This shows the Boeing factory determining the demonstrated crosswind landing limits on the 777 and the 747SP. The engineers make educated guesses, but then the test crews have to go actually prove the numbers. They sneak off to Brazil to do these tests at a certain remote BAFairbase famous for its continual atrocious crosswinds...Should the gear side loads be excessive and fold one up there is nobody there to take nasty pix for the Airbus guys to wave around in the press.
This is some good piloting in getting these planes down.
Next time your plane comes down sideways, you won't have to worry as much. Especially those SouthWest planes going to Vegas all day long.
http://www.motochat.com/videos/Crosswind_.wmv