Nothing special happens. If the flight crew didn't tell you about it, you wouldn't
notice anything. It's handy to know about it, though, because when you cross
the IDL traveling east, you're supposed to turn your watch and your calendar
back a day.
Alaska, USA is just east of the International Date Line.
East
If you are crossing date line from west to east you'll gain one day.
the international date line
International Date Line. Nominally 180 degrees east (or west) longitude. Opposite the Prime Meridian.
If you start at 177 degrees, 32 minutes, and 54 seconds West and you are traveling westward, you will NOT cross the International Date Line. You will cross it only if you travel East, at which point the coordinates from 177 degrees West will become 30 degrees, 12 minutes, and 11 seconds East longitude.
You don't gain a day by traveling West, only by traveling East. You lose a day going West.
Alaska, USA is just east of the International Date Line.
Nothing in particular happens; if you happen to be napping aboard the ship at the moment of crossing, you can sleep right through it, just as you do when crossing any other meridian of longitude. By international agreement, however, your calendar date becomes one less when you cross the International Date Line going east.
North America is on the east of the International Dateline.
If it is Thursday on the west side of the International Date Line, what day is it on the east side?
If it is Thursday on the west side of the International Date Line, what day is it on the east side?
If it is Thursday on the west side of the International Date Line, what day is it on the east side?
East
If you are crossing date line from west to east you'll gain one day.
You do not lose a day if you go from March 12 to March 11. You get to live March 11 again.
The International Date Line is an imaginary line of longitude of 180 degrees around the Earth. It works when a person crosses the line from the east to the west a day is added. The opposite effect happens when crossing from west to the east with a day subtracted.