Enhancing FOD Control with Artificial Turf

In Toledo, Ohio, the airport installed a 10-foot fence to replace a six-foot fence around its perimeter.

They did this to keep wildlife away from their safety zones. In their case, the wildlife included a 200-pound deer grazing along its runway.

As airports grapple with FOD control, they seek effective ways to keep wildlife and foreign debris away from runways and taxiways. Airport facility managers have used everything from pyrotechnics and nest egg removal, to decoys and predatory Falcons.

According to the FAA, aircraft wildlife strikes are a serious cause of aviation-related accidents and fatalities. Between 1990 and 2004, there were more than 59,000 wildlife strikes to commercial and military aircraft. The strikes caused damage to some 7,300 civil aircraft and substantial damage to 2,000 of them. During this period, the strikes destroyed 19 aircraft, injured 134 individuals, and resulted in eight fatalities. The FAA estimates this damage alone to be $4 billion, with associated losses of 4.7 million hours of aircraft downtime due to these strikes.

According to a 2004 research report by the FAA, birds are involved in 97% of the reported strikes, mammals in 2.4 %, and less than 0.2% involve reptiles. Gulls, raptors, blackbirds, waterfowl, and doves (including pigeons) were the most commonly struck bird groups. The most frequently struck mammals were deer and coyotes.

There's a new solution making its way onto the runway safe zones that just may curtail the source of thousands of FOD incidents that occur each year.

Air FieldTurf™ is a new artificial turf product line specifically developed as a safety enhancing surfacing technology for air carrier, military and general aviation airports. The patented turf product line is approved for airport installations by the FAA.

FieldTurf, the parent company, is responsible for the majority of artificial turf on professional playing surfaces around the world, including many within the NFL and the NCAA. They revolutionized the ground beneath the feet of professional athletes over a decade ago, and now, with 40 plus international patents under their belt, have transferred their technology to the aviation environment.

The artificial turf is manufactured as a polyethylene fiber that is 120 microns thick, and tufted into a black mesh backing with a depth that ranges from 2 to 2½".

It is ballasted with approximately 1½" of silica sand infill, which is trapped in the unique geometric structure of the artificial blade fiber.

For starters, it does not support food, water or shelter - which wildlife depend on and build their habitats about. And according to the FAA, this is precisely what an airport's Wildlife Hazard Management Plan is intended to resolve.

According to the report Wildlife Hazard Management at Airports, published jointly by the FAA and the USDA in 1999, "The goal of an airport Wildlife Hazard Management Plan is to minimize wildlife populations on and around the airport that pose a threat to aviation safety or to structures, equipment and human health.

The joint report goes on to say, "Habitat modification means changing the environment to make it less attractive or inaccessible to the problem wildlife. All wildlife needs food, cover and water to survive. Any action that reduces, eliminates or excludes one or more of these elements will result in a proportional reduction in the wildlife population at the airport."

In addition, FAA Advisory Circular 150/5200-33, Hazardous Wildlife Attractants on or Near Airports states, "Land use practices that attract or sustain hazardous wildlife populations on or near airports can significantly increase the potential for wildlife-aircraft collisions."

"There are thousands of species of wildlife out there and this increases the risk of FOD," explains Joe Dobson, Vice President of Air FieldTurf™. "Wildlife seek food, water and shelter. Air FieldTurf™ does not support food, water or shelter, and therefore mitigates wildlife from forming a habitat in or around the runway and taxiway areas -- and it does this non-lethally."

"Birds rely on food, water, and shelter for survival. If you eliminate these environmental conditions, than you essentially eliminate the problem with birds," says Alex Orosz, FOD Manager for United Airlines. "However, most airports are more concerned with operations and aesthetics. Airports not only want to beautify the airfield, but also make a clear distinction for pilots between the infields and the runway/taxiways. Traditionally airports have used a natural surface such as grass to fulfill this need; unfortunately, it is grass that is the root of the problem. Natural grass pools water and attracts birds in addition to eroding on the edges, which contributes to an increase in FOD damage."

"Air FieldTurf™ specifically addresses that need," says Orosz. "It seems to be a good solution for all as it beautifies the airport, gives contrast for the flight crews, and mitigates wildlife because it does not attract birds."

