What time is it right now? Look at your watch or your phone. Your answer will likely differ from mine and others, even if we are all checking at the same moment in time. Think about the strike of midnight on New Years Eve, marking the turn of the new year. Everyone in the world doesn’t celebrate the ball drop at the same moment in time. The Earth spins, and thus we have time zones. Even beyond time zones, you have standard time and daylight savings time, and then some areas that don’t recognize daylight savings time. “Its five o’clock somewhere,” right? To get us all on the same page, there is a time that is used in aviation and meteorology that provides stability for various time zones. That time is Zulu time, and right now is a good time for us to dig a little more into it.
A Simple History
Zulu time is also associated with Universal Time Coordinated (UTC) and Greenwich Mean Time (GMT). When the powers that be created the concept of time zones, it was determined that the Greenwich Observatory in England was the starting point. Time zones were then referenced as hours plus or minus GMT. UTC is a more precise time that can be considered the same as GMT, unless you are a scientist, in which case you would surely point out the minor differences using atomic clocks and the earth’s rotation. For our purposes, though, we’ll use Zulu, GMT and UTC interchangeably.
When you tell a friend to meet you for coffee at 7am, it’s hard to get that confused. Friends rarely drive across time zones to meet for simple things like coffee, especially that early. In aviation, time zones are frequently crossed, so to make sure everyone is on the same page, time is referenced in Zulu time. Weather briefings and forecasts, METARS and flight plans all reference Zulu time. By everyone translating their local time to Zulu time, everyone is speaking the same language.
Get In The Zone
Zulu time uses a 24 hour military style clock, meaning that 1500Z is the equivalent of 3PM in Zulu time. I live in Georgia, which is currently Eastern Daylight Time. This means my time zone is UTC-4. To reference 1500Z from where I am, I subtract 4 to find that my local time is 1100, or 11AM. In the spirit of the phonetic alphabet, each time zone has a letter to reference it (Alpha, Bravo, Charlie, etc.) on up to Zulu. Juliet doesn’t have a time zone, which is a tragedy, given that Romeo has one, but you don’t often hear the time zones referenced by their letter other than Zulu, which is Z in the phonetic alphabet.
Learning The Language
Thinking in Zulu time is a little like learning a language. If you haven’t had much practice with thinking first in 24 hour military time, it’s a bit of a double conversion. It’s easy enough to for me to know that right now at my home airport, I’m UTC-4. I can see 2300Z, subtract 4 hours to get 1900 and then convert from military time to get 7pm. That works just fine with some practice, but it can still get confusing when lots of Zulu times are being thrown out, like a Terminal Area Forecast.
A New Tool For Your Toolkit
Thankfully, one of our Clayviation subscribers has developed an app to help us out. It’s called Time Table, and it’s a simple tool that you can have in front of you to easily convert a barrage of Zulu times to your familiar local times. Take a look at it in action. Here is an example of a Terminal Area Forecast (check out how to read a TAF here). I’ve bolded all of the Zulu times.
311739Z 3118/0118 27005KT P6SM SCT045 BKN120
FM311900 28008KT P6SM VCSH BKN050
TEMPO 3120/3124 VRB12G20KT 4SM -TSRA BKN030CB
FM010000 28004KT P6SM SCT030 SCT250
FM010300 28003KT P6SM SCT250
FM011000 32003KT P6SM FEW250
Now with this screenshot of the app with Eastern time up, see if it helps to reference the chart when you read the times in the TAF above.
The app is only $1.99 and you can purchase it here. As Clayviation subscriber, you can grab a promo code to get the app completely free for the week that this blog launches (May 31-June 6, 2017). If you are already a subscriber, simply reply to the weekly email that you would like the code and I will personally send you your own unique code. Otherwise, subscribe at the link below and I’ll send you your unique code to redeem the app.
The app developer has a limited supply of codes, but even if they run out, I’ll contact you with instructions on when and how you can get yours.
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