How do you write a block altitude on the strip?

Writing a block altitude on the strip requires indicating the range of altitudes that an aircraft is cleared to operate within. The correct format is to always list the lower altitude first, followed by the higher altitude, which clearly indicates the operational limits for the aircraft. This avoids any confusion regarding the intended altitude range.

In this case, if the block altitude is between 100 and 150, writing it as "100B150" appropriately reflects the lower altitude first (100) followed by the higher altitude (150). This format emphasizes clarity and ensures that all involved in managing air traffic can readily understand the altitude range being referenced.

This approach aligns with standard aviation terminology, making it widely accepted and understood within air traffic control operations. Other formats that reverse the order of the altitudes or present them in an unstructured way could lead to misunderstandings regarding the intended flight path and safety of the aircraft in question.