According to Orosz, Air FieldTurf™ took the initiative of mitigating wildlife one step further and insured that this is a safe product, one that airports and airlines are satisfied with, by testing it with the FAA. "United [Airlines] participated in that testing because any damage that arises from wildlife trickles down to us. Ultimately it is the airlines who pay for that damage when it occurs," says Orosz. "So we supported the testing by first taxiing our aircraft over the artificial surface and parking on it. This test ensured that the artificial surface had weight-bearing capability and would not rut if an aircraft had to swerve into the infield during an emergency. We also took various types of aircraft (Boeing 747, 757 & 777) and performed engine tests adjacent to the infield to establish if there was any burning or peeling. All of the tests were successful as the Air FieldTurf™ product did not exhibit damage nor liberate any material."

Groundbreaking tests also were conducted in a military setting, using the C-5 Galaxy and C-130 Hercules heavy transport aircraft as well as the CH-53E Sea Dragon helicopter. These demonstration projects showed that the turf remained stable against the pressures of jet blast and repetitive take-offs and landings from military aircraft that typically displace significant amounts of natural turf.

According to Orosz, FAR 139.337 specifically dictates that every airport requires an environmental program in order to be certified by the FAA, and some of the larger airports even have wildlife biologists on staff. Smaller airports typically have someone that analyzes the airport environment and makes recommendations to the airport management by providing a plan that is feasible financially, operationally and in terms of safety.

Orosz points out that about 5-10% of wildlife strikes are either ingested or are large enough to cause damage to the radome or the wing. Orosz further comments, that although an ingestion may not affect the flight, upon inspection, once the airplane lands at its destination, a pilot or mechanic will inspect the impact and follow-up with corrective action. "At times the damage can be easily fixed by simply repairing or replacing fan blades, but sometimes the aircraft must be taken out of service and the whole engine removed to be repaired," he explains.

Orosz adds that, "when a bird is ingested into an engine, rest assured that the plane is designed to withstand the ingestion. However, about 5% of the time, when the bird is large or there are numerous birds, the ingestion is substantial enough to force an engine removal. The cost of this repair could escalate to well over a million dollars in addition to operational delays or cancellations. It is these events that motivate us to continually improve our FOD and safety programs as well as assist the airports in improving theirs with revised processes or technological advancements."

Can Artificial Turf Create FOD?

To insure that artificial turf was not a source of FOD, Air FieldTurf™ was tested extensively to determine if it could fragment or levitate and blow onto the runway or taxiway area.

The turf was tested at San Francisco International Airport, utilizing the jet blast from United Airlines' Boeing 747 and 777 commercial jets. In addition to the tests at SFO, similar tests were performed at Boston Logan International Airport using a United Airlines Boeing 757.

"The normal power setting of aircraft operating on or around the turf is for taxi mode," explains Dobson. However, the turf integrity was tested to insure that, if an aircraft had to accelerate to transit to its runway, a surge of jet blasts would not be able to move the turf. The blast settings were taken at different angles to the turf, as well as at different power settings. The turf successfully remained intact and did not levitate or break off at all. In addition, when the pilot veered onto the turf to see if the surface rutted or created any further source of FOD, it did not.

One explanation of why the turf stayed intact is its method of installation. The installation follows a specific procedure and is normally accomplished in an 8-hour window during an airport's overnight shift. The subgrade may be prepared to be a load bearing or a non-load bearing base. The turf may also be specified as permeable or non-permeable, depending on the drainage requirements of the site.

It is first anchored to a 6" x 6" curbing made from recycled plastic, which butts to the runway or taxiway's asphalt shoulder. This curbing is anchored with 16" x 5/8" steel rebar and has a 2½" x 1½" notched recession. The turf carpet is glued to this recession and further secured with nails. The opposite end of the turf is trench-buried in a 12"-deep trench, pegged, and backfilled. The trenched turf, in combination with the curbing header, gives it a firm footing.

The entire turf is then in-filled with silica sand. This sand is brushed into the turf to firmly ballast and anchor it.

