Professional investigator concludes - "what's the fuss about?"

[Brojon]

Great article in Forbes where FINALLY someone has exercised common sense backed up with professional credibility. His conclusion is a hobby drone represents little to no danger to commercial aircraft.

A Small Drone Hits A Commercial Airliner...And Nothing Happens

 

[gnirtS]

Brilliant. A sample size of 1 on a relatively slow moving prop plane. How exactly can you extrapolate anything from that?!

I know someone that got hit by a car. They were completely unhurt. Therefore cars cant hurt people. Same problem.

There simply isn't data and aren't any properly audited, reviewed papers to draw any sort of conclusion either way.

 

[Brojon]

Did you miss the part where this guy is an experienced aviation accident inspector?
As far as properly audited and reviewed papers - you're ignoring the mounds of data where they test aircraft for impact damage using items substantially harder and larger than hobbyist drones.
Quick - would you rather have a Mavic fall on you or a frozen turkey?

 

[gnirtS]

Did you miss the bit about a sample size of 1? I assume you did.

Also, you're ignoring mounds of data from last years UK tests that DID have problems caused (albeit with questionable methodology). Here it is, i'll provide a direct link so you find it harder to ignore:- Drones and manned aircraft collisions: test results - GOV.UK

You also clearly have no understanding of the "turkey test". You fire a turkey at a plane and guess what - something happens. Things break. All that test is designed for is to prove there won't be catastrophic damage. It still needs expensive repairs.

Try this for an experiment, go outside and hurl some small rocks at passing cars. What you'll find is none will explode into pieces. What might surprise you is those rocks do some minor damage, annoy the drivers and cost money to repair. So something happens.
Now go outside and throw your mavic pro at a car doing say 60mph, you'll find the same thing happens as with the small rocks, in other words, something happens.

Only a dribbling moron is going to think a consumer drone is going to down or destroy a plane. It simply wont happen. But downing a plane isn't the issue. It costs a lot of money to ground and even inspect a plane after any suspected impact of anything at all. A drone is more than capable of that.

 

[Former Member]

Only a dribbling moron is going to think a consumer drone is going to down or destroy a plane.

You will then have to categorize the consensus of the general public and the US FAA as "dribbling morons."

 

[lisadoc]

Quick - would you rather have a Mavic fall on you or a frozen turkey?

They don't test aircraft against frozen turkeys. That would be incredibly dumb (hence the urban legend about the engineers making that silly mistake).

 

[Brojon]

Clearly you're spoiling for a fight. I'm well versed in statistics and fully well know that you can in fact make some rational calls from limited data. Fer instance;
Would you acknowledge that in a study with a sample size of one, swatting a fly with a 2x4 will pretty much have the same effect no matter how many times you do it? I would submit that you could also analyze the reverse and pretty much conclude the board would sustain minor if any damage from the act of swatting. Some things are fully capable of being analyzed reducto ad absurdum. I would submit the relative size and materials of the fly vs 2x4 are analogous to the drone and aircraft.
We're not going to quibble about the paint getting scratched - the entire hysteria around drones and aircraft is the fear of catastrophic damage. It just isn't likely. In fact the odds are *much* better that a person or house on the ground will get damaged by falling chunks of frozen waste from said commercial aircraft.
There have been limited studies and simulations on drone strikes. Unsurprisingly they found large aircraft relatively immune but helicopters and small craft at a much larger risk. Of course these small craft are also much more at risk from birds and flocks of birds. I would submit you're much more likely - statistically speaking - of a bird strike than a drone given the population densities.
Frozen 'poo bomb' smashes hole in couple's roof after being flushed from jet

Anyway - that's all I'm going to say about it since you're mind is made up.

 

[Brojon]

You will then have to categorize the consensus of the general public and the US FAA as "dribbling morons."

LOL - you would seriously invoke the credibility of John Q. Public and a government agency already rebuked for bureaucratic over reach?

 

[Brojon]

They don't test aircraft against frozen turkeys. That would be incredibly dumb (hence the urban legend about the engineers making that silly mistake).

Read carefully - I didn't say that at all.

 

[lisadoc]

But downing a plane isn't the issue. It costs a lot of money to ground and even inspect a plane after any suspected impact of anything at all.

That's simply not true. Every day, birds impact dozens/hundreds of aircraft operating around the globe (depending on the time of year). 93% of those impacts are completely inconsequential, resulting in a brief look at the aircraft, and wiping the remains away from the plane (hopefully keeping them and reporting it to the FAA/ICAO), if that.

