Bird Strikes

By | May 11, 2017

Author: Ting Lei 

1. Introduction

The event of an airborne animal hitting an airplane in flight is referred as bird strike. Although bird strikes are a lesser hazard to aviation than some other well-known hazards such as air turbulence and icing, it still poses a sizable threat to airline safety and do present risk that needs to be addressed. According to Bird Strike Committee USA, wildlife strikes cause over $650 million annually in damage to U.S. civil and military aviation.

The goal of this article is to discuss some of the characteristics of bird strikes, raise the awareness of this issue, and help reduce the likelihood of bird strikes.

2. Analysis

2.1. Software Used

I used Excel to preprocess the dataset and Tableau 10.1 to visualize the data.

2.2. Dataset

The data is acquired from Federal Aviation Administration website. It contains a total of 140,537 bird strike records in United States from the year of 2000 to the end of 2015. The dataset documents each incident of bird strike in terms of date, damage to aircraft, cost to repair, bird species, location, types of Airline, etc., with a total of 94 fields.

2.3. Approaches

According to the U.S. Department of Agriculture, many populations of wildlife species have grown significantly in the last 10 – 20 years and adapted to living in urban environments, including airports. Such explosion in wildlife population has led to the increase in bird strikes as show in the Figure 1 below. The number of strikes reported annually doubled from 6,561 in 2004 to 13,692 in 2014. The number of bird strike records will continue to grow as there is almost a linear increase in the number of incidents in the last decade.

Figure 1: Bird Strike Trends

Along with those wildlife that live in the United States, there are also between 500 million to 1 billion birds that migrate over United States each year. And this could explain the fact that although bird strikes happen any time of the year, the prime months for bird strikes falls between July to October, which is the typical migratory season. The figure 2 below depicts the bird strikes in each month, and July to October sum up to 52.2% of the annual total.

Figure 2: Bird Strikes Incidents by Month

Figure 3 describes the number of bird strikes occurred during different phases of flight and time of day, where “phase of flight” is a set of term to categorize the operational phase during the aircraft accident. It is not surprising to see that majority of bird strikes occurring during the day since most flights are in the daytime. However, birds do fly a lot at night which makes the night the second highest time for bird strikes.

Figure 3: Flight Phase at Strikes

Figure 4 describes the height of the aircraft when bird strikes occur. As show in both figure 3 and 4, bird strikes usually occur when an aircraft is flying at low attitudes. Hence, the most common conditions for a bird strike are during approaching, landing, or taking-off with the altitude within 100 feet above ground level. This could be explained by the fact that most bird species fly at a low attitude; however, there is also a great number of bird strikes from 900 feet to 4000 feet above ground level as shown in the Figure 4 below.

Figure 4: Bird Strikes at different Height

While bird strikes most likely to damage the wings and the engines, all areas of an aircraft can be damage as shown in the Table 1 below. A hit in windshield may result in the cracking of the surface of windshield and may possibly disrupt the air pressure inside the cabin. Meanwhile, when wildlife get caught inside the engine, it can possibly cause a disruption in the rotatory motion of the fan blades and result in the failure of the engine.

We must also keep in mind that many bird species are capable of inflicting damage to aircrafts. Between 2000 and 2015, there are over 694 species of birds that were involved in strikes. Although the Mourning Doves are the most found species with 7,025 records in Bird Strikes, with only 2% chance of causing damages, the Mourning Doves had not been listed as the most hazardous bird species to flight (only 135 damaged records). The figure 5 below identified a list of birds that are most hazardous to flight: Gulls (521), Canada goose (496), White-tailed deer (442), Red-tailed hawk (284), Turkey vulture (275). In general, any size of birds is problematic and have the possibility to result in accidents.

Figure 5: Bird Strikes by Species

Lastly, among the nation’s 30 busiest airports, the five facilities with the top strikes rates from 2000 to 2015 were the Denver Intl. Airport (5,256 strikes), Dallas Intl. Airport (4,150 strikes), Chicago O’Hare Intl. Airport (3,019 strikes), Memphis Intl. Airport (2,680 strikes), as well as the John F Kennedy Intl. Airport (2,653 strikes). However, the top three airports in terms of damaging strikes were Sacramento Intl. Airport (237 damaging incidents), Salt Lake City Intl Airport (170 damaging incidents), and Orlando Intl Airport ( 153 damaging incidents).

Figure 6: Most Affected Airports

3. Conclusion

In conclusion, bird strikes usually cause no more than minor damage, but they can still pose a threat to flight operations. Pilots and operators should be knowledgeable that bird strikes occur more often in the late summer/autumn season and are more likely to be during the landing phase of the flight when the aircraft is at a low altitude.

