The angle of approach is the maximum angle between the horizontal plane and the plane tangent to the outer rim (dead) of the front tire. The front axle of any fixed to the vehicle's rigid components shall not be below this plane.
The larger the approach angle is, the less likely the vehicle is to have contact accident when driving in the field, and the better the vehicle's passing performance is
A Departure angle is the angle between the road surface and the leading tangent of the wheel from the rear-end protrusions of a vehicle when it is fully loaded and at rest, this is the maximum angle between the horizontal plane and the plane that cuts the outer edge of the vehicle's last tire (dead load) . Any rigid part fixed to the vehicle behind the last wheel must not be below this plane. It represents the ability of a car to leave obstacles (such as hills, gullies, etc.) without collision. The greater the departure angle, the better the vehicle's trafficability.