How is an altimeter reading of 30.00 inches of mercury transmitted in an observation?

An altimeter reading of 30.00 inches of mercury is transmitted in an aviation weather observation using the format that begins with the letter "A" followed by the altimeter setting expressed in inches of mercury without the decimal point and any leading zeros. Therefore, the correct transmission format would be "A3000," indicating that the altimeter setting is 30.00 inches of mercury.

In this case, "A" indicates that the information pertains to altimeter settings, while "3000" represents the value of the setting, derived from multiplying the inches of mercury by 100 (30.00 inches becomes 3000). This specific format ensures clarity and consistency when communicating crucial altimeter information within aviation operations, allowing pilots and air traffic control to quickly and easily interpret the data.

Other options either format the altimeter reading incorrectly or include characters or sequences that do not conform to standard aviation communication practices.