My first concern when I heard of this idea was not the technological challenges (which can be met) but the cost factor. A signel quad delivers a single package and it takes time. So, you can only deliver enough packages in the day as you have quads available, so perhaps ten or so trips per day per quad. And given the cost per quad, it will have to be a premium delivery charge for this kind of air mail to make it cost effective for the company. You also have a limited area you can serve, so your available market is highly limited. Payload capacity is low, further limiting your market.
I would imagine, then, that this kind of delivery would only be requested when the purchaser absolutely needs delivery within an hour or two. That, too, restricts the market size. The fortunate thing (for Amazon) is that customers having such urgency are usually willing to pay for the quick response.
I personally would think that hiring someone with a bike to courier the package to the destination would be more cost effective. But you never know. If the cost of the quad itself can be made low enough, the economics shift and the approach could actually become economically viable, but still only for a very limited market. Don't expect to see these things being used frequently, if they ever do get used.
"The telephone will never be practical. You would have to run wires to everyone's house and that would be impossible."
Actual quote from the mayor of NY after a demonstation of the telephone in 1876.
The point is, what looks impossible now, may not be in the future. Drones could have counter-measures built in, like a mosquito, to avoid would be swatters. It could even have artificial intelligence to select best landing sites.
I used to read about flat-screen TV in the 60's but I never really thought it was practical. You would have to run million of wires internally to each and every pixel. How would you be able to do that and assure every connection was perfect?
But engineers found a way. I still can't believe it and I have one!
Jeff Bezos, in my opinion, is a visionary that far exceeds all others. I'm sure he is well aware of the issues and will find a way to overcome them. Whenever he sets out to do something, he usually succeeds so I'm betting drones will be routine in a decade or so.
Amazon will need to use differential GPS. Probably with the user doing a "self-tag" for where he wants the package delivered. An app could be developed to run in a cell phone to read offsets from a local Amazon beacon transmitter and the internal GPS receiver in the cellphone. Send all the appropriate data in an encrypted email to Amazon. Or maybe Prime users can mount a beacon device on an elevated delivery platform to guide the copter for the last 100 feet. (All good so far.)
Viola, before you knew it, another cracker attack vector. Making and operating a counterfeit Amazon delivery drone to harass people will become the new "swatting" technique. Or a way to drop mini-bombs or bags of burning dog-crap on your hated neighbor's front door step.
Amazon octocopter maintenance better be excellent or people will be finding dead ones in random places all over.
If I find one in my backyard, do I have to send it back to Amazon on UPS or FedEx? Or will Amazon send another "tow-truck copter" to fly it back home?
What if my dog chews the hell out of it? Anything in the backyard, on the ground is the dog's new chew toy. He loves toys that make whirring noises.
If I didn't order anything from Amazon, can I use a baseball bat to knock the thing down for violating my back yard's airspace?
I use Amazon a lot but I don't like the idea of thousands or hundreds of flying delivery obstacles in low airspace. It's bad enough I have to keep an eye on where I put my feet. WIll I have to keep an eye on the surrounding airspace as well?
The real difficulty in near surface navigation is utility lines, guy wires, etc. This is a general difficulty of personal flight applications. Look up sometime at the maze of urban connections. My neighbor was killed several years ago in a helicopter accident. The pilot became fogged in and was following a highway. Landing skid snagged an electric wire. End of the road.
Short of Google mapping the power, cable, and telephone grids, I'd like to see how they solve this one. (We don't have the imaging capability. There are thousands of changes daily. Even the utility companies don't have complete and accurate information.)
There may be a functional limit on homeland drone incursions after all...
FAA issue is simply keeping them from crossing airfield with control towers (commercial airfields). The general aviation airfields is just another problem to work through. This is what the FAA is working on. The operating height is not an issue since the general aviation height requirments and this would not overlap except in the area of a general aviation airfield. Navigational issues are another non-issue. GIS is a major technological inovation that every level of govnerment has invested in. So getting to wherevere is not the technical problem that some of 'engineers' here think it is. The end user is expected to be at the point of delivery so the criminal conduct has automatically escelate past petty theft to robbery. I doubt I am going to see an increase this activity as well as someone stepping out spur of the moment and discharging there firearm another felony. No, the disruption factor will be in the area of keeping high mainteance vehicle usage minimized. What is the head count and expense of operating one package truck. I'm certain Bezos already knows this. QVC, EBay, and company won't be that far behind. Including UPS and FEDEX.