You miss your connection.

What happened: On a trip with a connection in Atlanta, your incoming leg was delayed, so you missed your onward flight — which, of course, was the last one of the day.

What the airline should do for you: If the delay was the airline’s fault (a mechanical problem, say), request overnight lodging and a meal voucher, plus transportation to and from the hotel. Ask nicely — and out of earshot of other passengers, as the airline may not have enough accommodations to go around. Note, however, that there is no law requiring the airline to grant your requests. And if the delay was beyond the airline’s control (the result of bad weather or air-traffic congestion), then you may simply be out of luck.

Next time: If possible, don’t take a flight with connections if there’s a nonstop available. “There are more problems and interruptions with connecting flights,” says San Francisco travel lawyer Alexander Anolik. “If you must take one, start your journey first thing in the morning, since earlier flights tend to experience fewer delays.” In addition, the on-time performance of every domestic flight in the United States is tracked and is available from either the airline or your travel agent. Flights are rated on a scale of 0 (on time 0 to 9.9 percent of the time) to 9 (90 to 99.9 percent). By avoiding flights with poor ratings, you increase your chances of arriving on schedule.

If you absolutely must arrive on time, give yourself some wiggle room. For example, instead of allowing just 40 minutes to make your connection at a large and busy airport, leave yourself two hours. Also, while en route to your first stop, check the in-flight magazine for a map of the terminal at which you’re landing—a big help in finding your way to the next departure gate.

The fare goes down after you’ve bought tickets .

What happened: You bought a ticket for $400, and the next day the fare dropped to $200.

What the airline should do for you: Usually airlines will let you trade in your tickets for the cheaper ones, though generally there is a change fee. And sometimes that fee — up to $200 per ticket for international flights — will be greater than any savings.

Next time: Fly an airline that doesn’t levy a large change fee in such cases — or take Southwest, which doesn’t charge one at all. Also, try to “buy at the bottom” in the first place by checking such sites as Fare Report.com for the historical average of fares along the route you’ll be flying.