With two recent work trips and a five-city European vacation, combined with the changes to summer time in the US and Europe, I’ve gone through quite a few time zone changes in the past six weeks.

I wanted to find a good way to visualize this, and I ultimately decided on the following format:

Time zones can be challenging to represent, so let’s start with talking about UTC.

UTC (which superseded Greenwich Mean Time, although for our purposes they’re interchangeable) is the time zone of the prime meridian, and it does not change for summer time. UTC is used in situations where an unambiguous, continuous reference time is necessary. For example, flights are scheduled in UTC to avoid confusion about time zones and summer time – effectively, UTC is aviation’s “official” time.

The time zones we’re familiar with (for example, Eastern Standard Time or Eastern Daylight Time) are then represented as differences from UTC. Eastern Standard Time is five hours behind UTC – that is, when it’s 11:00 AM in UTC, it’s 6:00 AM in Eastern Standard Time. Thus, EST is UTC minus 5 hours, written as UTC–5. In the summer, Eastern time shifts an hour forward to Eastern Daylight Time, so EDT is only four hours behind UTC, or UTC–4.

So when I’m flying around between time zones (or switching to Daylight Savings Time), I’m really just changing the number of hours I am ahead of or behind UTC. So for any given moment in time (as represented by UTC, I can plot my offset from UTC.

Thus, in the above chart, the horizontal axis represents UTC, and the vertical axis represents the number of hours I’m offset from UTC. Every horizontal gridline represents a one hour shift. The colored bars represent time I spend in a time zone, and the dark gray lines between them represent travel.

So, for example, when I flew from Reykjavík to Chicago, I had to set my watch back by five hours (as I traveled from UTC+0 to UTC–5).

You can also see from the chart that I went through two shifts to summer time: I was in the US when they changed to DST on 13 March, and I was in Europe when they changed to summer time on 27 March. In each case, my watch had to move an hour forward, even though I didn’t travel anywhere.

Incidentally, with all this talk about UTC and Greenwich Mean Time, I’m happy to report that my Europe trip included a visit to the Royal Greenwich Observatory in London, which is the point that defined both the prime meridian and Greenwich Mean Time!

2015 was a relatively strong year for me for business travel, with the first and last thirds of the year being particularly busy. Due to that, my total flights and hotel nights just edged above 2014’s numbers, for another record year.

2015 Flights

I had 89 flights this year – 79 for work and 12 personal.

I didn’t take as many personal flights this year, but travel for my job more than made up for the difference.

2015 Hotel Nights

That’s not to say that I didn’t do a lot of personal travel, but a lot of those personal trips were by car. I came out with 30 personal hotel nights and 79 business nights, for a total of 109 nights.

New Airports

I’ve visited six new airports this year:

• Little Rock – LIT
• Vancouver – YVR
• Toronto (Pearson) – YYZ
• Wichita Falls – SPS
• Colorado Springs – COS
• Nashville – BNA

I ended the year with 60 total airports visited, and am well on my way to my goal of visiting 100 airports.

Elite Status

My flights were much more spread out among airlines this year, so I ended up getting the lowest tier status on two airlines (Gold on American Airlines and Silver on United) rather than last year’s mid-tier status on one airline. For hotels, I was easily able to pick up the 60 nights required for Diamond status with Hilton, and I even managed to pick up enough Marriott nights to get Silver. (Last year, my United Gold status gave me Marriott Gold status as well, even though I barely stayed with them.)

Trivia

• Longest Flight: SEA – CLT (2,279 mi)
• Shortest Flight: DFW – SPS (113 mi)
• Lowest Altitude Flight: SPS – DFW (0 feet above ground level)