Personnel at six UK airports owned by BAA have voted to strike over a pay dispute. The airports are Heathrow, Stansted, Southampton, Glasgow, Edinburgh, and Aberdeen.
Here is the BBC report.
The union will soon announce dates targeted for a strike. They won't just go out for days or weeks on end. Instead, they will announce specific dates on which they will strike.)
In case of a strim\ke, there's a good chance Heathrow would close.