Description / Abstract: DO-271C provides verification procedures for an aircraft Very High Frequency (VHF) Digital Link (VDL) Mode 3 Transceiver used for air-ground (A/G) voice and data communications. This revision includes updates based on changes to RTCA DO-224B, Signal-in-Space Minimum Aviation System Performance Standards (MASPS) for Advanced VHF Digital Data Communications Including Compatibility with Digital Voice Techniques, and includes errata and vocoder test vectors. This document supersedes DO-271B.