Every piece of real estate has three separate and distinct physical elements: the subsurface, the surface, and the air space. The owner of the land acquires title to the land in conjunction with title to the underground space and the space above it.

Air rights mean the estate, title, interest and rights in the open space or vertical place above ground level. Any ownership of land includes the ownership of air rights, which are subject to reasonable aircraft interference.

The air itself is not real property; airspace, however, is real property when described in three dimensions with reference to a specific parcel of land.

Air rights are alienable. They can be sold, purchased, mortgaged, leased, or otherwise encumbered. Obviously, the alienability of air rights is greatly impaired by easements of light and air.

Examples of the possible alienation of air rights are a condominium unit, which involves the ownership of a certain specified layer of air space, and an aviation easement, which is the right granted to aircraft, generally when approaching an airport, to fly at a stipulated altitude over certain specific land.

The following are the most common methods:

• A lease of air rights above a fixed plane, together with the air and ground necessary for the foundations of and access to the airspace structure.
• An aerial easement. This method is generally used in the construction of elevated highways.
• By purchase of the fee of ground and air space with reservation of easement by the grantor.
• By purchase of the fee of air space plus easement for support and access.
• By purchase of the fee of air space and purchase of fee of support parcels.
• By purchase of the fee in condominiums.

• Fee title, or
• Leasehold, or
• An easement, or
• A determinable fee.

• Insurable legal description 
  
  An air space description is always extremely difficult and complicated to draft. Only local experts should attempt such a task. The qualifications and expertise of the drafter must be beyond doubt and reproach. 
  
  Any air space description must also encompass the tracts describing the easements of support and access.
  
  
• Is the interest to be insured recognized as valid in the relevant state under common law or under statute?
• Is the estate recordable under applicable recording acts?
• Are there special recording requirements?
• Are there specific means of support?
• Are there specific means of access?
  Mention needs ot be made that access can be achieved through either:
•     A fee, or
      An easement, or
      A leasehold, or
      A license, or
      Any combination thereof.    
• That any access through a leasehold estate would be dependent upon the termination of the leasehold
• That any access through an easement would be dependent on any limitation on the easement.
• That any access through a license would be dependent on the conditions of the license.
• Mortgages, easements, restrictions, and other liens and encumbrances affecting the subjacent parcel prior to its division.
•     Leases affecting the subjacent parcel prior to its division.
• Mechanic's liens based upon work done or materials furnished to the subjacent parcel prior to its division.
•     Compliance with zoning regulations.
•     Compliance with subdivision acts.
• Do statutes contain any provision for separate taxation of an air parcel?
• If the air space is over a railroad, does the railroad own the fee title?
• If the air space is over a street or highway, who owns the fee title?
• If the air space is over a navigable body of water, who owns the fee title?

Insuring title to air space separated from the title to the soil is undoubtedly an extrahazardous risk. 

If the air space is part of a condominium unit, please review the section on Condominiums. 

In any other case in which the estate to be insured is a space above the surface of the property, specific approval must be obtained from Texas Underwriting Counsel before issuing any title commitment or title policy.

Please note that in some wind farm transactions, easements or restrictions are created to provide for an uninterpreted flow of wind to the windmills and turbines.  Exception must be taken to such easement or restriction.  Call an underwriter before also insuring such an interest.