Airborne laser profiles of swell entering the drift ice off the east coast of Newfoundland were made using a Geodolite profiler mounted in a DC-4 ice patrol aircraft. Concurrent infrared imagery along the track enabled the floe size distribution to be recorded. A linear decay of wave energy with 'effective penetration' (distance penetrated multiplied by fractional ice cover) was found, the decay rate increasing with wave frequency. A simple theoretical model based on progressive reflection from rows of floes gave good agreement with the observations.