# Is it possible that meteor could strike a commercial airliner?

Is it possible? Are there some such accidents in human history? Is there any rules or systems design to protect airplanes?

• Interesting followup question: did a meteor ever hit a comet? – Jörg W Mittag Nov 2 '15 at 14:48
• of course it's possible. why would it not be possible? perhaps you should revise your question title to reflect the other questions you've asked. – Apologize and reinstate Monica Nov 2 '15 at 22:42
• Is it possible to win the lottery, get struck by lightning, and attacked by a shark on the same day? Is it possible to discover the cure for Alzheimer's, US immigration policy, and the Isreali/Palestinian conflict at the same time? – Nick T Nov 2 '15 at 22:43
• No, that's impossible. There is a special, meteorite-proof force field around all aircraft that prevents them from being struck by extraterrestrial objects. – Tyler Durden Nov 3 '15 at 2:08
• Earth has many cows, and they spend a long time outside; and yet, there are only two documented cases of cows being hit by meteorites, one in 1972 (cow dead and charred), and another in 1938 (minor injures). – Davidmh Nov 3 '15 at 17:29

A meteorite could hit an airplane, sure. There's no known cases of it happening because meteorites which survive atmospheric entry are very rare, and airplanes are pretty small so the likelihood of it happening is extremely low.

• @kharandziuk Meteorites usually fall under VFR, so they are see and avoid. What rules or systems do you have in mind? – SentryRaven Nov 2 '15 at 14:36
• Since we are talking about infinitesimally small probabilities, we should also be infinitesimally anal, I think :-D So, no, it is not possible for a meteorite to hit an airplane, unless the airplane is buried underground, because a meteorite only becomes a meteorite after hitting the ground. Before that, it is first a meteoroid, then when it enters the atmosphere, it becomes a meteor. – Jörg W Mittag Nov 2 '15 at 14:45
• Thousands of tonnes of meteorites hit the Earth every year. We may think it's densely populated, but the chances of a meteorite hitting a populated area are tiny and even if it did, would anyone notice? The chances of hitting an aircraft are so small as to be completely ignored. – Simon Nov 2 '15 at 15:01
• @MontyHarder Would it still be a meteor or become a meteorite if it struck and lodged itself in a flying airplane? – IllusiveBrian Nov 2 '15 at 19:15
• Meteorites which survive re-entry are especially rare when compared to meteorites which survive initial entry. – Lightness Races with Monica Nov 3 '15 at 0:50

Yes, it is possible, however unlikely!

The final report into the downing of MH17 investigated the possibility that the aeroplane was hit by "meteor or space debris"

In section 3.5 a number of scenarios are analysed that relate to the possible source or sources of the object that perforated the aeroplane. These include meteor and space debris.

It was concluded that

The chance of a meteor striking an aeroplane was calculated as being one event in 59,000 to 77,000 years. This value was obtained from the University of Pittsburgh's Department of Geology and Planetary Science and was originally part of the NTSB's investigation into the 1996 accident to TWA flight 800 (see NTSB Report AAR-00/03, dated 23 August 2000)

• one event in 59,000 to 77,000 years - and the odds of it bringing down an aircraft even if "perforated" - 1,000 to 1 or something equally small. So chances of being hit by a meteor bringing down an aircraft, in the hundreds of thousdands of years. Most meteors are the size of grains of sand or very small pebbles. – Simon Nov 2 '15 at 16:15
• @Simon I guess the chance would be comparable to dropping a ball bearing from a 747 and hitting, say, an egg sandwich (Douglas Adams) – Sanchises Nov 2 '15 at 17:14
• Big Sky wins again. – voretaq7 Nov 2 '15 at 17:34
• @sanchises surely such an event would be Infinitely Improbable? – MikeTheLiar Nov 2 '15 at 19:50
• @mikeTheLiar merely virtually impossible... – Sanchises Nov 2 '15 at 20:33

When I served at a military airport in Hungary I read a written report of a MIG-21, supposedly hit by meteor or space debris, crashing the cabin canopy. It was flying with afterburner at high altitude and the pilot's hand was on the throttle lever waiting for instructions. This is why he could manage to slow down and survive. Not an airliner though.

