9 ms·

I was wondering about the time zones mentioned in the article? If SFO/T-7 is 7 hours behind Greenwich Mean Time and LHR is in the (same) GMT time zone, how is

• vinay427 6y ago
  It's really poorly phrased in the article but I assume what they meant is that LHR is in a time zone that sometimes observes GMT, and otherwise observes BST (British Summer Time) in the summer which is 8 hours ahead. It's not exactly correct that SFO is 7 hours behind GMT because this isn't true for around half the year. It also isn't exactly true that LHR is in GMT. Most of the year, SFO is actually 8 hours behind LHR. A few weeks are off due to different DST dates.
  • PuddleOfSausage 6y ago
    The author/editor has mentioned elsewhere in this thread that he was using dummy data (which contains mistakes). For this dummy December flight LHR would be in GMT (UTC+0) and not BST (UTC+1).
• fraculus 6y ago
  GMT doesn't observe summertime, but LHR does. So LHR (and the rest of Britain) is only in the GMT time zone for half the year.
  • azalemeth 6y ago
    GMT is very nearly the same thing as UTC. Think of it as a reference rather than timezone, but one that happens to be used by a few places half the time. It's just easier to think of yourself in UTC/GMT all the time (known as Zulu time or /Z in the aviation world) and deal with the relative offsets later. Don't forget that US Daylight Saving has different start/end dates to the UK while you're at it too...