This unadvertised sale is back on again! Similar to a sale that we posted a few weeks back, it looks like Delta and SkyTeam partners are undercutting United hubs in the US to StarAlliance destinations in Europe. These amazing fares can be had beginning at $436-8 to Brussels & Zurich, and $504-6 to Frankfurt & Vienna.

Since it is unadvertised it may not last very long. Book quickly if something catches your eye. Most third-party booking sites have a 24-hour free cancellation policy so you'll have a day to figure out the details.

Travel is available on a wide range of dates, but generally through mid-May and from mid-August through October. Travel Monday through Thursday, with the occasional Sunday departure available, 21-day advance purchase and a 7-night minimum stay is required. Most of these are main cabin fares, which means your first checked bag will be included as well. Click on the fare details for more booking information.

Fares include:

Baltimore to Brussels $436 round-trip

Washington DC-Reagan to Brussels $436 round-trip

Washington DC-Dulles to Brussels $436 round-trip

Houston-Hobby to Brussels $436 round-trip

Chicago-Midway to Brussels $436 round-trip

Chicago-O'Hare to Brussels $436 round-trip

Denver to Brussels $436 round-trip

San Francisco to Brussels $436 round-trip

San Jose to Brussels $436 round-trip

Newark to Brussels $440 round-trip

Baltimore to Zurich $438 round-trip

Washington DC-Reagan to Zurich $438 round-trip

Washington DC-Dulles to Zurich $438 round-trip

Houston-Hobby to Zurich $438 round-trip

Chicago-Midway to Zurich $438 round-trip

Chicago-O'Hare to Zurich $438 round-trip

Denver to Zurich $438 round-trip

San Francisco to Zurich $438 round-trip

San Jose to Zurich $438 round-trip

Baltimore to Frankfurt $504 round-trip

Washington DC-Reagan to Frankfurt $504 round-trip

Washington DC-Dulles to Frankfurt $504 round-trip

Houston-Hobby to Frankfurt $504 round-trip

Houston-Bush to Frankfurt $504 round-trip

Chicago-Midway to Frankfurt $504 round-trip

Chicago-O'Hare to Frankfurt $504 round-trip

Denver to Frankfurt $504 round-trip

San Francisco to Frankfurt $504 round-trip

San Jose to Frankfurt $504 round-trip

Washington DC-Dulles to Vienna $506 round-trip

Houston-Bush to Vienna $506 round-trip

Chicago-O'Hare to Vienna $506 round-trip

San Francisco to Vienna $506 round-trip

Newark to Vienna $513 round-trip

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