Assumptions.

• 75% of flights are made during daylight hours.
• 75% of meteors occur at night for any given location and those meteorites are equally likely over half the worlds surface (probably about 25% overestimate).
• Aircraft distribution is uniform across the Earths surface (this will make my esimate incorrect by orders of magnitude since they are not, they are far more densely packed over the US, Europe and SE Asia)
• Number of aircraft in the air during the time when the 75% of meteors occur, 2,500.
• Average speed of meteorites, 80,000 mph.
• Average surface area of aircraft, 300 m².
• If a meteor hasn't burnt out by 7 miles, it's not going to (it's a meteorite).
• 350 meteorites per day.

Ignoring the height for now.

Total surface area of aircraft flying when the 75% of meteors fall. 750,000m².

% of Earth surface where the 75% fall covered with aircraft. 0.000003%.

Chance of any meteorite hitting the target surface area (an aircraft). 0.00105%.

Now factoring in height.

• Depth of atmosphere where aircraft are found. 7 miles.
• An aircraft presents a target 150 feet high - big overestimate to account for the time the nose of the aircraft to the tail passes through the track of the meteorite.

• Ignoring that the meteorite will slow down as it passes through the atmosphere.

Assuming a meteorite will pass where the aircraft will be, it spends 0.0036% of the time it falls at the height of the aircraft.

Multipyling the chance of it hitting the area described by the aircraft by the chance of it being at the same height in that area - 0.000000378% or about 4e-7.

Many people struggle to understand numbers that small. To put it into perspective, the accepted chance of you being struck by lightning in your lifetime is 8e-5, or about 200 times as likely as an aircraft being hit by a meteorite.

This is so tiny that any one of my assumptions being wrong will make the number meaningless.

Safe to say, possible, but so unlikely as to be not even worth considering.

• "75% of meteors occur at night" - sorry, that raised a couple of warning flags for me. What? Why? What have meteorites to do whether there is night or day? Do you have a credible source? Isn't just that meteorites are more visible during the night? – vsz Nov 3 '15 at 22:14
• @vsz Most meteors occur because the Earth passes through a cloud of particles. Therefore, most come from the direction the Earth is passing through space. You could start here for more information. – Simon Nov 3 '15 at 22:20
• @reirab Because 350 meteorites fall during the time 2500 aircraft are airborne? – Simon Nov 3 '15 at 22:41
• Thanks for doing a full answer and covering the 3D dimension. – Schwern Nov 3 '15 at 23:46
• @mins Agreed. Edited. – Simon Nov 4 '15 at 7:10

Possible, but unlikely. There are no documented instances of a meteorite striking an airplane.

Most of the meteoroids that become meteors are of the size of a grain of sand, and will burn up by the time they reach the cruising altitude of the commercial airliner.

A hundred or so meteors of the size required for impact at high altitudes strike earth every hour. At the terminal velocity of the meteors, the aircraft is practically stationary and the probability of a meteor striking an aircraft is simply the ratio of the total area of aircraft in air to the total surface area of earth.

Around 4000 aircraft are in skies at any given time- each with a projected area of ~300 $m^{2}$ (if we are being generous). This means that the probability of an aircraft getting hit by a meteor is ~$2 \times 10^{-9}$ at any point of time.

Assuming that each aircraft makes a 8 hour flight (again, being generous), the probability of that getting hit by a meteor is ~$10^{-6}$.

So, basically the probability of an aircraft getting hit by a meteor is pretty small; Again, if we continue to operate aircraft at the rate we do, one of them will certainly get hit by a meteor.

