We took off on Wednesday 19 May at 7PM from Beijing. At that time, Washington, DC was waking up for that same 19 May, 7AM.
Two hours later, as dinner was just finished, it was 11PM on Wednesday 19 May above Siberia: A dark night. Beijing was getting ready to go bed (9PM). At that time, the colleagues in Washington, DC were arriving in the office (9AM).
Four hours after departure, we had crossed midnight, and also the dateline, so it was 1AM, but on Wednesday 19 May again, above Alaska. Everyone was having sweet dreams on the plane. Beijing was sleeping too, towards the end of this same 19 May, 11PM. The colleagues in Washington, DC were getting ready for lunch (11AM). We were all on the same day.
Eight hours into the flight, we were above Northern Canada, zipping through the North American time zones through a fresh, but accelerated 19 May, at 9AM (Sun outside, but window shades down to keep the plane in an artificial night). Beijing was fast asleep (3AM on 20 May). The colleagues in Washington might have been sleepy too in the office despite post lunch coffee (3PM).
Ten hours into the flight, we were above Ontario, getting towards the sunset of this second 19 May of our lives, at 5PM. Beijing was about to wake up (5AM on 20 May). The colleagues in Washington were leaving the office (5PM). United Airlines gave us some food that they called lunch. I guess a compromise between the breakfast we should have had on Beijing time and the dinner we should have had on Washington, DC time. But it was neither one nor the other.
After twelve hours, we landed in Dulles, Washington DC. The local time and local date were the same as the departure (19 May, 7PM). Beijing was having 包子 breakfast under the shadows of the trees (7AM on 20 May). The colleagues in Washington were having dinner. We were on the same time zone now.