Originally Posted by
Wycombe
Both airports now operating at or near capacity?
Look at what happens operationally to either if anything (even relatively minor, like strong winds dictating greater separation) affects the arr/dep rate?
All of those comments are perfectly correct.
But think about it. An additional runway, at either airport, only makes business sense if a decent ROI can be achieved, in other words if you can utilise it adequately by attracting sufficient new traffic. That's a lot easier to do if the other guy is still capacity-constrained.
If both airports were foolish enough to go ahead simultaneously with a new runway, they would be slugging it out for many years to come in competition with each other and both would struggle to get an adequate return on investment.
Both Gatwick and Heathrow CEOs have said as much in the past. You could argue that that's just posturing, but they aren't stupid.