Originally Posted by stephem

Sorry, I had AA on the brain ;-)

I often see DL with similar clauses in their cheap fares. For ex-SEA Y-up fares they routinely specify the fares are not valid for any of the SEA-JFK-SEA lie flats.

Sometimes the fare rules specify certain aircraft that cannot be used, other times they specify routings where there will almost certainly not be a lie flat. AA/DL also do this on YVR-BDA, YVR-SJU and other similar bargain basement fares that could allow a cheap lie flat transcon to be had.