In the early 1990's, I lost about 3,000 miles in my America West account. (I'm a little vague on this, but I think miles were only good for two or three years, after which they expired, regardless of whether you were still "active" or not.) I clearly remember three things about this experience:

1. When my miles DID expire, there was no special notice or anything. They just quit sending statements, and in those pre-internet days I had to make a phone call to learn that the mileage had disappeared.

2. When I learned that my miles had expired, and tried to get America West to reinstate these miles, they ignored all my letters and phone calls.

3. Over the past ten years I have successfully avoided doing business with America West, largely because I couldn't see taking the risk of losing miles again.

I realize that things are different today, but since there is so little experience with the current three-year expiration policy I thought some past history might be useful.