germanwings plane crash
Debris from an Airbus A320 is seen in the mountains, near Seyne-les-Alpes, March 24, 2015 in this still image taken from TV.Reuters

With reports emerging that one of the two pilots on the doomed Germanwings 4U9525 flight that crashed in the French Alps on Tuesday had been locked out of the cockpit, the mystery around the plane's crash in otherwise normal conditions took a new turn, with conspiracy theories going wild online. 

The cockpit voice recorder of the Germanwings Airbus A320 has revealed that one pilot (it is not clear if it was the captain or the first officer) left his seat to step outside the cockpit. He knocked on the door to re-enter, but the second pilot never opened the door. 

This revelation has sparked theories of what could have transpired inside the cockpit when one pilot was in charge. Netizens poured out their thoughts on this development on Twitter, posting about several possibilities:

Pilot deliberately Crashed the Plane? Revenge or Suicide?

One of the raging theories is that the pilot who remained in the cockpit intentionally locked the other pilot out and deliberately crashed the plane.

This theory seems to have precedence in the 1999 EgyptAir Flight 990 crash in New England which was said to be an 'act of revenge'.

The pilot had been warned for sexual misconduct, and reports claimed that he shut down the plane's engines as an act of revenge, according to The Guardian

In the case of the Germanwings Airbus A320, it is still not clear why the second pilot who was inside the cockpit did not open the door, despite the other pilot attempting to 'smash it down'. 

"You can hear he is trying to smash the door down," an investigator told The New York Times

"We don't know yet the reason why one of the guys went out. But what is sure is that at the very end of the flight, the other pilot is alone and does not open the door."

Here's what Twitterati said, with some even speculating if it was a case of 'pilot suicide'.

Terror Attack or Hijack?

While French authorities, and even the White House, had said earlier that terrorism was the least likely cause of the crash, the new development opens doors to the possibility that the crash may have been a planned incident. 

The Germanwings 4U9525 flight was said to be flying in perfectly normal weather conditions and there was no distress call from the cockpit even as the plane descended for nearly eight minutes. 

Air traffic controllers attempted to make contact with the flight when it began its descent, but received no response. 

Did the Pilot Face Medical Emergency?

One theory that is running on a lot of minds going by Twitter posts is whether the pilot who remained in the cockpit suffered a heart attack or other medical emergency, which left him incapable of controlling the plane or even opening the cockpit door to let the other pilot inside. 

What lends more credence to this theory is that two pilots flying a Germanwings flight five years ago had nearly passed out during landing, due to what was suspected to be contaminated air, according to Daily Mail