Take notes at the time the incident occurs and jot down the names of the carrier employees with whom you dealt. Keep all of your travel documents (ticket receipts, baggage check stubs, boarding passes, etc.) as well as receipts for any out-of-pocket expenses that were incurred as a result of the mishandling. Here are some helpful tips should you choose to write a letter.

* Type the letter and, if at all possible, limit it to one page in length.

* Include your daytime telephone number (with area code).

* No matter how angry you might be, keep your letter businesslike in tone and don't exaggerate what happened. If the complaint sounds very vehement or sarcastic, you might wait a day and then consider rewriting it.

* Describe what happened, and give dates, cities, and flight numbers or flight times.

* Send copies, never the originals, of tickets and receipts or other documents that can back up your claim.

* Include the names of any employees who were rude or made things worse, as well as anyone who might have been especially helpful.

* Don't clutter up your complaint with petty gripes that can obscure what you're really angry about.

* Let the airline know if you've suffered any special inconvenience or monetary losses.

* Say just what you expect the carrier to do to make amends. An airline may offer to settle your claim with a check or some other kind of compensation, possibly free transportation. You might want a written apology from a rude employee or reimbursement for some loss you incurred-but the airline needs to know what you want before it can decide what action to take.

* Be reasonable. If your demands are way out of line, your letter might earn you a polite apology and a place in the airline's crank files.

If you follow these guidelines, the airlines will probably treat your complaint seriously. Your letter will help them to determine what caused your problem, as well as to suggest actions the company can take to keep the same thing from happening to other people.