Flight 9525, co-pilot Andreas Lubitz reportedly prevented the pilot from reentering the cockpit after the pilot briefly left, and then Lubitz sent the plane into a controlled descent that led to the crash. The disaster has already sparked a recommendation among the regulator of European airlines: Two pilots should be required to always be in the cockpit -- the same rule that has been in place in the United States since the Sept. 11 terrorist attacks, the Associated Press reported Friday.

If planes were fully automated and could be controlled from the ground when aircrafts encounter an issue, then the tragedy of Flight 9525 -- which took off from Barcelona, Spain, and was bound for Dusseldorf, Germany, before crashing in the Alps -- could have been averted, the advocates of no-pilot planes claim. But critics say self-flying aircraft have their own problems, including unreliability, vulnerability to hacking, jittery potential customers and an unwillingness on the part of insurers to cover such planes. Then there are the unions, which are concerned that self-flying planes would leave pilots out of jobs.

“There has always been a desire to have the ability to control planes from the ground. … But the ground element of that was entirely pooh-poohed by the aviation industry for a whole variety of reasons, not least of which is aircraft safety,” aviation safety analyst Chris Yates told the Daily Mail. “Questions will always be posed as to whether pilots should be taken out of the equation in the event of something like [Flight 9525] so ground control would take over. … I personally would not feel comfortable getting on any airliner where control could be taken away from the pilots and co-pilots.”

Fully automated flights are already in existence, at least in military usage. Drones have been conducting missions in Iraq, Afghanistan and other areas for years. But their safety record is nowhere near that of commercial aviation: Up to 1 in 3 drones crashes, Bob Mann of the airline industry and consulting firm R.W. Mann & Co. told Business Insider.

Boeing developed a system to have planes controlled from the ground to prevent a hijacking in progress, but airlines questioned its safety. The program hasn't been widely adopted and the technology is unproven, the Daily Mail reported.

Mann said the barrier to fully automated flights getting off the ground isn’t just from the airline industry, but from companies reluctant to insure planes that fly without pilots. “It would take a sea change on behalf of the insurance industry,” he pointed out, noting that insurers haven’t yet decided to cover planes with fewer than two pilots, let alone none.

Some are concerned that the calls for pilotless aircraft are a knee-jerk reaction to the Germanwings crash. A spokesman for the British Airline Pilots Association (BALPA) told the Daily Mail that the industry “must act with careful consideration to ensure we don’t create new safety risks or concerns such as those raised by the vulnerability of any form of remote control of a passenger aircraft.”