https://en.wikipedia.org/wiki/Coordinated_Universal_Time#Time_zones https://en.wikipedia.org/wiki/Coordinated_Universal_Time#Tim... > ... or by the letter Z—a

https://en.wikipedia.org/wiki/Coordinated_Universal_Time#Time_zones https://en.wikipedia.org/wiki/Coordinated_Universal_Time#Tim... > ... or by the letter Z—a reference to the equivalent nautical time zone (GMT), which has been denoted by a Z since about 1950. ... Since the NATO phonetic alphabet word for Z is "Zulu", UTC is sometimes known as "Zulu time". https://en.wikipedia.org/wiki/Nautical_time https://en.wikipedia.org/wiki/Nautical_time > Around 1950, a letter suffix was added to the zone description, assigning Z to the zero zone, and A–M (except J) to the east and N–Y to the west (J may be assigned to local time in non-nautical applications So, yes, all three are the same. You might like this - https://books.google.com/books?id=MJYc-6eqT8AC&pg=RA2-PA1&q=nautical%20time%20zulu https://books.google.com/books?id=MJYc-6eqT8AC&pg=RA2-PA1&q=... - a USAF major in 1959 complaining about the switch to "Zebra, err, I mean Zulu time kick." (And complained about switching from mph, which was good enough for the Wright brothers, to knots.)