The casting is credible (even Michelle Dockery manages to shake off her dour Downton garb) and the story is (just about) plausible. Thankfully the trailer did not reveal all. It is a bit a corny ('flawed man finds himself in a crisis') but transposed into a modern day and dangerous setting that we can all relate to, it becomes fresh again.
SPOILER ALERT: Do not read any further as I am about to reveal something of the plot line.
At a key point in the film, Liam Neeson's character has to regain control and the respect of the passengers (things are rather getting out of hand). How does he do that? He does not use violence and he does not use threats. Instead, he is disarmingly honest about his failings. In one leap, he transcends the two dimensional and 'not to be trusted' air marshal into being a three dimensional human being that is to be trusted and followed.
This is true of many leaders who have to handle people's reactions based upon what those people think they know about the leader rather than what the leader actually is. Poor leaders continue to wrestle with the impressions people have of them. Good leaders will reveal themselves in three dimensions to those whom they seek to lead.
How much of 'you' do you reveal?