<font face="Verdana, Arial, Helvetica, sans-serif" size="2">I'm always astounded how, after travelling thousands of miles through unpredictable weather, the arrivals are so accurate. Don't forget the ETA is at the gate, so add another 10 minutes or so to the actual touchdown time.[/B]</font>
I think you mean subtract and not add (just to avoid confusion). I think that answer is stacking and circling. As I posted above, we could have landed a good half hour earlier but circled several times over the Kew area to land at 04.31 precisely: the first - and in T4 only - flight in of the day.