Why we can't stop birds downing aircraft | Hacker News Reader

Why we can't stop birds downing aircraft

newscientist.com

24 pointsalexandros53 comments

I wonder if selectable inertial separator would work on turbofans. (They are installed on single-engine PT-6 turboprops.) Imagine a system that requires air to make a sharp turn, but anything with significant mass (water, ice, birds) would pass through, or get ground up against something other fan blades. I couldn't find a good diagram online.

You would want them to be selectable (engaged during low-altitude flight, stowed during cruise flight) so as to hopefully not unduly hurt range, other than via the increased weight.

The problem though is that there are significant one-engine-out climb performance targets that must be met for Part 21 certification, and inertial separators have power penalties on top of the weight penalty. Taking performance away from a one-engine-out scenario would further restrict max take-off weights, increase balanced field lengths (meaning some airports would need to make improvements to serve some aircraft, etc), increase the time from roll to V1 (the takeoff commit speed) and at the end of the day, taking performance away may represent a higher risk than birds currently represent.

In 700 hours or so of single-engine piston flight, I've struck two (small) birds, and had close calls with half-dozen more. I've never had a close call with a bird over 2000 feet AGL, so cruise flight could surely be done without brid protection.

Taking performance away also directly impacts the bottom line of airlines and airplane manufacturers, so highly unlikely.

So does dunking a $60mm jet in the Hudson River. :)

If the airlines have heavier (but safer) planes their costs go up. If they lose a plane it's probably their insurance company that pays for it, I'd think. Maybe their premium goes up though? Wouldn't be the first time people's lives were on the bad end of a cost/benefit analysis.

Hypothesize two airlines, one flying current airliners and the other flying airliners that are 0.5% safer and whose tickets are 5-10% more expensive.

Who do you think gets all the business on competing routes? Filling even 5% more seats on average dramatically improves airlines P&L statements.

I'm not saying it's rational, but big businesses have been built on the inability of the average person to do math. (Airport insurance kiosks, lotteries, pachinko parlors, or Las Vegas/Macao.)

(I'm also not suggesting that there's an easy way to get that 1 in 200 improvement in safety, even at a 10% cost penalty, but if your airline gets a reputation for bad safety, you're all but done, even if you come up on the top of Expedia/Travelocity/ITA searches when sorted by price...)

Which is one of the reasons the FAA exists. It's probably not the best idea to let airline safety get sorted out by market forces.

If market forces increased the number of deaths from air travel by .5% for 10% off ticket prices, I don't think that would necessarily be a bad thing. There's value in cheaper travel, and it might even be value that saves a life -- granted, the kid in Africa who died this morning of starvation because his mother is unemployed because his country is not a tourist destination because it costs too much to go there did not die in a photo-friendly fireball, but is his death any less meaningful?

LOTS of very useful things will kill far more people this year than commercial air travel. Water buckets. Bicycles. Doctors. Cars, in about the first two hours of the year.

(If you took a Boeing 747 full of American patients to a doctor's office, more than one would die due to medical error. Remember that checklists article from yesterday?)

Air travel gets the evil eye because the deaths are very visible. The same factor would make market-regulated air travel very safe.

Bonus points for explaining how market forces would encourage surgeons to use checklists.

"This is your malpractice insurance company. We just read an interesting article in the newspaper about how using checklists cuts fatalities by 50%. So we checked our data, and found this is accurate. Great news!

If you don't use checklists, your premium next year will triple."

Cool. Now, what are the pitfalls?

Note that the parent comment to yours mentioned an example where letting the market sort out airline safety works. Your comment suggests that you believe people should be forced by the FAA to travel on lower cost airlines even if they would avoid them due to poor safety reputation. I assume, instead, that you're implicitly excluding any non-price information from "market forces" even when people are making decisions based on it, but that's incorrect.

I've read it several times and I think you might be right that it's trying. But if that's the point that it tries to make, then it's simply wrong. I assumed that the comment at the end was a counterbalance.

There's a tipping point for "dangerous airline". 0.5% more dangerous than any of the current airlines wouldn't be noticeably less safe (i.e. 20 vs. 21 crashes for an airline) and if they were competing on costs, the cheaper one would win. And if somehow one airline, despite only a 0.5% difference in safety gap did get branded that way and the rules remained the same, there'd be a market gap in there for a new airline with the same bad standards to come in and fill.

0.5% is 200 vs 201, not 20 vs 21 (that would be 5%).

All an individual cares about is 1 vs 0 crashes-per-flight, not 200 vs 201 crashes per bajillion flights. So if I could buy a ticket on Qantas (0 fatalities in their entire jet era) or Aeroflot (31 in the last 19 years, including 2 unrelated on the same day from the same airport) for the same trip, I'll clearly take Qantas, even if the Qantas flight is 3x as expensive, as I assume most people would.

