When an aircraft lands on a runway on which there are extensive puddles, it appears that sometimes the water exerts a large upwards force on the wheels, so preventing them from making contact with the ground. The wheels are then said to “aquaplane”. In the aquaplaning condition the braking effectiveness of the wheels is reduced virtually to zero, and even at touch-down speeds insufficient to cause aquaplaning, when there is some contact between the wheels and the ground, water on the runway may cause appreciable reductions of runway friction forces. This note offers some tentative suggestions concerning the nature of the water flow when aquaplaning occurs, and is put forward as a basis for discussion of this important practical problem.