Even at only 2 mph, the impact forces of such a heavy item like an aircraft, can cause interesting damage in the wing and to the mounting points.Ocap, you're right. Perhaps the word "unnecessary" should be added. Although I think not taking off pretty much ensures you won't crash. The Helsinki airport did have it's first airplane accident in something like ten years about a week or two ago. A plane was taxiing and bumped into the terminal at a whopping speed of 2 miles per hour.