Can commercial airplanes be converted to drones?
Is it possible to convert a Commercial Airplane into a Drone


For what its worth, yes this would be technically possible however it comes with some risks. 

When To Take Control: This brings into the simple idea that in an emergency the pilot may need to be in control of the situation as they often have the most information about exactly what is happening. If the plane had a serious issue and the ground controller did not know what was happening they may take control and only exacerbate the problem.  

Connection Reliability: Keep in mind that planes are flying at very high altitudes moving quite fast. Maintaining a reliable connection in these conditions is difficult. Since a reliable connection is hard enough to maintain you again may create more issues than you solve. This also has to be a fully duplexed channel since the plane needs to transmit its telemetry and receive control inputs in what is more or less real time. At this point the data up/down rates would push the limits of what we can do today.     

Connection Security: As mentioned you would need to secure the connection to prevent someone from taking it over maliciously. This in and of its self is a big problem. But lets not turn this into a digital security debate.  

Cost: As nice as safety is its not free. Since there is currently no system in place on a global scale to do this it would have to be created. Someone has to pay for that and unless the FAA is going to require it you will have to get the airlines/aircraft makers on board with this voluntarily. On top of that any system that is added like this would have to be certified by the FAA. 

So while it is possible there are very real barriers to a system like this include but are not limited to the ones listed above and before someone comes back with the "if it makes it safer than we should spend the time figuring it out" response I will mention that modern technology is as good as it is and there are already companies and individuals researching new tech like this but Keep in mind that with FAA regulations taking the time they do to get, planes are flying with tech that is now considered "dated" by the tech world.