Aircraft are only grounded if the bird strike results in actual damage or is ingested into the engine and it must be boroscoped. Less than 7% of all strikes result in a negative effect on the flight in any manner (in the US). That percentage is even less outside the US, and is also growing smaller over the years (in the US and the world) as airplanes become more "resistant" to strikes and airlines replace their aging fleet of aircraft. Moreover, many of the strikes resulting in a "negative effect on flight" are the result of strikes with birds or flocks of birds/wildlife weighing more than 5 lbs. (far more than a Mavic at 1.62 lbs).

Depending on a number of factors, but mostly the location of the strike on the aircraft and the speed of the plane (E=1/2*m*v*v), a Mavic would likely cause no problem to a commercial airliner. Ingestion into the engine is a completely different thing, but even then, modern aircraft engines are certified to ingest 4 lb birds and continue operating to be shut down safely (8 lbs in newer aircraft). So it is very unlikely that a strike with a Mavic or a Phantom will ever bring down a plane.

Is it something that should be avoided/prevented? Absolutely. Is it something to panic about and blindly react due to fear of the unknown? No.

 

[sar104]

Great article in Forbes where FINALLY someone has exercised common sense backed up with professional credibility. His conclusion is a hobby drone represents little to no danger to commercial aircraft.

A Small Drone Hits A Commercial Airliner...And Nothing Happens

Well that was a wasted 5 minutes. I mistakenly had expectations of some kind of statistical analysis, backed up with results from actual impacts of aircraft with comparable objects. Instead it turned out to be about as reasoned and rigorous as the average post on the subject on this forum. To summarize his "professional opinion", "I don't believe reports of drone/aircraft collisions although here's one that did happen and caused little damage", plus "drones can't seriously damage aircraft engines or other components". Not a single reference to any actual study or data. Forbes was scraping the barrel there.

 

[sar104]

That's simply not true. Every day, birds impact dozens/hundreds of aircraft operating around the globe (depending on the time of year). 93% of those impacts are completely inconsequential, resulting in a brief look at the aircraft, and wiping the remains away from the plane (hopefully keeping them and reporting it to the FAA/ICAO), if that.

Aircraft are only grounded if the bird strike results in actual damage or is ingested into the engine and must be boroscoped. Less than 7% of all strikes result in a negative effect on the flight in any manner (in the US). That percentage is even less outside the US, and is also growing smaller over the years (in the US and the world) as airplanes become more "resistant" to strikes and airlines replace their aging fleet of aircraft. Moreover, many of the strikes resulting in a "negative effect on flight" are the result of strikes with birds or flocks of birds/wildlife weighing more than 5 lbs. (far more than a Mavic at 1.62 lbs).

Depending on a number of factors, but mostly the location of the strike on the aircraft and the speed of the plane (E=1/2*m*v*v), a Mavic would likely cause no problem to a commercial airliner. Ingestion into the engine is a completely different thing, but even then, modern aircraft engines are certified to ingest 4 lb birds and continue operating to be shut down safely. So it is very unlikely that a strike with a Mavic or a Phantom will ever bring down a plane.

Is it something that should be avoided/prevented? Absolutely. Is it something to panic about and blindly react due to fear of the unknown? No.

Impact speed is certainly a factor, but by no means the only important factor. Birds are soft (except when frozen, which is a significant observation as well as an amusing anecdote). The force exerted during an impact is a very strong function of the mechanical properties of the objects involved. Soft objects deform more during the initial stages of the impact, and so the rate of change of momentum (force - from Newton's 2nd Law) is lower. Hard objects colliding lead to much higher transient forces.

Structures such as aircraft windshields are designed to be somewhat resistant to bird strikes but are likely to fail catastrophically when hit by a hard plastic/metal composite drone. That's probably the primary hazard to aircraft, although helicopter rotors (especially tail rotors) are also likely to be very vulnerable. Note that there was significant damage to the main rotor of the UH-60 that hit a Phantom over New York recently, and that's a hardened military aircraft. Aircraft turbofans are a complete unknown - again they are not designed around this kind of hazard.

 

[Pathogen]

You will then have to categorize the consensus of the general public and the US FAA as "dribbling morons."

Wait, what?

 

[lisadoc]

Birds are soft (except when frozen, which is a significant observation as well as an amusing anecdote). The force exerted during an impact is a very strong function of the mechanical properties of the objects involved. Soft objects deform more during the initial stages of the impact, and so the rate of change of momentum (force - from Newton's 2nd Law) is lower. Hard objects colliding lead to much higher transient forces.

