How should the call sign S21523 be pronounced?

The call sign S21523 is pronounced as "Sam Two One Five Two Three." This pronunciation method follows the phonetic alphabet approach commonly adopted in aviation and air traffic control communications, where specific letters are associated with distinct words to ensure clarity. In this case, the letter ‘S’ is represented by the word ‘Sam.’

Using the phonetic alphabet helps to reduce misunderstandings that might arise from similar-sounding letters or numbers when transmitted over radio or other communication channels. The additional numbers are pronounced straightforwardly, allowing for quick and accurate identification of the call sign among pilots, air traffic controllers, and other personnel involved in aviation operations.