The plane went completely off track, the world is big and a lot of the pieces sank. They couldn't have prepared for that. All the stuff like that radar going off can be explained if the Pilot was behind it.
What would they get out of lying? If it's missing and flying through another dimension than it's not something that should be covered up. If it was hijacked, or whatever else, I see no reason to hide it.
omg! the possibility of it being shot down is actually pretty real! although i do believe in aliens too I dont know...I feel like aliens would attack mostly during the night time to make sure they wernt blowing off their cover or something. the flight was during the daytime right?
They could have abducted the whole plane who knows ...