With a strike deadline of 9:01 PDT tonight for Northwest Airlines and its mechanics union, travelers could be caught in a mess, although Northwest says it has elaborate contingency plans, including hiring other mechanics, to keep planes flying on a regular schedule.

Here's how to prepare:

• Canceling/changing flights: If you want to change or cancel a flight before any strike begins, contact Northwest customer service to see if penalties would be waived. So far, the answer has been no. "Because Northwest plans to continue to operate our full normal schedule of flights, each ticket's normal fare rules will apply," the airline said.

The usual penalty is $100 plus the difference in cost between an old and new ticket. It is possible Northwest might waive penalties closer to the deadline, so keep checking. But if you hold a mileage-award ticket, you can cancel or make changes for $25 to $50.

• Checking on flights: Reconfirm your flight 24 hours ahead and, if a strike begins, check its status before leaving for the airport. Sign up for e-mailed flight-change notification at www.nwa.com. If a strike begins, it may be hard to get through on the customer-service phone line, 800-225-2525. Be aware Northwest is changing its flight schedule. The airline is implementing its fall schedule, with reduced flights, on Saturday, roughly a week sooner than usual (airlines reduce flights after the summer peak season). That will mostly affect smaller cities.

• If your flight's canceled: Although Northwest vows it will maintain regular flight operations, if there is a disruption, the carrier says it will accommodate passengers in several ways. "Examples include the waiving of fare rules, rebooking passengers to other Northwest flights, allowing the refund of nonrefundable tickets and in some cases, re-booking passengers on other airlines' flights," the airline said on its Web site.

Make sure you have an extra copy of your e-ticket (or paper ticket) in case you need to transfer to another airline.

• Seattle impacts: Both domestic and international flights may be affected by a strike or lockout. From Seattle, Northwest has flights across the country to Minneapolis, Detroit and other Midwest and East Coast cities. It also has popular Seattle-Hawaii flights and international service to Seoul, South Korea; Tokyo, Amsterdam and more.

• Insurance: If you insured your Northwest trip before July 19, you will be covered against trip interruption, cancellation and delay in the event of a strike. Since July 19, when the strike countdown began, no travel insurer has written a policy against this Northwest risk.

• Backup car rental: If you could drive to or from your destination instead of flying, reserve a car at the airport in case your flight is canceled. You can always cancel the car rental.

• Backup flight: If you must fly somewhere, buy a second ticket on another carrier as backup. Look for an airline that has few advance-purchase rules so that you can cancel or change it if needed.

• Children flying alone: Do not send a minor to wait for a flight alone at an airport gate in case there are delays or cancellations. Get a pass from airline staff that lets you accompany the child through security to the gate, and stay there until the flight has left. Be wary about sending a minor alone on connecting flights if there's a labor disruption.

Northwest has been quietly rebooking some unaccompanied minors due to fly soon. Spokesman Scott Tennant said the airline wants to be extra careful when it comes to children traveling alone during any potential work stoppage.

• Getting more information: To ask questions of Northwest, try e-mailing. For details, go to www.nwa.com/talk/ttu.html">www.nwa.com/talk/ttu.html. Or call the airline at 800-225-2525, but be ready to wait. Northwest is posting information about the dispute on the Web at www.nwa.com/features/laborqa">www.nwa.com/features/laborqa.

Information from the Detroit Free Press, Arizona Republic and Seattle Times travel staff writer Kristin Jackson is included in this report.