In the military they use the phonetic alphabet and military time.

The phonetic alphabet are words used to spell out letters whilst communicating over radio or telephone to help be clear and accurate during communication especially in noisy areas.

The military operates at all hours of the day and night, so it uses a 24-hour clock, commonly referred to as military time, to avoid confusion between a.m. and p.m. hours.

Phonetic Alphabet and Flags

Helpful tip:

To convert from standard time to military time, simply add 12 to the hour. So, if it's 5:30 p.m. standard time, you can add 12 to get the resulting 1730 in military time. To convert from military time to standard time, just subtract 12 from the hour.