My understanding was that US Airways wasn't using its two gates in Terminal D for the number of daily departures required under their leases, so the airport ended up taking back the gates. Of course, it would have been easy enough for US to put a half-dozen daily flights at each gate so there had to be some reason they gave up the gates.
To quote the Philly Inquirer story from September 28:
"At the airport, officials said yesterday that they had told US Airways that they wanted to reclaim two gates in Terminal D that the airline had not been fully using and had been on month-to-month leases."
The same story does state that US missed its August rent payment to the airport as well (and owed the city about $4 million).
I'd surmise that WN
would (for now) mostly use those gates for evening arrivals with few connection possibilities and morning push departures.
As far as I know, most (or all) of the gate leases at PHL
expire in 2006. If US Airways survives until then, it will be interesting to see how everything gets reallocated then.