View Full Version : Repelling the Birds

7th Oct 2004, 16:00
There is a weird (up to me) procedure in the company where I fly: "Turn On the radar during Take off and landing to repel the birds".

Do you think this can be predicated on a scientific research?


7th Oct 2004, 16:43
Well I guess there must be some science behind it since the CAA sees it as a potential mitigating measure in avoiding a bird strike -refer to Page 9.


7th Oct 2004, 16:45
Does it work on Cabin Crew? :cool: :cool: :O

8th Oct 2004, 01:55
As far as I know, there is no technical support for using this concept as an additional active radar system aboard an aircraft.

Its use is envisioned only as a research tool as ground fixed radar arround target airports, to study flocking behavior over a time period.

8th Oct 2004, 02:28
You might wish to read the CAA article with care. It clearly states that there is no scientific evidence to support the use of radar as an aircraft bird hazard deterrent.

I have been closely involved in bird hazard research for a number of years including researching, validating writing five chapters and editing a book on bird strike information for Transport Canada, titled "Sharing the Skies" available to read on-line at www.tc.gc.ca) I can assure you there is no data to support the use of weather radar and the low power output of aircraft weather radar is too low for birds to detect. I researched all available material and spoke at length with experts in the field of bird biology and radar and they clearly confirmed that with low power output and the understanding of bird sensory capabilities that that it is highly unlikley that they can sense radar, mucch less understand what to do about it.

This is essentially an urban legend that may heave been fostered many years ago from anectdotal information from pilots of military aircraft that used early fire control radars that operated at significantly higher power outputs than current weather radar.

Richard Sowden
A320 Pilot & Bird Strike Researcher

Capt Claret
8th Oct 2004, 13:06
G'day Canuckbirdstrike

You might be interested in some research in Australia that was published in the last 6 months or so. I did not see the whole story on the news and thus my information is sketchy.

As best I can recall, the researcher, attached to one of the universities in Brisbane I think, has determined that bird strikes at aerodromes can be reduced by a sginifficant margin, by allowing the grassed areas surrounding runways and taxiways to grow to an "ideal" length, instead of keeping it mowed short as is the usual practice.

It seems that research has shown that short grass attracts insect feeding birds. Grass that is too long will harbour too many ground dwelling mammals/rodents and the like and thus attract birds of prey. The ideal length is some where in the middle, such that insect feeders can't get at the bugs, and the small animals find no cover, so the birds of prey aren't attracted.

This link (http://education.qld.gov.au/marketing/service/higher-education/university/qld-unis.html) will give you links to the various QLD universities.

8th Oct 2004, 14:05
The ideal length for grass alongside the runway is a function of time of year and subject bird specie. The concept of one size fits all does not work.

The concept of trying everything does have some effect.

8th Oct 2004, 14:34
We introduced a so-called 'long grass' policy here in the UK at civil and Royal Air Force aerodromes in the 1970's. (The Fleet Air Arm of the Royal Navy continue with a radically different birdstrike reduction philosophy). Actually, this is part of a carefully managed habitat control regime. The grass is kept at 200-250 mm for much of the year, especially when the invertebrates in the topsoil are an attractant for smaller flocking birds, starling, lapwing etc. This policy AT A STROKE reduced bird populations on aerodromes by over 50%. Thus, we've avoided a disastrous strike on a flock of such birds. However, as the CAA's leaflet points out, there is concern about the increase in numbers of large flocking birds, such as Canada Geese. Just confining our activities to the aerodrome simply won't do to combat this threat, so we look in a 5NM radius all around us.

Thanks, Richard, for the pointer to yet another valuable resource. All knowledge gratefully received. I'll pass it on to
my colleague at LGW who specialises in bird control.

BTW, is it possible that the company that asks its crews to turn on the wx radar are doing so as a bottom-covering exercise? A bit sad if it's so.

The Odd One

8th Oct 2004, 17:44
To all:

Reference the grass cutting issue, I am intimately familiar with this tool and I suggest reading "Sharing the Skies", there is excellent information on this mitigation strategy. However, care must be taken when employing this strategy that the bird risks are clearly identified and the grass height picked to deter the high risk species at the airport in question. Further to this you must also carefully consider that by chnaging the grass height you may attarct other birds in the process.

