There is a discount fare window for travel with many alliance airlines for departures from Thanksgiving Day November 26 to December 15, 2016. This period between the two major U.S. holiday weeks is one of the slowest air travel periods of the year for U.S. traffic and a great time to find airline ticket discounts.
New York and Washington are two airports showing competition among the major alliances for routes to Europe. Star Alliance looks to have the most widespread deals and overall lowest fares on most of these routes. There is some competition with Oneworld and SkyTeam on other routes, particularly where they are protecting their own London and Paris traffic.
Amsterdam $440, Brussels $443, Manchester $525, Munich $530 round trip. LOT Polish has a $468 round trip fare from New York JFK to Belgrade that is not being challenged.
New York has more routes on sale than Washington.
New York City Airports to Europe Star Alliance fares Nov 28 – Dec 5.
$478 Belgrade, Serbia (LOT Polish via Warsaw)
$583 Madrid, Spain (many cities in Spain are in $500s flying TAP Portugal)