One does wonder how much clearance
The typical sort of heavy departure with a significant V1/Vr split using maximum clearway can raise the eyebrows for onlookers ...
One can't see the runway here
http://www.strangemilitary.com/image...ent/167533.JPG but, presuming it to be in frame, you get the idea ...
All fine and according to Hoyle. Providing that the conditions reasonably replicate the certification testing the takeoff is sensibly repeatable. From this point, the obstacle clearance gets progressively better away from the runway due to the better gross compared to net gradients. Indeed, fleet data will provide a small additional benefit.
The need is for the ops engineers to know their business, do it accurately and well .. and for the crew to fly iaw the book.
For very close in obstacles (first segment or early second segment) the clearance can be minimal and approach 35ft ... from there on it gets better.