The odd one, I applaud you for looking beyonf the airport boundaries to deal with bird hazards- this is essential. Currently I am working on a number of projects in this area including finishing the development of a "Bird Aircraft Risk Model" that allows you to assess the high risk areas around any airport based on the aircraft types using the airport, the runway configurations and the local hazardous bird species. This allows you to identify the high hazard areas on the ground and examine local land uses for dangerous practices and work with local authorities to mitigate those hazardous land uses. In addition I am working with a team that will be developing updated policy on land-use in the vicinity of the airport to mitigate bird strikes. A final project is pariticipation in committee that is dealing with the Canada Goose problem in the Toronto area throught the development of coordinated startegies with all the local stakeholders.

Finally on the radar issues - you are absolutely correct many companies put this in as SOP to cover their backsides, but many do it based on the belief tha it actually works.


Capt Fathom
10th Oct 2004, 12:03
Along Similar Lines (http://www.pprune.org/forums/showthread.php?threadid=131275)

Lu Zuckerman
10th Oct 2004, 14:43
There is an American firm that has created an artificial turf similar to Astro turf only the artificial grass is not as dense. The supporting material is open and once the turf is in place it is covered with sand. The sand works its way between the grass blades and anchors the artificial turf to the ground. Although it is designed to provide a better means of seeing FOD that has blown off the runway it does not support insect growth and this means the birds have nothing to feed on.

It is presently being tested at MCAS San Diego. One of the demonstrations was to make sure that jet blast and prop wash would not dislodge the turf. This was done using a C-130 and two FA-18s. It stayed in place. It is being strongly considered for use in professional football stadiums since it is more like real grass in that the sand makes it a bit less grating on the skin and it is softer to land on.

:E :E

10th Oct 2004, 15:32

I am aware of the artificial turf product. I believe it may have great value for airfield areas where access by Wildlife Control personnel is problematic and there have been problems with insects attracting birds. One of the big problems with this product is cost. The product cost could literally use up an entire wildlife management budget in one shot, so it will need to be installed slowly over a number of years and in high risk, difficult access areas only. In addition there have been concerns expressed over the sand anchoring method and FOD damage to aircraft. This is a very vaild concern and the FOD damage from sand is very costly to operators by reducing overhaul times and increasing fuel consumption.

The most important considerations for managing wildlife at an airport are; identifying the high-risk bird species and building an integrated wildlife management plan. There are no "silver bullets" to manage wildlife, rather management plans that consider habitat modification strategies to reduce bird attractions as a long term management strategy, supplemented by the use of patrols and scaring techniques to deal with tactical problems.

Wildlife management is a complex ever-changing exercise that relies on a "tool-box" approach - rather like building a house you don't just use a hammer - you use the correct tool for the correct problem. Most importantly you must always collect data and constantly re-evaluate your strategies as new hazards may appear or appear at different times.


10th Oct 2004, 16:42
Just a shot in the dark but would flashing on and off the landing lights have any affect
Other than confusing the tower?

10th Oct 2004, 20:55
On the subject of pulse lights or flashing lights a study was done back in the 90's by the Transportation Development Center (the research arm of Transport Canada) and the preliminary results showed only very minor physiological responses from birds in cages areas to flashing lights. The results were so poor that Phase II of the project (use of lights and testings with aircraft) was cancelled.

According to colleagues that I work with that are knowledgeable bird biologists, bird visual sensing and processing of these pulsing lights does not invoke a fear response. In fact in many birds and mammals lights will invoke a "freezing' response. Birds and mammals vision is more adapted to detecting movement than recognition of particular subjects, hence when confronted many will freeze believing that they will not be seen.

To my knowledge there is no scientific evidence that indicates that flashing aircraft lights make an aircraft more visible to birds and/or causes them to move out of an aircraft path.


Old Smokey
11th Oct 2004, 13:36
Canuckbirdstrike has come up with some VERY impressive information, not just now, but on previous occasions. It makes this post almost pale into insignificance, but in respect of the original post regarding RADAR effectiveness against birds -

Having heard the folk-lore on numerous occasions I've experimentally tried zapping birds with the radar at close and medium distances, both with the 'old' high power radar, and the newer low power units. None of them had the slightest effect. (Maybe it will on future generations of genetically modified birds).

