In aviation, ground loop is the rapid circular rotation of an aircraft in the horizontal plane whilst on the ground. This situation, analogous to an automobile oversteering into a skid, causes the "outside" wing to rise, thus causing the "inside" wing to scrape the ground. In severe cases (particularly if the ground surface is soft), the inside wing can dig in, causing the aircraft to skid violently or even cartwheel.

Note: In tail dragger aircraft, the outside wing may dig in, due to the peculiar aerodynamics and centre of gravity; these aircraft are particularly susceptible to ground loop.

When ground loop occurs, it is usually in the context of an aircraft moving under its own power - either taxying, landing or during takeoff. Ground loop can cause extreme damage to the undercarriage and wingtips of an aircraft. Several incidents of ground loop have resulted in fatality.