An altimeter setting must be issued to an en route aircraft operating below FL180 at least how many times in your area of jurisdiction?

An altimeter setting must be issued to an en route aircraft operating below Flight Level 180 (FL180) at least once during the flight. This is important for ensuring that the aircraft maintains proper altitude during its journey, as accurate altitude readings directly impact safety and traffic separation.

When an aircraft is operating below FL180, it is typically within controlled airspace where standard pressure settings may not be applicable. Issuing an altimeter setting helps pilots adjust their altimeters to the current atmospheric pressure in the area, allowing for accurate vertical navigation.

The regulation mandates that this information is provided to pilots to minimize the risk of altitude deviations, which could lead to dangerous situations such as terrain conflicts or airspace violations. Ensuring that pilots have the correct altimeter setting, at least once, is a critical aspect of air traffic control duties to maintain safe operations within the airspace.