But here's where humans don't do math well comes in. Even a tiny difference in actual safety is dramatically over-valued. "No child of mine is going to be subjected to an extra 0.5% risk just to see some big mouse in Florida! I'd sooner drive there than fly THAT airline!" And that is how airlines with a bad reputation for safety end up merging, getting bought, shutting down or simply changing names. And how people who can't rationally make decisions end up driving 800 miles to Disney instead of flying, because the risks of driving are much less visible to them.

Hmm, we're operating with opposite assumptions then. The only reason that I remember that Qantas has had zero crashes is that it was on Rainman when his brother couldn't believe how stubborn he was being. Other than that, I'd honestly be more likely to make a choice based on a $50 difference and if I remember how good the food on a given carrier is and how long the checkin lines are.

This might be less true of those who don't fly often for whom it's a big deal, but I'd guesstimate business travelers care less.

That's because you can make rational judgments about what's important to you, and have a feel for the insignificance of 0.5% delta in accident rate. (IOW, I agree with you, but I don't think that most airline ticket purchasers agree with either of us.)

If you say to Joe Public "this airline is 0.5% more likely to have a crash than the one that's $50 less; which one do you want your family to fly?", I doubt many people can easily say "Oh, the cheaper one is preferable." They may arrive there after some agony, but to instinctively know that an extra 1 in 200 on something that's already 1 in 3 million or so is not economically justified on an EV basis. (You'd have to value your life at $30 billion dollars for there to be an EV equivalence between those two choices.)

Nonetheless, I predict many more people would find ease in deciding to take "the safer, more expensive airline" than would find ease in taking "the less safe, but cheaper airline" for their family travel.

Why don't we just outfit aircraft with a miniature Phalanx system that calculates the trajectory of an incoming bird and the probability of an engine strike and then fires up a Gatling gun to neutralize the threat :)

http://en.wikipedia.org/wiki/Phalanx_CIWS

In all seriousness, I wonder if some kind of laser-based defense system could be used as a last resort.

I'd say it's a ways off considering how many years they've spent trying to shoot down much larger missiles with lasers. A missile moves much faster than a bird, but the small size of a bird is going to make it extremely difficult. There's also the issue of how to deal with a flock of birds. This, of course, is assuming you've figured out how to cost-effectively equip hundreds of passenger jets with lasers and the necessary tracking systems given the space constraints. I understand power is also an issue when shooting down missiles. I'm not sure how significantly this requirement is reduced when shooting down birds.

There's also the issue of using a weapon over heavily populated areas and at low altitude. Shooting down a missile will probably take place at high altitude. It's also possible, or even likely, that it will take place over a sparsely populated area or war zone. It could even be over an ocean. The laser might even be fired upwards. If you're shooting down birds from a plane there's a good chance you're going to be firing a laser outward or downward. What if you miss and start blasting holes through nearby buildings?

Bird strikes tend to be a problem most often during takeoff and landing-- usually at either end of the runway. Planes gain altitude so quickly that it's rarely a problem outside of a couple short windows as the plane is approaching or leaving the runway area. I remember reading about an airport with an especially bad bird problem that had success using dogs to keep birds away from the runways.

I think there is a simple solution to this. It might even be possible to put plants or grass around the runway that birds don't like. What about something with thorns that will be difficult for a bird to perch on? Or maybe something with a particular scent that birds will stay away from?

I suggest using predator birds and (directable) loud noise, either high-pitched or predator birdcalls.

That could be a perfect solution, but given the high relative speeds it's probably not possible. I take it must be pretty difficult to detect even a flock of birds at the the necessary distance.

It could be effective on the ground around the runway where the birds hang out until a plane flies into them.

Yes, it would probably be too costly, require too much energy, and would not effectively neutralize flocks. I wonder if a small cannon wouldn't be acceptable.

This should do wonders for property values near airports. ;)

How about air-to-bird missiles?

You could crowd source the targeting - make it arcade game for passengers. Winners get frequent flyer points.

>International Civil Aviation Organisation regulations say that jet engines must be able to ingest a small bird without problems. But for large birds, the rules say only that the engine must not explode.

This is probably the best passage I've read all week.

Do we need to list all the contingencies when an engine must not explode? Can't that be just a general requirement of engines?

Edit: On second thought, I suppose jet engines are generally in a constant state of exploding. Maybe the rule should be "Upon ingestion of a large bird, keep exploding".

"Interestingly, the Smithsonian Institution's Feather Identification Laboratory has worked out which species causes the most costly birdstrike damage. It's the turkey vulture - the bird that originally inspired the Wright brothers."

Irony strikes again!

Irony is coincidentally the name of the turkey vulture.

If I were any kind of ornithologist, I'd devise a sensory device (human-inaudible sound, most likely) that would frighten the birds away, possible via mimicry of a predator.

