This raises the very important question: is the fear of drones hitting planes completely overblown?
There is a reason why airports are very, very careful about the vehicles that drive onto runways - FOD (foreign object damage) is a very real thing with very severe consequences when a plane is on approach and take-off.
This often gets mentioned (and is obviously true) but I'm doubtful (but not certain) that it makes that much difference. Things we think about as "soft" can be remarkably hard at high velocity. At 120 mph terminal velocity, water and concrete are similarly fatal: the incompressibility matters more than the hardness.
This isn't to say that drone strikes are not an issue, only that I don't think they are significantly more of an issue than bird strikes. And birds can do a lot of damage at several hundred miles per hour. When you are hit by one, whether it's filled with bones or metal probably isn't the biggest concern.
And yet planes fly through clouds and rain at several hundred mph without issue, though the same wouldn't be said about flying through concrete...
The issue here is relative hardness. Bone is relatively soft to titanium turbine blades, whereas screws and titanium turbine blades are in the same ballpark of hardness, so are catastrophic when they meet when spinning @ several thousand rpm...
1) chucking a chicken bone into an insinkerator vs a penny.
2) a hunk of wood vs a hunk of wood with a nail through a wood chipper.
They shoot a frozen versus thawed chicken out of an air cannon, and conclude that the impact force is identical for both. I'm pretty sure that adding some metal bits inside both chickens wouldn't make much difference.
Density would make a big difference though. A basketball and a 1.75" lead ball have about the same mass, but the lead ball is going to do much more damage. But not because it's harder, but because it's dense and cohesive.
I'd guess that a drone of comparable weight to a goose is going to have a greater impact area, even though some of the internal bits are much harder, and I'd guess this is going to be more important for the level of damage.
Here's an article that supports that view that mass is the main factor: http://spectrum.ieee.org/automaton/robotics/drones/what-migh...
Here's more discussion (which I haven't read yet, and which may well contradict my instinct): http://aviation.stackexchange.com/questions/26223/would-a-dr...
Unlike birds, batteries by definition have a lot of stored chemical energy in them (1). in fact we want to put as much energy in as little weight as possible.
Violent disassembly by jet engine is not going to be a good combination with that.
1) https://www.google.com/search?q=hoverboard+catches+fire
It's possible that such a release could cause a catastrophic failure, but I have a hard time convincing myself that the battery poses a real risk.
Also, larger hobby aircraft (e.g. A 700-size heli) will be using battery packs on the order of 2x packs of 6 cells ("6s" aka 6 3.7v cells in series @4000-5000+ mah), so it's more like ~200-300Wh. Again though, doesn't matter, because even something like a 3s pack @2200mah can make quite a scary fire. This is why there are barrels of salt water at RC flying fields. An overheating lipo goes in the tank before it melts everything with hell fire.
Lipo fires are also why you can't take "hoverboards" on airplanes and why Amazon recalled them all: http://fusion.net/story/250086/airplane-hoverboard-ban-list/
http://www.theverge.com/2016/1/21/10806816/amazon-hoverboard...
Not sure how this is affected by being struck with a blade rotating at tens of thousands of RPMs at hundreds of miles per hour, but my point is that lipos are nasty beyond just their specific energy density :)
You can add as much regulation as you want, it won't change that it can be done the same way it already been done.
We don't know how large the drone was or what part of the aircraft it hit, for example what happens if one of the larger commercial drones gets ingested into the engine.
If you want to an example of what even a bird can do to a plane see this picture - http://i.dailymail.co.uk/i/pix/2016/03/13/12/3226FEF60000057...
The USAir flight that ended up in the Hudson river was disabled by striking a flock of Canadian geese (https://en.wikipedia.org/wiki/Chesley_Sullenberger)
But yeah, landing in a hailstorm with very little visibility is never real fun, but it's what instrument-flight ratings are there for.
If you're going to put an airplane down with no forward visibility, finding a 150' wide runway with CatIIIb/c minimums is probably the best you can do.
Links to KDEN's navigation data are on this Airnav page: http://airnav.com/airport/KDEN
Yes, this is part of the equation, but you also need to balance your efforts based on the "risk landscape". Spending effort in one place generally means that less effort is spent elsewhere. I think it's a direct parallel to optimizing code: measure first, then optimize. Making your inner loop 10% faster will make a difference, while speeding up your logging won't. Or vice versa, if you have no single inner loop and your logging is abysmally slow: measure first!
If it turns out that drones have 1000x the per impact likelihood of causing a fatality than impact with a birds, but that you are 100000x more likely to hit a bird than a drone, then are you better off spending your efforts on reducing the risk of drone impacts or bird impacts? Or (seemingly perversely) is it better just to tolerate both risks as they are if measurements suggest greater return by concentrating your efforts on improving airport security (or mental health checks for pilots, or testing English proficiency, or even traffic safety on the way to the airport).
In this case, my guess would be that adding regulations to reduce the risk of accidental drone strikes by aircraft will have negligible returns, that common sense "don't fly near airport runways" is sufficient, and that there is lower hanging fruit that makes more sense to concentrate on. Normal Accidents by Charles Perrow is an excellent book if you are interested in this topic: https://en.wikipedia.org/wiki/Normal_Accidents
First, effort allocation isn't really a compelling explanation -- most of the world just doesn't work in those types of zero-sum terms. Drones are sexy; just because government or industry is willing to fund research and development on safe drone-airplane regulations now doesn't mean it's willing to allocate those same resources to something else.
Second, even when resource allocation is strictly zero-sum, the sorts of calculations you suggest are mostly a matter of qualitative speculation about the future. Which means you're mostly just going through a number crunching process that "confirms" your prior beliefs.
> that common sense "don't fly near airport runways" is sufficient
I think the major challenge that incidents like this one demonstrate is that it might no longer be sufficient to assume pilots have common sense.
"And pilots have also called for the DoT to fund tests into what would happen if a drone got sucked into an engine or crashed into a plane's windscreen."
"Last month, the British Airline Pilots Association noted that while the threat of bird strikes had been well researched there was little data about how much damage a drone could cause a plane."
I wonder if any other organisations have conducted any rigorous testing?
Seriously, you're talking about hundreds of lives and a few hundred million dollars of equipment. Why do you want to take the one in a million chance?