Abstract: A system and method for verifying ADS-B messages received at an aircraft from other aircraft within its ADS-B range. This disclosure enhances the current Automatic Dependent Surveillance-Broadcast (ADS-B) IN surveillance systems, and the disclosed system is an onboard system designed to enable ADS-B IN capable aircraft to verify the information received via ADS-B from the rest of the aircraft within its ADS-B range. The system's performance is based on the principles of multilateration (MLAT). The system performs MLAT calculations to determine whether the ADS-B messages received are truthful or not truthful. The disclosed system relies on a communication protocol based on a series of requests and responses to interchange the information needed by the aircraft involved in the process to carry out the MLAT calculations.