What is the correct way to state an altitude of 4,500 feet MSL to ATC?

When communicating with Air Traffic Control (ATC), clarity and adherence to standard phraseology are essential for ensuring safety and reducing misunderstandings. The correct way to state an altitude of 4,500 feet MSL is "Four thousand five hundred."

This method is preferred because it breaks the number down into clear and distinct units that are easy to understand over the radio. Saying "Four thousand five hundred" ensures that the receiving controller comprehensively understands the altitude being communicated without confusion over numbers that can sound similar, especially in a noisy cockpit or when using radio transmission.

Using other methods such as "Four thousand five" may lead to ambiguity, as it could be interpreted as either 4,500 or 4,050 feet. Similarly, using “Four five zero zero” introduces unnecessary complexity and is not the standard phraseology. "Fifteen hundred" is a completely different altitude (1,500 feet), which does not correspond to the altitude in question.

In conclusion, stating "Four thousand five hundred" maintains the standard communication protocol and minimizes the risk of misinterpretation, which is crucial in aviation communication with ATC.