In an attempt to defend its territory from discount airlines such as Air Tran and Southwest, as well as start-ups like Independence Air, United Mileage Plus is offering members who originate or terminate their travel in either Washington D.C. (at Dulles or Reagan) or Baltimore the chance to earn a free ticket for completing just two roundtrips.

Hold off on that appointment to renew your prescription, you read right. United is now awarding one credit for every segment on a ticket that costs more than $100 in and out of the two cities, and members who earn four credits (two roundtrips) earn a free regional domestic roundtrip ticket in economy class.

What better way to fend off the competition than to offer a free ticket for completing just two roundtrips?

A domestic roundtrip ticket can be earned by accruing eight credits. Twelve credits will earn an economy-class award trip to Hawaii or the Caribbean, 16 credits will net an economy-class ticket to any international destination served by United, and 24 credits will entitle the holder to an economy-class award ticket good for travel around the world.

If you prefer to see the world from the front of the plane, 48 credits will buy you a first- or business-class seat.

The around-the-world award ticket must be booked seven days in advance and requires a Saturday-night stay, which, if you’re traveling around the world, you’re bound to come across somewhere. And chances are, you’ll probably be planning seven days in advance.

The aforementioned requirements are easy to live with; the toughest condition to abide by is the one that says once you’ve begun traveling in one direction, you must continue to go the same direction. No backtracking or meandering in another direction will be permitted. In addition, all award travel must occur by Dec. 24, 2005.

Regional, domestic and international award tickets must be booked online. Qualifying travel may be booked in any published fare in United First (F, A, P), United Business (C, D, Z) or United Economy class (Y, B, E, M, U, H, Q, V, W, S, T) on United, United Express or Ted flights only.

Registration is required at http://www.united.com. To keep tabs on your accrued credits, visit http://www.united.com/viewatw.