Cannot seem to eject or get out of any chopper specifically if switched to copilot, and having taken over controls, and the engine is destroyed. when you land you have no option to get out until you release the controls. as of 0.72, subordinate AI pilot cannot get-out either until you release controls.
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EDIT- as of DEV 1.05.111302 (10/17/2013) - AI ignoring disembark commands (while copilot haven taken controls) appears to be somewhat unrelated; AI will not disembark whether or not the engine is damaged, until controls are released by player copilot.