Lost

I watched the final two episodes of Lost - series two the other night.

The next day at work, people were going over what happened. The major event was the discovery that if "the button" wasn't pressed every 108 minutes, then a massive magnetic field would build up. One of the characters said that he caused the plane to crash because he didn't press "the button" in time.
The people at work said that the plane was therefore attracted to the island by the magnetic field.

HOLD ON A MINUTE.

What are planes made of ??? Aluminium.

Explanations on a postcard please .....