Breaking waves play an important role in the transfers of momentum, heat and mass (gas, aerosols and spray) between the atmosphere and the ocean. They are the primary mechanism by which momentum flux is transferred from waves to currents. They are an important source of marine spray and aerosols in the marine atmospheric boundary layer and contribute to the flux of water vapor between the ocean and the atmosphere. Quantification of the role of breaking in all these processes is difficult and requires improved methods of measuring breaking at sea and relating it to specific processes of air-sea interaction. During the RED experiment off the coast of Oahu during August-September, 2001, we flew a Modular Aerial Sensing System (MASS) to image breaking waves and measure their kinematics and spatial statistics. In this paper we describe the techniques used to measure the fundamental distribution of lengths of breaking fronts per unit area of ocean surface as a function of the speeds of the whitecaps. We discuss the physical significance of the first five moments of this distribution in describing breaking statistics and for quantifying processes of air-sea interaction including, momentum, mass and energy transfer. We compare these measurements in RED off Oahu with comparable measurements during SHOWEX off the Atlantic coast of the United States.