Unmanned aircraft are slowly penetrating various areas of human activity, but how far are we really from the future world of drones?
It seems a drone mania is taking the world by storm. Following the example of e-commerce giant Amazon and German logistics firm DHL, further companies have recently proposed various applications for unmanned aerial systems. But as the technology becomes more widespread, its shortcomings become increasingly obvious.
From sensible attempts to use drones for environmental monitoring, inspection of high-voltage power lines or gathering video footage of traffic jams to outright bonkers ideas such as carrying mistletoe branches above the heads of dining couples, drones seem to offer something to everyone.
Latest on the UAV bandwagon is the Mayor of London Boris Johnson, who has called for London's tech companies to develop personal drones to collect of parcels and groceries. The technology, Johnson believes, could help relieve congestion in the capital, for which, the Mayor said, delivery vans are largely responsible.
Johnson's vision of smartphone-controlled drones crisscrossing the world's largest metropolises resonated with researchers presenting their technology at the RE.WORK Future Cities Summit in London in early December.
"We hope that smart drones will be the next trend; maybe they will have their own Facebook apps so that no one could live without them any more," said Bart Remes, from the Delft University of Technology, the Netherlands, at the summit.
"Instead of taking selfies, people will be taking dronies, you would be able to take a picture of yourself from above while engaging in various activities with your friends for example," Remes explained, demonstrating some of his team's inventions: tiny pocket drones, no larger than a human palm and weighing around 20g while being equipped with cutting-edge sensors.
However, the spread of the technology is slowly uncovering major challenges.
The mistletoe-carrying drone in one fancy New York restaurant crashed into a woman's face causing a painful injury when its pilot tried to land on her hand.
A far more serious, potentially deadly, incident involving a remotely piloted aircraft was described by the UK Airprox Board, a leading aviation safety authority, in a recent report.
In July this year a pilot of a British Airways operated Airbus A320 with 180 people aboard spotted a remotely piloted quadcopter dangerously close to the aircraft while approaching the runway at London's Heathrow Airport.
The UK Airprox Board said the drone, flying at 700ft, was invisible to air-traffic control radars, and its owner was never identified.
The incident, rated as an A on a five point scale, meaning the highest level of collision risk, sparked a flurry of voices calling for stricter regulations and better technology to control the booming UAV sector.
"Common air-traffic control radars are designed for detecting, surveying and tracking large aircraft at ranges of many hundreds if not thousands of kilometres," Peter Doig, a defence technology consultant at Plextek Consulting told E&T.
"They are not designed to look for something like a quadcopter or a small one- or two-metre fixed-winged aircraft, which could comfortably fly at 700ft. These UAVs have very small radar cross-sections as they are predominantly made of non-metallic materials, such as plastics, which don't have a very big return from radar."
However, technology firms including Plextek are already trialling novel radars that could help air-traffic controllers keep track of remotely piloted intruders in sensitive airspace.
"We have developed a system based on electronic scan frequency modulated continuous wave Doppler technology that can detect small unmanned aerial systems such as quadcopters or a two-metre fixed winged aircraft up to a distance of 20km," Doig explained.
"We have done trials both in the UK and internationally and we have demonstrated the system can even distinguish drones from birds to reduce false alarm rates," he said.
An alternative system, known as the 3D holographic radar developed by Cambridge-based technology firm Aveillant, has already been tested at some airports in the UK.
However, even the most sophisticated monitoring systems won't protect from irresponsible handling. In fact, under regulations issued by the UK Civil Aviation Authority (CAA), small UAVs not equipped with radar transponders and thus not visible to conventional air-traffic control radars can only be flown legally within segregated airspace or within the line of sight of the operator up to a maximum altitude of 400ft.
The vision of the future world where everyone has his or her personal drone for running errands gets more complicated. Currently, the CAA limits the use of drones over densely populated areas for safety reasons, issuing permits on a case by case basis.
While feather-light drones, like those presented by Bart Remes may be perfectly safe even if crashing on someone's head, bigger devices, such as those designed to carry parcels, could be dangerous, not only if an accident happens but also through intentional misuse by terrorists.
In the wake of the Heathrow incident, the British Airline Pilots Association (Balpa) called for tougher regulations that would require anyone operating a remotely piloted aircraft to undergo pilot-equivalent training.
So far, anyone can buy and fly a drone for anything between a couple of hundred and a couple of thousand pounds.
"I don't believe that drone delivery in large cities such as London will happen very soon," said Mirko Kovac, director of the Aerial Robotics Laboratory at Imperial College London at the RE.WORKS Future Cities summit in London.
"But I believe it may come really soon in the developing world, for example in Africa, to deliver goods and medical supplies, like blood," he said.
In cities there are large buildings, there would be other drones which could collide with each other, there would be crowds of people walking below. Integrating drones into the city traffic would certainly be challenging,
But these concerns are unlikely to stop those who have just caught the drone fever.
In September, the US Federal Aviation Administration (FAA)loosened restrictions on UAV use, granting exemptions to a group of television and movie production companies to use drones largely for non-news-gathering purposes.
The FAA said general guidelines for broader commercial use of drones weighing up to 25kg may be put in place during 2015.
Like them or hate them the drones are certainly here to stay.