Seasonally. Starting next May. Interesting announcement, for a couple of reasons, which we’ll get to.

But first some context. US Airway’s summer 2010 European flying and such, by aircraft type, with summer seasonal routes in italics. This matters, as US Airways only has a limited number of aircraft that have enough range to fly to Europe:

A330-300 (293 seats)(9 aircraft): CLT – London Gatwick; CLT – Frankfurt; CLT – Rome; PHL – Frankfurt (2 daily); PHL – Rome; PHL – Madrid; PHL – Manchester, England

A330-200 (258 seats)(7 aircraft): CLT – Paris; PHL – Paris; PHL – London Heathrow; PHL – Munich, PHL – Tel Aviv (requires two aircraft)

767-200 (204 seat) (10 aircraft): CLT – Honolulu; CLT – Rio de Janerio (requires two aircraft); PHL – Venice; PHL – Athens; PHL – Zurich; PHL -Barcelona; PHL – Dublin

755-200 (176 seat): PHL – Lisbon; PHL – Glasgow; PHL – Oslo; PHL – Brussels; PHL – Amsterdam

Now US Airways has said that they want to start flying to Sao Paolo, Brazil in January on a 767-200, which requires two aircraft. Then there’s Charlotte-Madrid, which is set to run May 4 – Oct. 29, 2011 on a 767. Dublin, on a 757, will run from May 6 – Sept. 30, 2011.

So where does US Airways get enough planes — 3 767s to be specific — to fly all the routes they’ve announced? Great question. Where two are coming from is obvious: CLT – Honolulu flopped, and was discontinued back on Aug. 1. The airline can also put a 757 instead of a 767 on PHL-Dublin. This especially makes sense with it also adding CLT-Dublin. But to find the third 767 requires either dropping an existing route or increasing aircraft utilization above what they’ve traditionally been willing to do.

The next step: Note that US Airways is shifting strategy a bit. Until 2008, its focus was using its limited number of available aircraft to add flights from Philly to second-tier destinations in Europe. Now the focus seems to be more on adding a second flight (this one from the Queen City) to the larger destinations.

In that context, the two new European routes come as little surprise. Madrid is served daily from Philadelphia on US Airway’s biggest jet. Dublin is within 757 range from Charlotte, which makes it doable. It also doesn’t hurt that passengers clear US immigrations and customs in Dublin, so the jet can use a domestic gate when it arrives here in Charlotte.

After that though, the possibilities for additional European service from Charlotte are limited. Manchester may be doable on a 757 from CLT. It’s certainly that only destination that gets an A330-300 from Philly that isn’t also served from Charlotte. Pretty much everything else is too far for the 757 and would require an A330 or 767. And it’s not as if US Airways is doing so well in Brussels, Amsterdam, or Zurich, that it can justify a Charlotte flight and a Philly flight, even if it had the planes. Which it won’t until 2013, when it’s scheduled to receive five more A330-200s.