Birds and the plane

Are warnings on high bird activity meaningless without standards?

Recently I have been giving quite a few thoughts on standards of "bird activity high", or rather the lack of them. If you have 5 minutes, I would appreciate your feedback.

  1. Do you reduce speed and/or turn on landing lights on approach if you hear “bird activity high” on ATIS?
  2. Would you reduce speed and/or turn on landing lights if the information was based on a standard?
  3. Do you include bird activity in your briefing today?
  4. Would you include this in your briefing if it was based on a standard?

What is the point with these questions, after all?

From time to time pilots are issued warnings about "bird activity high" on ATIS. Ideally, this would prompt a set of actions corresponding to the situation – typically turning on the landing lights, reducing airspeed or a combination of the two.

The question, however, is whether warnings about high bird activity have any real meaning, as long as there is no official standard regulating when airports report “bird activity high.” Even worse, some airports issue warnings per default, thus rendering the information essentially meaningless.

So how could a standard increase the value of these warnings? Do they even matter in the first place? Let us look at the factors at play.

How to reduce risk: Speed is of the essence!

Although bird strikes rarely lead to fatalities, they are the direct cause of significant damage to planes, as well as dents in the profit of airlines.

One of our clients, a major European airline, reports approximately 600-800 bird strikes a year. Each bird strike amounts to an average cost of € 56,000, split almost evenly between costs going towards repairs and indirect costs such as compensation to passengers, re-booking of flights etc.

Therefore, a fair warning leading to an efficient response avoiding a strike or minimizing the potential damage is of the essence.

If there is, in fact, high bird activity in a given area, the operational response to a “bird activity high” could very well be: “Reduce your speed," as a 15% speed reduction reduces the impact energy by approximately 1/3.  As a direct result, the risk to pilots and passengers, as well as related costs of following repairs are reduced significantly.

To understand what the speed means for the impact, I looked at the kinetic energy in the table below:

Table 1 Approximate Bird-impact Forces (lbs.) (1).

On an Airbus 321 cruising at 250 knots, a 15% reduction to minimum clean speed 210 knots could have a significant effect. When looking at FAR 25 design criteria and impact speed, it becomes evident that a mere 15% reduction in speed, could bring you within the design criteria – even in case of a collision with an avian heavyweight like a Canada goose.

Table 2 Summary of FAA Airframe Bird Strike Airworthiness Requirements (Detailed information in Appendix 5.1)(table 5.5 in the source) (1).

These points are essential to keep in mind, considering the risk in case of a bird strike on engines or, especially, the windscreen.

Not only are these areas among most critical, but also where the majority of bird strikes actually happen. This should be clear from the illustration below, showing the locations and percentages of impacts, based on statistics from pilot and maintenance reports:

Picture 1 Locations of bird strike damage (4).

Where is the risk?

The risk of bird strikes increases with proximity to the ground. Most of the time a speed reduction will be possible. The consideration here is, that a speed reduction would also lead to a slightly prolonged airborne time. However, we are talking about 1-2 minutes of the flight, and only when a trustworthy high bird activity message is given.

Picture 2 The risk of bird strikes increases with proximity to the ground (3).

The data is already being collected – let’s use it!

Most airports have bird control staff that are already recording the bird activity, and are taking action to remove the birds from the aircraft operation area. That means that the data is already there, now we “just” need to apply it by agreeing on a definition of high bird activity.

A note here could be, that the bird activity data will be generated based on what is happening in the airport operations area, not in the surrounding areas where the aircrafts are approaching/departing. It is, however, the only data source we have in most airports.

It is fairly simple to formulate a basic equation, that could work as a basis for determining when to issue a high bird activity warning. For example:

Picture 3 Formula for determining when to issue a high bird activity warning.

The calculation could also be based on the risk level of the recorded birds (in the airport’s risk matrix), although that would require all airports to use the same risk matrix in order for the information to be standardized.

General operational response

When looking at the operational response to a “bird activity high” statement, we see following possibilities (2):


  • Reduce speed;
  • Turn on landing lights;
  • Include in briefing;


  • Low thrust settings;
  • No go-arounds – fly through and land;
  • If a strike occurs – do not use reverse thrust;


  • Include in briefing;
  • Turn on landing lights;
  • If birds are present – request them to be removed.


Thank you for taking the time to read the article. I look forward to receiving your feedback on this topic by sending me your thoughts at [email protected]


Written by Peter Hemmingsen (CEO, AscendXYZ)



1: Transport Canada, Bird impact force:
3: FAA/USDA wildlife strike report:
4: Boing: Strategies for prevention of bird :



Aalborg Airport

Bird Strikes down by 50% in Aalborg Airport

Written by Thomas Hugo Møller (Quality and Compliance manager at Aalborg airport).

By using data to understand wildlife behaviour and implementing new active measures, Aalborg Airport (Denmark) has reduced bird strikes by one half in one year.

Aalborg Airport is a growing civil and military airport in the northern part of Denmark. Situated close to the water, with large meadows and huge areas with flooded pastures in the immediate surroundings, managing wildlife is a challenge. Add a rapidly growing Barnacle goose population, and you have a problem. So, what were we to do?

We started by implementing a strict digital recording of all wildlife movements in the area. This lead to a better understanding of the bird behaviour. Due to the digital recording, we were able to map where and when our high-risk species were present and to track their local migration patterns.

Avoid bird strikes - Image from Ascend XYZ digital recording solution, showing wildlife recordings based on wildlife risk level in a 4-hour period on the 21st of February.
Image from Ascend XYZ digital recording solution, showing wildlife recordings based on wildlife risk level in a 4-hour period on the 21st of February.

With this information in hand, we started to focus on our active measures — extra “boots on the ground” in high-risk periods, new tools (e.g., remote controlled gas canons, structured hunts) to target and change local migration patterns. This, combined with education of the bird control units and strong management support, has yielded results. We went from 37 bird strikes (2016) to only 18 strikes (2017), and that with movements increased by 8 %.

What’s next for us?

In 2017 Aalborg airport was a part of the Airshare XYZ project. The Airshare XYZ project currently is supported by 13 European Airlines and more than 90 airports globally. The project is focused on sharing the knowledge, understanding how other airports and airlines are mitigating risks, what works and what doesn’t, and how we get the best effect of the measures we take. We hope to see our colleagues around the world participating and sharing their knowledge in this field.

Aalborg Airport is the first airport in Denmark to install an Avian Radar. Avian Radar allows us to give our bird control units real-time information on bird activity in the airport operations area, enabling them to take immediate actions. By combining our digital recording data with radar data, we expect to gain important insights on the effect of our area management plan. Last but not least, we will be able to map bird activity in our surroundings. It is exciting times — possibilities, understanding, and technology are changing the way we perform wildlife control and reduction. I hope this post inspired you to share insights from your Airport or Airline with the rest of us.

For more information contact Thomas Hugo Møller (Aalborg airport) on LinkedIn.