The ability to operate when runways are flooded or slush-covered to some degree, must be demonstrated during the certification programme of any new civil transport aircraft. Failure to meet the requirements laid down will result in operating restrictions which may jeopardise the sales prospects of the aircraft. Most other types of aircraft will also have to operate occasionally in these adverse conditions.

The main problems result from the spray generated at the wheels, and are engine malfunction due to spray ingestion and damage due to its impingement on the airframe. An associated problem is the packing of slush into ducts, flap cavities, undercarriage bays, etc, with the attendant risks of damage to internal systems and jamming of mechanical parts. There is also a large additional drag load on the aircraft, due to the displacement of fluid by wheels and to spray impact on the airframe: this increases roughly in proportion to the depth and effectively limits the slush depth that can be tolerated on the runway. For many aircraft this limit is little more than one centimetre.