Although there had been reported with over 7,000 bird strikes incidents involving Mourning Doves; however, only 135 of the incidents had been reported with damages. Whereas the Gulls lead to the largest number of reported damages with 521 incidents.

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13 thoughts on “Bird Strikes

  1. Michael Baer

    This is a very interesting study and the data was analyzed and presented very well. Another interesting way this data could have been presented would be to associate a dollar amount representative of the damage cost attributed to that certain category. For example, this could help the readers visualize how much total cost each part of the plane is or how much damage done in the day or night costs relative to other times.

  2. Jesse Parritz

    Very interesting analysis. Regarding the airports with the most birdstrikes, I’d be interested to know what factors related to the airports and their locales impact the number of bird strikes. Of course, the busier airports naturally have more birdstrikes on account of simply having more flights, but that doesn’t explain why Denver has more than O’hare despite O’hare being a much busier airport. Perhaps O’hare has better controls against bird strikes, which would be an interesting follow-up analysis to dive into.

  3. Lizzy Svigelj

    What an interesting study! I had no idea that bird strikes caused so much damage. It is also interesting how bird populations have grown so much even in urban areas.

    I thought your study was well done. One question/comment I have is about how the airports with the most bird strikes did not experience the most damaging bird strikes. Do you have any thoughts as to why that is? Would it be possible to explore a risk adjustment to the data using the types/sizes of birds that live around those different airports? It seems counter-intuitive that the airports with the most strikes would not also experience the most damaging strikes. Thank you for sharing your work!

  4. Ed Olson

    This was interesting to see the sheer volume of bird strikes experienced at airports! Is the white-tailed deer a species of bird or an actual deer? While I am sure they are hit on the tarmac, I can see how they would cause a lot of damage.
    Also Denver, Dallas, & Memphis are cities with a high incidence of bird damage strikes on aircraft. It also seems most strikes occur on approach. It would be interesting to know if the orientation of runways would have something to do with this, as these 3 cities have a number of North – South runways. Chicago & JFK are close to large bodies of water. LA & Atlanta both have large volumes of flights, and both have runways that run mostly West-East. Thanks for sharing.

  5. Thomas Magnuson

    Thank you for your detailed analysis and visualizations. This information was very clearly conveyed – helping the readers acknowledge this growing problem. I am curious if the Federal Aviation Administration has any information regarding the inter arrival time of the records and whether these incidents occur in groups, as I imagine birds often fly in flocks.

  6. Henry Rose

    First of all, I had no idea that bird strikes posed such a significant problem for the aviation industry today. I guess that it makes sense when I step back and think about it, but I didn’t think small animals could cause damage to something like an airplane. Second, I’m really interested in understanding why the number of strikes doubled form 2004 to 2014. Are there more planes in the sky, causing the number of birds striking these planes to increase? Or, is it a combination of things occurring causing the linear increase of bird strikes?
    Thanks for sharing

  7. Olubukola Ogunsola

    The report says bird strike causes $650M damages annually but the conclusion says the damages are minor, I believe $650M annual damage is major except your rating is based on loss of life and other factors.

  8. Sumukh Ramesh

    This analysis is interesting. It would be interesting to take this analysis and look at migration paths for Gulls and Mourning Doves. I’m interested to see if the airports fall in the path of migration patterns that is regularly used by the birds. Such analysis could help city planners in future when they plan to build any major infrastructure.

  9. Erik Pechnick

    This definitely makes me a little more worried to get on my next flight. I was interested to see how much birds can afflect planes. One question I have is if the airports that experience the most damage are also the areas that the birds with high damage rates originate from

  10. Eric Fleming

    I remember hearing a lot about this problem in 2009 after Sully Sullenberger landed a plane on the Hudson River after the plane struck a flock of geese, causing both engines to fail. I remember hearing some pretty crazy numbers back then about how forceful impacting a goose at the speeds airplanes travel at is. I found this article that says that striking a goose in flight causes a force on the plane equivalent to 50,000 pounds. It’s incredible that modern planes are so well engineered that hundreds of these goose strikes happen each year without incident.
    I also found information that said after even a minor bird strike, a plane is required to land at the nearest airport. Then passengers must switch planes and a new crew is assigned. I wonder if the cost of this disruption was included in the cost of bird strikes. Regardless, it’s reassuring to see that the problem is more of money than safety, most of the time.

  11. Ben Pollak

    This is a very interesting study. I wonder if the trend for number of bird strikes over time has to do in part with an increase in flights over time? I’m sure aviation travel is growing in addition to the bird population, so it would be interesting to take that into account in the study. It was also really interesting to see that Denver had significantly more bird strikes than other airports. I wonder if this is in part due to Denver’s altitude? I really liked the visuals and I learned a lot about a new topic. Thanks!

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