I spent 2 weeks on the island some years ago as a stopover while sailing from South Africa to brazil.
I was very surprised when I heard that an airport was to be built there as apart from the location chosen, there is no flat land large enough. The location chosen (ond only choice) is quite desperate as it is about 60 - 70° off in relation to the prevailing wind and surrounded by high cliffs on 3 sides. And it is quite a wind. They are trade winds which blow at around 20 knots at sea level, and much more up on top. Standing on the edge of those cliffs, you feel that you are about to take off and the turbulence is quite heavy.
About the ony good thing you can say is that the winds are very steady and blow consistently in the same direction, so there should be no surprises.
Quite how they plan to overcome the issue is beyond me.