This route must really be going badly for them if they're giving up two daily DCA landing slots and turning them back to the gov't.
Even if the loads aren't great, the yields on this route should be well above their system average. Also, they have the ability to connect passengers to LAS, LAX, and SFO via DTW. DCA-DTW should work for Spirit. Surprising to see that it doesn't.
I was under the impression DCA made them give up the slots... it was a part of their contract with DCA. I read an interview somewhere a few months back stating Spirit is breaking even/turning a small profit.
US applied for DCA-Pensacola (PNS?) and TZ also applied for MDW-DCA.