Virgin is dropping or suspending PHL. When Virgin first added PHL, it made the majors led by US lower prices on the LAX and SFO transcons. VX also offered connections out to other west markets like SEA and SAN.

That additional competition I believe did hurt Frontier originally in its connection efforts on PHL-DEN, as the connection market to the west coast diminished as flying a nonstop became more affordable. Virgin began in April 2012, and Frontier pulled out of PHL-DEN later that year. But that's just my theory.

It's going to be more expensive to fly nonstop to the West after Virgin leaves as fares were higher prior. Some passengers might be more inclined to travel up to EWR or will fly Southwest with a connection.

Will Frontier be more inclined to find a way to link TTN and/or ILG to the west coast, including ensuring ILG-DEN schedule is timed correctly for west connections and other strategies (maybe other TTN one-stops, ILG-LAX/SFO like 3-4x weekly each)? Let's hope.

Actually, it was dropping PHL service. Due to poor loads. That's why they couldn't make it. Too much competitive against US/AA, UA, DL & WN.

Not sure if you mean Virgin (in regards to PHL-SFO/LAX) or Frontier (in regards to PHL-DEN). Delta doesn't compete on either of these nonstop.

Either way, a lot of pax flying PHL-DEN were connecting to the West, when Frontier operated it and as Southwest and United operate it. When Virgin offered 5 r/ts to the West, and USAir lowered the prices, fewer pax needed to connect in DEN, so it was the weakest at the time, Frontier, that bowed out.

Southwest operates one PHL-DEN-SFO (no plane change) and demand will surge again on this route. Regarding Frontier now, my guess is this might help ILG-DEN frequencies and Frontier ensuring it offers connections to the West. It'd be nice if TTN was somehow involved. Maybe it does some TTN-CLE-West and adds PIT, and does TTN-PIT-West, but I'm not sure how it will do it, esp. with Frontier's move away from connections. Transcons from ILG directly like 3x to SFO, 4x to LAX would also be possible but be a bit more riskier.

PHL was dodgy for some time before Virgin came along, great in summer, miserable in winter. Except for DCA it applies to most of the DEN to the northeast routes, good in summer but thin in winter, and even DCA struggles a bit in January/February.

Originally operated as 2 x daily, DEN-PHL dropped back to 1 x daily when Southwest started the route, and then less than daily, in winter. When Frontier dropped it, they originally intended the drop to be seasonal, but then TTN and ILG happened.

Even so, I was surprised they kept ILG-DEN going through the winter but the very limited frequency and the lack of direct competition seems to have paid off.

I suppose they could restart DEN-PHL as summer seasonal, I'm just not sure why. I'd rather see TTN-DEN when they can get that sorted out.