text: Intermediate 
  Will we soon live in a world where drones deliver packages? If you believe Amazon, the answer is yes. Others are not so sure: we need to make more technical progress in this area but there is also the problem of public safety.
  Amazon spokesman Paul Misener told a US congress hearing recently that his company would be ready as soon as all the rules were in place. The Federal Aviation Authority (FAA) will  nally have regulations on the commercial use of unmanned aircraft by June 2016. But the technology has a long way to go before then and larger machines arent legal yet  only drones up to 25kg will be legal. And the FAA says that, if youre going to crowd the skies with radio- controlled  ying robots, they must all use different radio frequencies that nobody can jam or hijack.
  Professor Sajiv Singh, who runs a cargo delivery company called NearEarth, said that, to pilot a state-of-the-art drone, you simply give it some basic instructions: go to this altitude, perform this short task, go back home. But even short  ights from a mobile landing pad could cause serious logistical problems, he said.
  Theyre not going to deliver from one uninhabited place to another uninhabited place; theyre going to deliver from a warehouse to the consumer, which will probably be an urban area or a suburban area, he said. In those particular cases, there are going to be hazards that the vehicle is going to have to see. Maybe there will be terrain that the map doesnt know about. Then, maybe theres construction equipment that wasnt there before but is there now. Maybe GPS signals are blocked, in which case its going to have an incorrect idea about where it is. All these problems can be solved, he said  but its dif cult.
  One major problem is maintaining radio contact with a drone and planning for what happens if that contact breaks. If you have an off-the-shelf UAV [unmanned aerial vehicle], itll just keep going and crash into the ground, said roboticist Daniel Huber.
  Furthermore, you cant do everything with a 25kg aircraft, said Jay McConville, director of business development for unmanned systems at Lockheed Martin. People in the aircraft business have to remind ourselves that the operator doesnt really care about every little thing about the aircraft and wants instead to focus on the end result, he said. Operators want to see vehicle status information; they want to see video on their handheld device or their laptop.
  Technologically, most of the things that we need for this are in place, said Huber. He is working on a program to allow drones to inspect infrastructure  pipelines, telephone lines, bridges and so on. Weve developed an exploration algorithm where you draw a box around an area and it will  y around that area and look at every surface and then report back.
  Huber, who works on 3D systems imagery, said about Amazon: I have heard them say that many packages are lightweight  a drone can carry a kilogram for 15 minutes. If you have a vehicle that can go into a neighbourhood, it can deliver from that base. You need a 15-minute distance and typical off-the-shelf drones have that distance. Its one way, he said, of making sure the surrounding population is relatively safe. The larger you get, the more dangerous you get.
  Problems with the use of drones can be solved in some very dramatic ways, Huber said. At a recent conference, he said, a disaster relief drone company demonstrated a robot that could take off and, when it got tired, land on its own charging station and exchange its batteries.
  Of course, safety is still a major concern  Singh says that, for a commercial aircraft to be allowed to  y, it has to prove a rate of one serious failure every one million hours. Drones, he said, are a long way from that. The Reaper drone has one failure in 10,000 hours, Singh said. But they dont consider an oil leak a catastrophic failure  something has to fall out of the sky.
  Part of the reason for this is that air travel is dangerous so standards are much higher. If you  y commercial airlines, they often say, Oh, a component has failed  we have to go back to the gate, Singh said. And thats an established industry with 60 years of legacy! I hate to think that a drone might come down on a busy road. Part of the solution, Singh said, is planning for every situation: If things fail, the vehicle has to do something reasonable.