It's Still the Same Old Story

The European Union and the United States have virtually identical rules about liquids, except for the unique provisions the E.U. has made for duty-free products sold in specially sealed packages inside the secure area of the terminal.

It's no problem if you leave from an E.U. nation, land in the United States and leave the airport. But if you are taking a connecting flight inside the United States, your Scotch and any other duty-free liquid/gel/aerosol will be confiscated, E.U. seal or not.

4. Being involuntarily bumped from a flight and then not being able to use the airline's voucher for a subsequent flight.

Example: The airline oversold my flight, and I got bumped. They got me on a later flight and gave me a voucher that seemed like a good deal at the time, but now I can't redeem it for the times and places I want.

If you're involuntarily bumped, you've got rights under rules set by the U.S. Department of Transportation. If the airline can't get you on a flight scheduled to arrive within one hour of your originally scheduled time, you're entitled to payment, in addition to a later flight.

If the substitute flight is scheduled to arrive one to two hours later than originally scheduled -- or up to four hours later on an international flight -- you're entitled to a refund of your one-way fare, up to $200. If the substitute flight is even later than described above, compensation doubles.

The airline might offer you a voucher that's worth much more than the cash, so weigh your options and pay attention to restrictions on the vouchers. Some must be redeemed as if they were frequent-flier awards. Cash vouchers are best: They can be used the same as cash, without restrictions.

5. Delayed flights.

Example: My flight was delayed for six hours due to a mechanical problem. The airline didn't give so much as a sandwich, let alone a voucher for a free trip. I thought they were required to compensate me for my time.

No. Passengers see freebies being handed out when people are inconvenienced by being bumped and then assume inconvenience is a cause for compensation. But federal regulators are basically silent on any delays not caused by bumping. The only compensation you can expect is what individual airlines promise in their contracts of carriage. Most promise only that if the delay was their fault and if your delay is overnight, they'll pay for a night's hotel -- as long as the airport where you're stuck wasn't your point of origin.

If your flight is delayed, find out as quickly as possible -- use a cellphone to call the airline if you're standing in line to talk to an agent -- what alternative flights are available so that you can ask for a particular flight. First, check flights for the airline on which you hold a ticket, including connecting flights or alternative airports that the agent might not think about.

Second, if your airline will let you fly on an alternative carrier with which it has agreements, check what the alternative airline has going. Does your airline allow agents to put you on another carrier? The rules, which are in each airline's contract of carriage, vary a great deal. Northwest Airlines is generous: If it cancels a flight or changes a schedule by more than an hour, or if it causes a missed connection, agents can put you on another carrier. JetBlue promises to put you on another carrier at your request. Southwest, AirTran and Spirit: Forget about it.