Someone brought up using common sense and that is a very good point. Ocam's razor basically states that the simplest of competing theories should be considered first over the more complex ones.
This Poll on WS was done awhile back and there has been a lot more information obtained since the poll started but it is still very interesting to look at. Here are the current top 5 from the poll results:
1- hijacked + crashed into water (128 people voted)
2- landed safely on land (99 people voted)
3- hijacked + plane landed safely but is hidden (95 people voted)
4- i dont know (62 people voted)
5- pilot suicide + crashed into ocean (39 people voted)
All JMO
For #1, I began to think of common sense why this one may be it.
NOTE: IMO, #1 can include either the pilot, co-pilot, or some other hijacker because it is NOT specific as some people may not have noticed the other option or did not like the word suicide in the other option with #5. ANYBODY could become a hijacker including the pilot or copilot, so the wording of this poll is not clear enough IMO.
I am using just what news reports and info have been released of which we all know some of it may be rumors but going based on what I read somewhere in the past few weeks. Again, some of this may be rumor type info but listing it anyway.
For #1 (interpreted as ANY hijacker which could include anyone on board that plane, passenger, pilot, copilot, etc. It is not specific who hijacked plane):
-There was supposedly a purposeful turning off of communication transponders.
-There was supposedly a purposeful zig-zag pattern after turning left.
-The altitude of plane seemed purposeful going way up to over 40000 feet and then way down to around 5000 feet.
-If there was any type of mechanical failure, there was no identified attempt of an emergency landing anywhere which would have been a normal response to some severe mechanical failure. Instead, the plane took a heading south to the deepest most remote ocean.
-The plane flew for a very long time with no change of course to try to get near land or to try an emergency landing.
-There was rumored to be a call from the pilot to somone else on his cell phone before boarding.
-Another plane supposedly tried to contact this plane on emergency VHF frequency and he heard mumbled voices.
-The pilot was in court for his friend and his friend may be going to prison or jail after that court case.
-There were rumors of the pilot having an affair and rumors of trouble in his marriage.
-There were rumors of his wife leaving his normal house and flying to another location the day or 2 after this flight.
-There were 2 passengers with fake passports that were gotten from Ali. Nothing much more heard about these 2 people.
-There were rumors of the copilots phone being reconnected when the plane went low.
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JMO, in thinking about Occams Razor and who would have hijacked the plane, it seems plausable based on all the above that either the pilot or the co-pilot either worked together or 1 of them knocked out the other one to take over the plane. Then locked the cabin door so no passengers could get in OR used the 45000 feet height to knock them all out.
But the biggest thing that does not make sense is why go to remotest part of ocean and hide the plane deep in water. The best answer to this was what a few people have brought up. He may have wanted to try to make sure insurance money or his job's benefit money would still be paid out to his family and children. That is 1 good reason why he may have tried to hide the plane.
Because if it is found out the pilot or copilot did it on purpose, I am sure insurance and company benefits do NOT pay in those circumstances.
FINAL THOUGHT: Its plausable. This is just one of many possible reasons the plane ended up disappearing. For me personally, I am just keeping a list of all the possibles and have quit trying to pick just 1 reason and just wanted to bring this poll results to the forefront because it is interesting to think about what others have thought.