Icelandic volcano ash cancels 500 flights

Passengers sleep on the floor in the main terminal at Edinburgh Airport, in Scotland May 24, 2011. Ash from an Icelandic volcano forced the cancellation of dozens of flights to and from Scotland on Tuesday but Ireland's Ryanair said it would protest against "unnecessary" restrictions.  [Photo/Agencies]

Passengers sleep on the floor in the main terminal at Edinburgh Airport, in Scotland May 24, 2011. [Photo/Agencies]