I spent a great deal of time around DIA yesterday and noticed that there was a British 777 sitting at the UA hanger all day. I'm not sure when it left, or if it is still there because I had to "take-off" so-to-speak. 

Anyhow, what does BA do with this when they want to put the a/c back on route to London? I would figure that another BA 777 arrived, as usual, last night. So do they spread-out the pax on both airliners back to LHR?

Anybody care to add their two cents worth of how this usually works?

And, I almost forgot, what was the deal with the sitting 777?