Answer:
A domestic air carrier airplane lands at an intermediate airport at 1815Z. The latest time it may depart without a specific authorization from an aircraft dispatcher is 1915Z (1 hour).
Explanation:
Under the domestic operations, an airplane landed on intermediate airport can remain their for not more than one hour so the time would me 1 hour.
Here the time represented by 1815Z and 1915Z is in Zulu Time Zone as depicted from letter "Z". The first two digits represent the hour (0-24) and the next two represent the minutes (0-59).
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