It's also possible that there were accomplices who didn't get paid what they were supposed to
VERY unlikely... those types would anonymously tip off cops of Cooper, as retribution. They would NOT keep it quiet....nobody does when getting stiffed.
If Cooper straight up stiffed an accomplice, I agree that the accomplice would probably tip off the FBI anonymously. Lots of people did tip off the authorities anonymously, though. It could be that the tip was not considered reliable. Also, in a scenario where Cooper didn't end up with the money either (e.g. Cooper dies, or the bag doesn't stay tied to him), I would think that accomplices would want to avoid the risk of even an "anonymous" call (assuming that they believed that he died, or that the bag came loose).
I didn't really have an opinion on whether any of the stewardesses were in on it until I read your post below. I hadn't really thought about the fact that there isn't really anything that a stewardess would be able to do for Cooper other than what she would normally do in a hijacking. That's a good point.
You guys are dancing around this but haven't put all the pieces together..
For almost 50 years people have been trying keys in the lock but it doesn't open..
This unlocks the door. We just have to open it.
It doesn't involve any specific suspect or prior contact (collusion).
Way to dodge the question Flyjack... 
don't make me go to the dark side here 
... but THAT was a bullshit answer... if you wanna push your suspect, then it is subject to scrutiny, and if you are implying Mucklow was in on it, then spell it out exactly, instead of these riddles.
How can you call it BS when you don't know what it is, this is why I hold back info, dealing with out of context comments and personal attacks like that.
Hahneman is my #1 suspect, no secret but this has ZERO to do with him specifically. It applies to any suspect, known or unknown. NO prior contact, NO collusion, NO love affair nonsense, get it. It is all there for anyone to figure out.
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