As investigators enter the fifth day of search for the missing Malaysian Airlines jet that disappeared from the radar screens over Southeast Asia with 239 people on board last Friday, the story has progressed from mysterious to confusing to downright frustrating. In the past, there have been many cases of planes experiencing malfunctions mid-flight and even some cases of those planes going missing for up to 2 years; this is an unfortunate reality of a flawed and somewhat dangerous system of transportation that millions of people use daily, without much fuss or fear. However, what sets this incident apart, and what has left many investigators, airplane engineers and technicians, pilots, and common readers baffled, is the compete lack of details and supported speculation regarding the plane’s cause of disappearance.

Here is what is known: The Boeing 777-200ER took off from Kuala Lumpur, Malaysia around noon on Friday (ET), scheduled to touch down in Beijing 6 hours later. About an hour into the flight, air traffic controllers in Kuala Lumpur completely lost contact with the plane while it was over the sea between Malaysia and Vietnam. There was no indication of any mechanical malfunctions, change in flight path, or distress of any kind reported by the pilots – communication and radar presence simply ceased. The chief of the Malaysian air force, General Rodzali Daud, stated that the radar suggested that the Boeing 777 changed direction from the direct route to Beijing, turning southwest, but then reversed this speculation 12 hours later, creating even greater confusion about where this plane may have ended up. On board, there were 239 people: 12 crew members and 227 passengers, two of which were Iranian men who had gotten onto the plane with stolen passports.

So far, all that has been reported about the potential causes of this strange disappearance only reach the status of speculation.  The potential causes that experts agree could cause such a rare mid-flight crash are mechanical, pilot error, or an act of terrorism. However, due to the excellent safety record of the Boeing 777, the lack of communication about any mechanical error, and the lack of connection to terrorist organizations of the two men with stolen passports or anyone on board, all of these causes remain unsupported. For now, dozens of ships and planes from various surrounding countries scour the South China Sea, searching for any debris or evidence of the missing plane and its passengers.