I agree with everything you said. I didn't get into it because the physics alone starts to get complicated and the overall situation is even more complex. It would take pages and pages to even skim the details of this issue so I tried to edit myself and keep it within the limits of this forum (BTW, this very topic is what I do for a living).

I would also argue that not only the physics involved would have a significant effect on the problem, but so would the behavior (and there's about another 1,000 other principles that would have some effect as well). For example, if you asked me whether or not I would prefer to fly into an airport with 500 crows scattered through the infield or one with 20 pigeons (both individual birds being roughly the same), hands down I would go to the one with the crows, since they are far more adept at avoiding collisions with planes and tend not to fly in large compact flocks like pigeons. The same can be said for drones (in general). Unlike birds, where the object is uncontrollable by humans in order to avoid a collision, drones are under the direct control of an operator. Most (and obviously not all) drone operators would likely actively try to avoid colliding with an aircraft, even if they are operating near an airfield. As a result, the likelihood of a drone hitting an aircraft is far lower than if these were randomly flying objects around an airfield. In essence, drones behave much more like crows than they do pigeons.

But again, I would like to make it clear that I'm not advocating flying your Mavic near operational aircraft. The risks involved are real, for the drone operator as well as the aircraft occupants. I'm simply noting that the reactionary hyperbole attached to the usage of small UAS's (by the FAA, government officials, and the general public/media) are far from the reality of the situation and deserve a rational risk management perspective.

 

[sar104]

I agree with everything you said. I didn't get into it because the physics alone starts to get complicated and the overall situation is even more complex. It would take pages and pages to even skim the details of this issue so I tried to edit myself and keep it within the limits of this forum (BTW, this very topic is what I do for a living).

I would also argue that not only the physics involved would have a significant effect on the problem, but so would the behavior (and there's about another 1,000 other principles that would have some effect as well). For example, if you asked me whether or not I would prefer to fly into an airport with 500 crows scattered through the infield or 20 pigeons (both birds being roughly the same), hands down I would go to the one with the crows, since they are far more adept at avoiding collisions with planes. The same can be said for drones (in general). Unlike birds, where the object is uncontrollable by humans in order to avoid a collision, drones are under the direct control of an operator. Most (and obviously not all) drone operator would likely actively try to avoid colliding with an aircraft, even if they are operating near an airfield. As a result, the likelihood of a drone hitting an aircraft is far lower than if these were randomly flying objects around an airfield. In essence, drones behave much more like crows than they do pigeons.

But again, I would like to make it clear that I'm not advocating flying your Mavic near operational aircraft. The risks involved are real, for the drone operator as well as the aircraft occupants. I'm simply noting that the reactionary hyperbole attached to the usage of small UAS's (by both the FAA, government officials, and the general public/media) are far from the reality of the situation and deserve some rational risk management perspective.

That's a very reasonable analysis. You do terminal ballistics for a living, or physics in general?

 

[lisadoc]

That's a very reasonable analysis. You do terminal ballistics for a living, or physics in general?

Aviation safety.

 

[Brojon]

About that reimbursement on wasted time...

 

[sar104]

Aviation safety.

I see. Then you should post more often on the subject. I'd certainly be interested.

 

[danman999]

Did you miss the part where this guy is an experienced aviation accident inspector?
As far as properly audited and reviewed papers - you're ignoring the mounds of data where they test aircraft for impact damage using items substantially harder and larger than hobbyist drones.
Quick - would you rather have a Mavic fall on you or a frozen turkey?

A frozen turkey does not have metal parts. One errant screw, nut or bolt in a turbine engine can be catastrophic.
The anodized aluminum props on many smaller airplanes (including many turboprops) could easily be bent, throwing the prop off-balance, necessitating a shutdown of the engine.
A pitot tube and/or static port could be damaged, resulting in the loss of indicated airspeed and/or altitude and vertical speed.
I could go on, and on.
I am a FAA certificated airplane pilot, instrument and instructor rated. I also worked in aerospace for decades as a MSC to many projects including the Boeing 777.
Anybody who says drones pose no threat to airborne aircraft are simply full of it.

 

[Marko9219]

The single, biggest, most dangerous, and very, very real threat these drones present to aviation is the possibility of ingestion by a jet engine, resulting in catastrophic failure of the engine, resulting in possible aircraft loss. This is especially serious if it happens at low altitude during take-off, which is PRECISELY when there is a high probability of it happening. All the arguments about impact damage to the hull/windshield/wings aside, the compressor blade damage to a modern jet engine could be fatal to the aircraft and its crew/passengers.