Originally Posted by
MSPeconomist
D1 is business class, not FC. The OP specifically talked about a FC ticket.
I don't think DL serves Mexico, Central America, or northern South America from SEA, so that leaves the transborder Canadian flights as eligible for SC use with a FC ticket.
I don't think they make and listing of First Class anywhere. So international First Class may not count.
http://www.delta.com/content/www/en_...of-terms.html#