I believe that the theory originated in England in WWII when birds nesting on the stationary RDF transmitters were microwaved on the spot by the very high energy emissions. (I stand ready to be corrected on this).

11th Oct 2004, 13:56
Bologna is the only airport on my travels that recommends that the use of radar is advised to avoid bird strikes!!! i knew it was cr*p and glad to see the big guns feel the same way also.

11th Oct 2004, 14:55
I remember reading that some airports had problems with seagulls dropping shells on the runway to crack them open, then landing on the runway to eat their meal, making the birds and shells a hazard.

A network of stainless steel cables strung across open
spaces will prevent seagulls from diving on public areas
where they compete with humans for burgers and fries.
A real problem exists with gulls at seaside airports
where birds drop clams and other shellfish on the
runways to break the shells. In one instance the birds
stopped dropping their clams at one airport when a
clever PCO painted seagulls flying in a search pattern
(as seen from the top) on the runways. The flying birds
were afraid to drop their shellfish, lest the "other
seagulls" get to it before they do.

From page 3 (of 28) of this PDF file:

11th Oct 2004, 15:59
One of the fascinating things about the bird strike business is the proliferation of all kinds of tools and techniques that "reduce bird-strikes, guaranteed". Unfortunatley, the vast majority of these claims have zero basis in any scientific study and are hearsay and anecdotal information only. When attending conferences on bird strikes I am amazed at the vendors displays and the wild claims that some of them make. It reminds me of the "snake oil" salesmen from the early part of the 20th century.

This is not say that there aren't good products out there and good techniques, just that careful evaluation of the science (or lack therof) behind the product is important. This must also be coupled with the realization that no single product or technique will solve your bird problems.

Now on to the stringing of cables to discourage birds... Yes, this is an effective technique. You don't need to use steel cables, monofilament line layed out in a grid that is just smaller than the problem bird species landing circling pattern diameter will do the trick. The lines can also be supplemented with mylar strips tied to it. The difficulty can be if you have a large surface area to cover then the construction of the grid can be problematic and may be too easily damaged in high winds.

I am not so sure about the real scientific evidence concerning the effectiveness of the painted pictures of gulls. My research and experience indicates that gulls a wiley and when they figure out that nothing happens when they drop clams near the painted birds they will ignore them. It will work for a short time, but not for any extended period of time. The classic example of this is using propane scare cannons in the same location all the time. the birds habituate to them and ignore them. I personally watched a propane cannon at a major airport where the gull would sit on the cannon and ride the barrel as it swept back an forth. The when it heard the propane valve open it would fly away, wait for the bang and return.

Old Smokey, thanks for information on your experience. As for your comments concerning the early ground radars there may be some element of truth in this, but I can't prove it. Some further things to consider is that bird behaviour when confronted by an aircraft may have created this legend. If a bird is approaching an aircraft with the radar on and then subsequently avoids the aircraft by diving or climbing, then this may be incorrectly interpreted as the bird sensing the radar. The more likely cause is a classic escape maneuver and unless control test were conducted without radar there is no validity to the observation. This is the classic example of establishing a cause and effect relationship where none exists that then becomes "fact".


Old Smokey
11th Oct 2004, 16:33
From your last paragraph -
The more likely cause is a classic escape maneuver and unless control test were conducted without radar there is no validity to the observation.
I've observed the classic escape maneuver (wings fully retracted, gravity assisted descent) on countless occasions in both radar equipped AND non radar equipped aircraft. My observation is that it's most likely visual identification on their part, had a number of strikes from their rear end (ouch!), the evaders seem to have us in their line of sight. Hope that this helps.

This is a serious subject, but a bit of levity never hurts. At my old airline one of our F27 captains speared a poor duck straight up the bum with the rather long pitot tubes. Poor old Bluey (and the duck) never lived it down.

Canuckbirdstrike,keep up the very good work, thank you for your considerable efforts in making our crowded skies a little safer.

11th Oct 2004, 16:51
Adding levity to the discussion..... The airline I fly for had a very unusual strike that led to a rejected takeoff...

A bee flew down one of the pitot tubes blocking the airspeed indications and generating an airspeed fault message and RTO.

Another airline hit two wild turkeys on the take-off roll at Washington Dulles with one penetrating the flight deck resulting in an RTO. The comment was "I thought all the turkeys were on Capital Hill not at the airport".