• Your logic is flawed. Most meteroids enter the atmopshere from more or less the same direction, that is to say from the direction in which the earth is travelling. That's why meteor showers appear to radiate from the same point in space and named after whatever arbitrarily named object they appear to emenate from. one of them will certainly get hit by a meteor. This is also flawed. Even if it hasn't happened, then it is not "certain" that it will and it may well have already happened. Probablilities know nothing of history. If it happened 1 second ago, the probability remains the same. – Simon Nov 2 '15 at 18:30
• Because the Earth does not travel towards the sun, most meteors occur at night when air traffic is a lot less. You also assume that aircraft are evenly distributed but they are not. They are concentrated in a few areas of the world during the day. You would need to build a much more complex model to begin to guess at a probability but it's a lot lower than you suggest. It may already have happened when some puzzled engineer could not figure out what that hole in the horizontal stabiliser was and just fixed it up with no report to file. – Simon Nov 2 '15 at 21:12
• The answer is a good back-of-the-envelope calculation to get the order of magnitude and demonstrate just how wildly unlikely it is. It's basically the Big sky theory. The probability is likely a lot lower because the calculation should be done for three dimensions (plus time), not two. The distribution of aircraft in the sky does not matter if we assume meteor paths are random (ie. that they have no preference for high density air travel lanes). – Schwern Nov 3 '15 at 0:14
• Umm.. The "front" of the Earth is the dawn terminator. So a meteor approaching from the front has a 50:50 chance of hitting Earth on the day-time or night-time. You might get a factor of 2 into the equation but the Answer's logic is far from flawed. What is flawed is your comment about probability - the question is not whether the probability in a particular instant increases with time; it is whether the probability of an event happening at all increases with time. This is certainly the case. – Oscar Bravo Nov 3 '15 at 13:17
• @OwenBoyle Nope. Most meteors occur after midnight for any given location. One of many explanations why - www2.le.ac.uk/departments/physics/research/xroa/… – Simon Nov 3 '15 at 20:10

It could happen. This lucky skydiver was only meters from a falling space rock, and got it on tape.

Had he been an airplane (or a few meters longer) he would have been hit!

• Except it's not - news.discovery.com/adventure/extreme-sports/… – Simon Nov 3 '15 at 19:53
• While the scientist involved thinks it's a true story, other scientists are more skeptical. Note that, technically, based on the scientist declaration about the origin, it's an asteroid from the asteroid belt, not a meteor (comet debris). – mins Nov 3 '15 at 19:55

This is, sadly, a highly topical question. There have been more than a few aircraft downings where a meteor impact has at least been considered so I think it is worth exploring.

Acknowledgment: In the following calculations have gratefully borrowed figures from various contributors above.

First, let's consider the question about traffic patterns:

• Meteors mainly come from the direction Earth is travelling through space as it orbits the sun (effectively, the Earth "runs them down").
• Meteors are in orbit around the sun before they hit Earth. So they are just as likely to come from inside the Earth's orbit (on the way out from the Sun) as from outside the Earth's orbit.
• This means they mostly occur between midnight and noon the next day. From noon to midnight, you're on the "rear end" of the Earth.
• I'm assuming traffic density between midnight and noon is roughly the same as between noon and midnight. This cancels out any effect of diurnal variation in traffic patterns. If you disagree with this point, divide the answer by two or three.

Second, I am going to integrate over a 24hr period to cancel out the variation in aircraft density as the "front" of the Earth moves round the planet (there are going to be more targets when Europe, North America and SE Asia are at the front than when it's dawn over the central Pacific Ocean).

Third, the aircraft speed is irrelevant. If a beetle is on a dartboard and you randomly throw a dart, it doesn't matter if the beetle stays still or runs about.

Now to the sums: To be clear, I'm trying to work out the probability of any meteor hitting any aircraft in a 24 hour period. This is simply the area of the target divided by the total area presented by the Earth to the oncoming meteor.

So: 10,000 planes in the air divided by 2 (only the leading half of the Earth is in target) $\times$ 300$m^2$ per plane divided by $\pi r^2$ for $r=6371km$ gives $1.2 \times 10^{-8}$. So one in a hundred million, roughly.

Now, how many meteors that could down a plane, hit the Earth per day? Planes are pretty fragile - I'm going to guess that a 0.2m bolide (bowling ball?) if it hit the plane anywhere, would definitely do it. One reference above says there are about 2000 of these per year. So 5 per day.

