How do you start fallout 3 operation anchorage?

from the Fallout 3 site

http://fallout.bethsoft.com/eng/info/faq.html

How do I start Operation: Anchorage?

Once your content has downloaded, you should be able to access Operation: Anchorage from any current save file for Fallout 3. Once you've loaded a game save, you should receive a Pip-Boy message stating:

Alert!: A new radio broadcast has been heard across the Capital Wasteland. It sounds like a distress call, but seems meant for certain ears only. Following this, you'll get a quest notification for "Aiding the Outcasts." If you make this your active quest in your Pip-Boy 3000, your World Map will point you to where you need to go.