What does "Controlling Object" mean in FAA documentation? I was examining FAA's legacy files, which contain information for various airspace elements, and I noticed that there is a field in the airport layout file called "Controlling Object", for both base and reciprocal ends of the runway.

Some of its properties:


Controlling object description
Controlling object marked/lighted
FAA CFR Part 77 runway category
Controlling obstacle clearance slope
Controlling object height above runway
Controlling object distance from runway end
Controlling object centerline offset.


It seems that it's an obstacle near the airport, but I can not tell why it is more important than the others. Does it lead to the most adverse situation, as far as aircraft's climb gradient is concerned? Does also the term "Controlling Obstacle" exist?

Could someone point me in the right direction?
'Controlling object' is, as far as I can tell, the old term for 'controlling obstacle'.

From the TERPS manual (Appendix B):


  Controlling Obstacle. The obstacle on which the design of a procedure or establishment of a minimum altitude or angle is based on. See also Order 8260.19, Flight Procedures and Airspace.


Controlling object is mentioned as a field in the Public Use Airport Runways database:

Attribute_Label: BE_CTL_OBJ
Attribute_Definition:
Description of the controlling object at the base end of the runway
(e.g., trees, bldg, fence, none).
Attribute_Definition_Source: FAA
Attribute_Domain_Values:


And as you can see, it can be trees, a building, and so on.