Several international airlines posted advisories on their Web sites regarding extra screenings and carry-on bags for international U.S.-bound flights, saying that the U.S. government's revisions have prompted changes for passengers flying to the United States.

CNN: Canada limits carry-on baggage on flights into U.S.

Although jets are pressurized so that the cabin environment resembles an altitude of around 8, 000 feet, some people report that flying (possibly from the changes in pressure and resulting decrease in oxygen concentration) causes symptoms such as headache, fatigue and nausea.

CNN: Is it OK to fly after a head injury?

He changes camera speeds, zips through sequences, sends things flying through the air.

NEWYORKER: Millions

Advances in cockpit technology have all but eliminated traditional threats such as jets flying into mountains in bad weather or slamming into the ground because of sudden wind changes on approach.

WSJ: The New Frontier in Air Safety

With so many changes and lots of choices, how do you know if you're flying with the right program?

FORBES: Most Rewarding Frequent Flier Programs

Flying in formation, they could map the gravitational field of an asteroid or moon by monitoring tiny changes in their relative positions.

ECONOMIST: Picosatellites