That gives a final probability that any plane is downed by any meteor in any 24 hour period of $6 \times 10^{-8}$.

So the rate is about once every 40,000 years, or so. Yeah... probably not worth bothering about.

• You're not that far away with your "back of the envelope" than a whole bunch of experts (see my answer) – Jamiec Nov 5 '15 at 15:15
• Believe it or not, I only read the numbers in the yellow quote-box after I'd finished this calculation. Another way of putting it is that there's about a 1000:1 chance of it ever happening anywhere in the next 50 years. – Oscar Bravo Nov 6 '15 at 7:40

I see that someone else did the math on the probability already, but I wanted to give some math with dimensions and numbers that might be more accurate, as well as give a comparison to other causes of plane crashes.

At any point in time, there are about 10,000 commercial aircraft in the air, according to flight radar's metrics (although I'm not too sure how accurate those are). Assuming an average length of 50 meters, and a wingspan of 50 meters, and a hull and wing width of 8 meters, that's 800 m² per flying aircraft, and 8,000,000 m² for all planes combined, or about 8 km².

In a comment, someone pointed out that aircraft dimensions are actually closer to 200 m². The reason I chose math of 800 m² is because a direct impact is not the only way a meteor could affect an airborne craft. A sufficiently big meteor leaves behind a heat trail and a smoke trail. The heat trail causes local airflows to change, which could cause turbulence onboard passing aircraft. The smoke trail could theoretically damage the engines similar to how volcanic ash does, given that they're both ash and dust. If a layman is on an airplane affected by one of these incidents, it's understandable that they view this as "being hit by a meteor".

How big is 8 km²? Well, that is comparable to the size of Greenbelt park in Staten Island, and about 2/3 the size of the Royal Borough of Kensington and Chelsea in London. I've tried finding reports of meteorites being found in that area, and while it is not impossible that one has landed there without anyone noticing, it is a very rare event. In fact, while there hasn't yet been a report of a plane crashing by a meteorite, a passenger killing both the captain and the copilot has been reported at least twice as the reason of a crash. I would personally be more worried about a mid-air impact of another plane, given that has happened enough by now to be featured multiple times on Mayday! (Air Crash Investigation).

If you only count direct impacts as actually hitting your aircraft, then assuming an average surface of 200 m² for a plane, and meteors only coming directly from above (since they can also come from the front, the sides or the back), there is a total surface size of about 2 km² when all aircraft are counted. This is a little smaller than the City of London (not the entirety of London, but the original inner city), or just over half the size of Central Park in New York.

• The OP didn't said this is something frequent. Only asking if this could be possible. As for your claim that meteorite impacts are rare... have a look at the Antarctic Meteorite Program: "Of the almost 16,000 Antarctic meteorites collected since 1976, over 14,000 have been permanently transferred to the Smithsonian." Only the ones collected! – mins Nov 3 '15 at 20:25
• @mins Note that the actual meteorites are much older than 1976; the conditions in Antarctica are such that a meteorite can sit undisturbed in the snow for thousands of years. – duskwuff -inactive- Nov 3 '15 at 20:29
• @duskwuff. It sometimes snows, also in Antarctica (about 15 cm per year), but agreed. The (estimated indeed) actual mass of meteorites is about 50.000 tons each year. Discarding very small particles: "Over the whole surface area of Earth, [...] 18,000 to 84,000 meteorites bigger than 10 grams per year". – mins Nov 3 '15 at 20:43
• @mins Antarctica has been an icy shelf for over 15 million years. About 5500 meteors hit Antarctica every year on average according to jdetrick.blogspot.be/2013/12/… and doing some math on that. That includes those that burn up in the atmosphere. Antarctica is about 1/36 of the Earth surface, so by your math, 500-2500 meteorites should hit it every year. Over a period of a thousand years, that's about 500K-2.5M meteorites. I didn't say they were rare, I said they were rare if we're talking about an 8 km² area. – Nzall Nov 3 '15 at 20:47
• Ok Nate, I agree with you. – mins Nov 3 '15 at 21:03