Whilst agreeing with comments about there being no need to deflate tyres in theory, my advise is to do so, following my experience when flying from Bournemouth to Pisa. The check-in staff accepted my bike in a CTC plastic bag with tyres fully inflated. Upon collection at Pisa I found very neat puncture slits (screwdriver or pen knife sized) in each tyre side wall. I assume that some kind baggage handler at Bournemouth Airport isn't a keen cyclist !!!!
I hold baggage handlers in as much esteem as politicians, bankers, estate agents and Mr. Clarkson.