Text Box: Letter	Word	Difference
Y	Yankee	UTC - 12 hours
X	X-ray	UTC - 11 hour
W	Whiskey	UTC - 10 hour
V	Victor	UTC - 9 hour
U	Uniform	UTC - 8 hour
T	Tango	UTC - 7 hour
S	Sierra	UTC - 6 hour
R	Romeo	UTC - 5 hour
Q	Quebec	UTC - 4 hour
P	Papa	UTC - 3 hour
O	Oscar	UTC - 2 hour
N	November	UTC - 1 hour
Z	Zulu	same as UTC
A	Alpha	UTC + 1 hour
B	Bravo	UTC + 2 hours
C	Charlie	UTC + 3 hours
D	Delta	UTC + 4 hours
E	Echo	UTC + 5 hours
F	Foxtrot	UTC + 6 hours
G	Golf	UTC + 7 hours
H	Hotel	UTC + 8 hours
I	India	UTC + 9 hours
K	Kilo	UTC + 10 hours
L	Lima	UTC + 11 hours
M	Mike	UTC + 12 hours
The International Date Line is between
time zones M and Y (24 hours/one day differs) 

Time zone letter abbreviations

The basis for this is Z - Zulu time - Zero meridian time - the same as UTC

It's a convention to assign letters to time zones, where Z= Zero meridian, and Zulu is the word that represents the letter Z, when it's used in communication. It is sometimes used in the US Military and NATO in conjunction with 24 hour clocks, and is also popular to use in movies to reference time.

Other letters/words are used for other time zones than UTC, most based on the right or reverse order of the Alphabet. Note that 'J' is skipped ('J' - Juliet refers to current local time of the observer). There are 25 time zones defined here, but 26 letters in the English alphabet.