The way earthing works is it reduces the potential of the earthed item, or more exactly equalises any potential making the earthed item 'less visible' to an atmospheric charge. A good example of this is a yacht. My boat has a 45ft metal mast which you would think would be a massive lightning magnet - particularly in the waters around Hong Kong where it usually sails. However, the mast is earthed to the cast iron and lead keel by a 2" wide copper earth strap which from experience, works very well. Once, we had a lightning strike so close to the boat we could see the seawater boiling - but it didn't strike the mast. In the bay which it is moored, there are about 15 mono-hulls with keels and 5 catamarans - which don't have keels. The cats get struck regularly, but with the mono-hulls, it's very rare.
At HKG, the earthing of aircraft is mandatory.