The first field phase of the multi-year Eastern Pacific Investigation of Climate Processes in the Coupled Ocean-Atmosphere System (EPIC2001) was conducted in September of 2001. This multi-platform experiment included aircraft and ship borne measurements anchored by surface data collected from the 95 West TAO buoy array. During the program numerous vertical profiles of temperature, humidity, wind speed and direction were conducted to help characterize the large study area. Three techniques were primarily used to provide these profiles: "in-situ" aircraft measurements; NCAR/Vaisala GPS dropwindsondes deployed from the aircraft platforms; and Vaisala rawinsondes with GPS tracking launched from the ships. This paper provides a detailed review of the precision and relative accuracy of the GPS dropsondes deployed from the NCAR C-130 aircraft and the "in-situ" data collected by that platform. In order to then place these measurements within the overall context of the project, selected profiles are compared to data obtained from rawinsondes launched from the NOAA ship Ron Brown.