Abstract: Distributed monitoring systems and data synchronization methods are provided for monitoring a vehicle, such as a rotorcraft. One exemplary method involves a mobile device broadcasting measurement synchronization messages corresponding to a measurement window to measurement units onboard the vehicle over a wireless network, obtaining synchronization timestamp data corresponding to the measurement synchronization messages from each of the measurement units, obtaining measurement data obtained during the measurement window from the measurement units, and associating samples of measurement data from a first measurement unit with one or more samples of measurement data from a second measurement unit based on the synchronization timestamp data.