Inmarsat D+ service is a short measuring service that offers advantages allowing for a small transceiver design. SkyWave Mobile, Inc. was contracted to miniaturize their first generation D+ transceiver, the DMR-200, to produce a 20 cubic inch device. This device, designated the DMR-400, incorporates an Inmarsat D+ transceiver, GPS receiver, antennas, I/O lines, and advanced power management into a 14 cubic inch unit. The DMR-400 has received Inmarsat land- mobile certification and will soon enter an aeronautical approval phase packaged in a radome housing. The first step in the aeronautical certification phase was the design of a radome and mounting kit for external mounting on an aircraft fuselage. This housing also incorporates a heating element to extend the operational temperature range to -55 degree(s)C. The assembled unit will soon begin DO-160 testing to be followed by Doppler correction testing, FAA flight-testing, and Inmarsat Aeronautical testing. The key to the entire process is the successful implementation of Doppler compensation based on the GPS data. The expectation is an FAA and Inmarsat aeronautical certified unit.