Q. My friend is flying on April 15th (Friday) from Beijing to NewYork with Air China.
The flight leaves at 9:00AM, and arrives in New York at 10:20AM.
His question is regarding the flight route – is there a possibility that he will be flying over any area that night (or at least Shkia) which means that it’s Shabbos, and does that have any ramifications on him?

A. A direct flight from Beijing to JFK is about thirteen and a half hours long. Due to the spherical structure of the planet, the short route taken usually is over Wrangel Island, Beaufort sea and Alaska.
Approximately after four or five hours of flight the airplane should be exiting the continental Russian Federation and thus crossing the Chazon Ish dateline, from Friday into Thursday. Since the time at that area (aprox. 70.0 N – 175.0 E) is probably four hours later than Beijing and over four hours probably have passed since the flight started, the local time at the crossing should be between 5.00 or 6.00 PM. At that latitude on April 15 it should still be before the shkiah. (8.25 PM)
The next Halacha dateline to be crossed would be the Bnei Tzion – Atzei Hassade dateline, which is close to the international dateline (aprox. 177 E according to Bnai Tzion). This would be taking into account the added travel time on about 6.30 PM or 7.30 PM. still before the shkia.
Crossing the Sefer Hayoman dateline (144.8 W) would take place about four hours later around 10.30PM – 11.30PM local time, taking into account traveling time and zone time change. According to this opinion, some traveling may occur after the shkia, (9.47 PM at 70N – 144.8 W,) before crossing back into Erev Shabbos.
Al the times quoted are only very rough approximations since the actual departure time, airspeed and route taken may vary.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a