Terminal Timezone
Logbooks could be complicated if time zones were observed when recording start and stop time, so regulations ask that logbooks are kept in the Terminal Timezone. A freight carrier with the main terminal in the Central Timezone should have drivers keeping time always in Central Time. Even after that driver crosses into Mountain Time, they should continue to record their Hours of Service in Central Time. A simple world clock application on a smart phone can assist a driver, as would a wrist watch set to Central Time.