Note that this is an excerpt of a comment I made on the news article page.

they do this at JFK all the time

This makes me extremely weary of flying, as you can deter birds on take off through sound deterrents on the ground, but not while in the sky. Birds may have even become conditioned to the sound of our noisy flight, thus not deterring them away from airplanes.

There is a entrepreneurial/engineer solution needed here! They rule out adding grilles due to fuel inefficiency, but what about rigging airplanes with the sound deterrents used on the ground - bird radar triggers these sounds? Just a thought...they'd probably have to be crazy insane loud.

I hope someone creates a solution soon! I dont want to land my next flight in the Hudson (chances are slim but still)!

Talk about misplacing your fears.. Airplanes typically cruise at around 33,000 feet; there are no birds that high. All bird-related accidents happen upon take-off and landing, but even then they are barely a threat. The numbers I heard, in the last twenty years or so, there have been about two hundred deaths world-wide due to birds colliding with airplanes and I'm not sure what percentage of that is for commercial airliners versus general aviation. Birds hitting airplanes is probably the least-likely way you can perish.

I'll even bet $5,000 of my own money that neither you, nor anyone you personally know will be killed by a bird colliding with an aircraft, ever.

I'll take that bet, please.

I don't know much about the engineering stuff behind this, but if fuel inefficiency is the only real reason they don't want to add grills, then why not have a mechanical system that removes the grill after they pass a particular altitude (where flocks of birds don't exist) and then add the grill again for landing?

I recall very, very old news footage of raptor eye like structures being attached to jet engines.

I guess those didn't work.

What about doing a good job of keeping the airports and areas around them free or large flocks?

How much would it cost to have trained hawks patrol the area.

NY already has wild raptors living in the city.

I don't think the problem are flocks of large geese living in the area, it's them migrating through. Hawks probably couldn't solve that problem, and if you have any ideas as to how to keep Canada Geese away, you should consider doing it as a startup. They're a common pest in my area of the country.

That's actually a good idea.

I bet even migrating flocks would scatter if a raptor buzzes them.

So perhaps I should get into falconry and charge airports to have my falcon fly through any migrating flocks.

It would be almost like being a super villain.

I don't know. They might just keep flying. What does a flock do when a predator comes and snags one?

Also, if they're in a flock you can probably avoid them more easily than if they scatter.

Keeping raptors around permanently would be problematic. For one, they're probably just as rough on an engine. And for another, how do you feed them for the other 11 months of the year? And do they even eat birds that big?

How about fireworks?

A firework gun that can set at what altitude the fireworks go off and then launch them.

I know of some folks in NYC who do this for a living - they use trained dogs to scare flocks of geese away from parks, courtyards, etc. Mostly for "aesthetic" reasons (read: geese poop a lot). I'm not sure how long the geese stay away after, though. In any event, it's full time work and they get to play with dogs all day. Not bad, eh?

Big money there, definitely. They're a common pest in every area I've been in Canada.

Logan has a staff of people with shotguns to scare away flocks/birds. All bird sightings are reported to the tower and to pilots of incoming aircraft.

At the CPH airport they shoot more than a thousand birds a year.

If there was a hawk, could you be sure that it would stay out of the way of the aircraft? The hawk itself would be a risk of bird strike.

Sure, but a hit from single bird is supposed to be survivable. A hit from a flock of birds isn't.

You could train crows to mob the geese.

The US and Israelis are working on lasers to take out mortars. They are radar based, which would make hitting birds harder. But a vision system tied to the lasers could probably drop a bird before it gets sucked into the turbines.

I thought the a380 has flexible engine blades that bend temporarily upon a bird strike. I wonder if its engines would have shut down with a similar bird strike as the one that occurred yesterday.

Cool, I was wondering that exact thing yesterday: why no jet engine grill? Not all engineering problems are solvable! (Or should be solved.)

I wonder if anyone has looked at doing a cone-shaped grill that extends forward some distance beyond the front of the engine. It would look goofy as hell, but it would only have to be strong enough to survive a glancing impact, rather than a direct hit like a flat grill. Air resistance might be an issue though...

I was just thinking about that same thing.

I think that sort of geometry would encourage the air to flow around the engine, reducing pressure & density of the air actually propelling the aircraft. This would seriously impact the efficiency of the engines, and I suspect this is what the article is referring to. A flat grille would be crazy as it would just collect the birds, held in place by the extreme pressure conditions.

Are we playing 20 questions or something? Just come out with it; the name you are looking for is cow catcher.

Aerodynamics and weight. Both are very important for all aerospace vehicles. Something like that would also decrease engine efficiency.

Supersonic aircraft engines usually have an aerospike, which could impale a bird... that would be a bloody sight.

Reply on news.ycombinator.com