As United rolls out the new international premium class product, some aircraft will have the new configuration and some will not — and the planes have very different configurations, very different number of premium class seats.

United is famous for aircraft swaps, unfortunately this has happened most recently with mainline A320s to TED (no first class) and before that it was downgrading regular 737s to old Shuttle aircraft that used to service the West Coast only. These aircraft swaps are disruptive, with different seating configurations. And ticketed first class passengers, in the TED example, go to an all-coach configuration. Not as big a deal on domestic routes as long-haul international.

But dropping 21 business class seats from the 747 has the potentially to be hugely disruptive. Either United will hold back most upgrades until the gate when it’s certain it’s running one of the old-style aircraft (bye bye advance upgrades) or it will be faced with significant at the gate downgrades (very unpleasant) when swapping out an old style aircraft with a newly confiugured one.

While I don’t ever bet on United’s savvy, I do think they’ll hold back upgrade availability… and then coach passengers looking to upgrade will be hoping for older aircraft once the renovations are underway because there will be much better upgrade chances.

Still, on some routes upgrades won’t be the issue. United will either be turning away paid business class, or potentially downgrading paid business passengers (though if first class seats haven’t been sold out, they’ll be managing the problem through operational upgrades).

A minor point, but a problem that United does at least have some time to work through.