UK Law
In the UK, in Bernstein of Leigh v Skyviews & General Ltd [1978] 1 QB 479 it was held that a (manned) plane overflying properties (once) and taking a photo (one) was not trespass (they were selling the owners photos of their houses from the air, in pre-Google days). It overturned the previous (13th century) maxim Cujus est solum ejus est usque ad coelum et ad inferos (for whoever owns the soil, it is theirs up to heaven and down to hell) for the air, saying instead that property owners only have rights over the air above their property to such height as is necessary for the ordinary use and enjoyment of his land. There are earlier cases - in 1815 it was decided that floating across land in a balloon wasn't trespass, nor was firing a bullet across it (unless it landed or hit an animal).
The court did say that if a claimant was subjected to the harassment of constant surveillance from the air, accompanied by the photographing of his every activity then that would be a "monstrous invasion of privacy" and an actionable nuisance (for which damages would be given). Nowadays the Data Protection Act 1998 rights would also apply.
Overhanging cranes can constitute trespass and it is common for crane operators to get a licence from neighbouring owners.
More generally, the relevant Air Navigation Order 2009 (SI 2009/3015) imposes rules on flying in congested areas or within 50m of any person. Breach of the ANO is a criminal offence for which people have been prosecuted.
s.76 of the Civil Aviation Act 1982 imposes liability for any damage caused on the ground (if the drone crashes into your greenhouse). That was for manned planes but it is thought to extend to drones. Also Regulation (EC) No 785/2004 requires all commercial air operators (including drones) to have insurance. Private model aeroplanes have an exception.
Biting the hand that feeds IT
