5) Trespass to Airspace

There is an old Latin maxim of the common law (cujus est solum ejus est usque ad coelum) which suggests that the possessor of the surface of land also has possessory rights to all that lies below the surface and to all the airspace above it. That maxim warranted little attention and gave rise to few disputes for centuries. It was only with the advent of air travel in the twentieth century that it became necessary to balance the interests of the possessor of land to his airspace with the legitimate interests of others in the use of that airspace. The new principles to achieve this balance of interests have not as yet been fully and authoritatively worked out but it appears that the courts are differentiating among three kinds of interference in airspace: permanent intrusion into airspace at a relatively low level, temporary intrusion into airspace by means other than by aircraft, and intrusion by aircraft.

There is a great deal of judicial consistency in respect of permanent low-level intrusions into airspace by signs, billboards, hydro-lines, and parts of buildings which project over the plaintiff's property. Intrusions of this nature are actionable trespasses to land, and compensatory and injunctive relief are available without proof of damage. [Note 124: See, for example, Didow v. Alberta Power Ltd. (1988), 88 A.R. 250 (C.A.) [Didow].] Some municipalities take advantage of this rule and levy an "intrusion fee" on retailers who put up advertising signs that project over public sidewalks.

The law relating to the temporary intrusion into airspace by means other than by aircraft has developed largely in respect of cases dealing with the use of cranes on construction sites. It is not uncommon in the construction of high-rise buildings for the booms of construction cranes on top of the structure to swing through the airspace of the adjacent owner. Construction companies normally secure a licence to use the neighbour's airspace but sometimes the negotiations for a licence are not successful. An adjacent owner may, for example, attempt to exploit a strong bargaining position and demand an excessive sum for the privilege of using his airspace. In that situation, the contractor may be tempted to proceed without a licence, thereby prompting the neighbour to sue for trespass to airspace. There is some unevenness in the judicial response to this issue. Some courts have held the intrusion to be a trespass and have issued an immediate injunction prohibiting the use of the crane in a wrongful manner. [Note 125: See, for example, Lewvest Ltd. v. Scotia Towers Ltd. (1981), 126 D.L.R. (3d) 239 (Nfld. S.C. (T.D.)).] Some courts have taken the same position but have suspended the operation of the injunction until completion of the building project. [Note 126: See, for example, Woollerton & Wilson Ltd. v. Richard Costain Ltd., [1970] 1 W.L.R. 411 (Ch.).] Another option is to remedy the intrusion by an award of damages which may be calculated nominally or on the basis of a reasonable charge for a licence. Other courts have suggested that such an intrusion ought not to be regarded as a trespass at all and that the appropriate remedy is in negligence and nuisance, both of which require proof of damage. [Note 127: Didow, above note 124.] The weight of authority, however, is that the intrusion into airspace by the boom of a crane is a trespass. This permits an appropriate remedy to be sensitively tailored to the surrounding circumstances of the individual case, including the reasonableness of the plaintiff's behaviour in refusing to give permission.

There is also a variety of possible approaches in respect of intrusion by aircraft. One approach is that intrusion by aircraft is not a trespass at all and that the landowner is restricted to a remedy in negligence or nuisance. The second approach is that intrusion by aircraft is a trespass subject to a privilege of reasonable and legitimate flight. [Note 128: There is some support for this view in Atlantic Aviation Ltd. v. Nova Scotia Light & Power Co. (1965), 55 D.L.R. (2d) 554 (N.S.S.C.).] This approach requires a balance to be drawn between the interests of the surface owner and the use of the incumbent airspace by others. Most recreational, military, and commercial flight would be privileged but flight for the purpose of photographing private property, spraying a powerful insecticide over an urban area, testing military weapons, advertising products or services, or conducting surveillance may give rise to some difficult issues. [Note 129: This approach, which seeks to balance the interests of the surface possessor with those of others who seek to use the airspace, echoes the approach of Laskin C.J.C. in Harrison.] The third view, which probably represents the current Canadian position, [Note 130: See Didow, above note 124.] is that trespassory remedies are available only for intrusion by aircraft within the surface owner's zone of effective possession. Effective possession is an elusive concept but the general idea is that it extends to a height necessary to protect the plaintiff's current or future enjoyment, comfort, or use of land. The zone of effective possession will in most cases be no more than a few hundred feet above the ground. Above that, the remedy must be sought in negligence or nuisance. [Note 131: For a subterranean trespass to land, see Austin v. Rescon Construction (1984) Ltd. (1987), 45 D.L.R. (4th) 559 (B.C.S.C.), varied as to damages (1989), 57 D.L.R. (4th) 591 (B.C.C.A.).]

CHAPTER 4, INTENTIONAL TORTS