PLANE CRASH

As one of the older theories of the show's premise, dreams are subject to interpretation.

What does it mean if one dreams about a plane crash?

If you dream of a journey – airplane or car are the most common – that ends in a crash those crash dreams are about the fear of not hitting your goals. Perhaps they are unrealistic, or perhaps new circumstances have made them appear harder to achieve.

If you dream of a plane crash it suggests you are anxious about the failure of a project. The dream meaning is of you having planned a project that doesn’t get you where you thought it would – and is accompanied by the fear that things will end badly.

Plane crash dreams (and car crash dreams) are particularly common during recessions and times of financial crisis, and can be directly translated as someone worrying about their financial situation – a lifetime’s journey, with a planned end, where there is a sudden concern about getting safely to the goal.

However the dream can in fact relate to any important project or goal where there is a fear over successful completion.

Plane crash dreams can signify you have set unrealistic goals, that the goalposts have moved, or that events have suddenly obscured the finish line. The dream is an expression of your anxiety.

A dream of a plane crash represents your self doubt and your lack of faith that you can successfully complete a project.

Plane crash dreams can also represent an extreme fear of phobia of a future event.
Plane crash dreams are about your anxiety for the future. It is a mental life check.
It might therefore be an appropriate time to look at your goals to see if they are still achievable. Can you make changes so that your goals appear easier? Or do you need to recalibrate your goals to take into account current circumstances?

The fear of failure can often be overcome by a fresh analysis of the obstacles in your path and a more realistic plan on how to reach your goals.

Plane crash dreams represent project failure and the anxiety associated with meeting one's goals. Doubt, fear and failure are part of these dreams.

And it is clear that the main characters all had some sort of failure anxieties based on their back stories. Kate was anxious about escaping her crimes. Sawyer feared failure in not tracking down his parent's killer. Jack was worried about getting his father's acceptance. Hurley was distraught that he would never find love. Locke feared success in any endeavor, from school, career to relationships. They all worried about crashing and burning.

If LOST was a collective of the characters' plane crash dreams, how did they end? When one dreams about heaven, or their view of an after life existence, they dream  of  a place where there is no suffering and everyone is happy. So, if you dream about heaven, you could be seeking relief from the physical or emotional pain and sadness in your real life. 

In essence, the dream theory can explain the two disconnected features of the LOST universe: the island (dream of plane crash) and the sideways (dream of heaven) arcs.