The resulting turf area greatly reduces the risk of FOD and provides a "sterile" environment around the runways and taxiways. "Our product is manufactured just like shag carpeting," explains Dobson. "In fact, the product is manufactured right alongside other carpeting in Dalton, Georgia."

Dobson explains that, when a 747 or 777 taxis into a runway at the rotation points, the jet blast often blows out natural vegetation onto the runway. "With the curbing, the trench and bury, and the infill sand, we have proven that the carpet is going nowhere," he says.

The Ocean City Municipal Airport is located on the New Jersey shoreline and the airport installed sections of Air FieldTurf™ in the fall of 2004. "We have a major bird problem here," explains Bill Colangelo. Colangelo is the Manager of Public Transportation and Revenue Collection for Ocean City and oversees the management of the municipal airport. "As far as I've seen, the geese have totally stayed away from it."

The beauty of an artificial turf product is its wildlife deterrence without harm. Dobson points out that installation of the turf causes wildlife to form habitats elsewhere, thus mitigating wildlife non-lethally.

About 90% of all bird strikes in the U.S. are by species that are federally-protected under the Migratory Bird Treaty Act. According to the FAA, a 12-lb Canada goose struck by a 150-mph aircraft at lift-off generates the force of a 1,000-lb weight dropped from a height of 10 feet.

FAA data cites that 25% of the bird strikes reported from 1990-2002 were not reported on FAA Form 5200-7. When FAA Form 5200-7 is not used, important information is often omitted. Because of this, the database manager must make additional contacts with the parties involved. As more strikes are reported each year, it will become impossible to follow up on every strike to obtain missing data. This means that the problem of bird strikes to aircraft, in general, will remain understated. Things are improving since reporting is available electronically. According to the FAA, there has been a 28 % increase in electronic reporting since this feature was introduced; however, data is still found to be under-reported and incomplete.

Incomplete reporting is common as aircraft owners wrestle with a competitive environment. Dobson concurs that most bird strikes are not reported to the insurance companies. "Airlines often find that they can pull an aircraft into their hangar, fix the damage and get it quickly back out into their fleet."

Airport management has a responsibility to insure an environment where an aircraft can land safely with minimal risk of a wildlife strike. Commercial aviation places much trust in the airport runways and taxi protection zones as being just that - safe. When a 747 lands at an airport, the landing fee is supposed to insure access to the runway and taxiway, but also to insure the safety of that aircraft. "This includes wildlife maintenance, FOD, the whole nine yards," states Dobson.

With artificial turf, the wildlife find a new habitat out of harm's way. It is safer for them and much safer for aviation operations.

In addition, FAA Advisory Circular 150/5200-33(link at end of paragraph), Hazardous Wildlife Attractants on or Near Airports states, "The movement of storm water away from runways, taxiways, and aprons is a normal function on most airports and is necessary for safe aircraft operations" . Because pooling and ponding water can attract wildlife, the same FAA Advisory Circular states, "If soil conditions and other requirements allow, FAA encourages the use of underground storm water infiltration systems, such as French drains or buried rock fields, because they are less attractive to wildlife. (http://www.faa.gov/airports_airtraffic/airports/environmental/policy_guidance/media/ac_5200-33.pdf)

A key advantage of Air FieldTurf™ is it is engineered with excellent drainage characteristics. It is available in permeable and non-permeable designations.

The non-permeable turf allows run-off from two to three percent grade of the asphalt shoulder, which butts up to the concrete runway or taxiway. The water runs down the asphalt shoulder, across the turf and into the airport drainage system. Air FieldTurf™ has some additional benefits, which dampen the environmental effects of any hazardous spill or contaminant, which might leak into the soil.

The permeable turf percolates at a rate of 60 gallons per square foot per hour. After a heavy rain, the soil of the shoulder area can become saturated and leave standing water on or near the runways or taxiways. Pooling and ponding of water is a potential hazard for transiting aircraft, as it may create a hydroplaning effect, which can cause an accident or serious damage.

With Air FieldTurf™, water percolates through it and is quickly gone. Even with a heavy deluge of rain, the turf is designed to drain quickly.

When the FAA tested the turf, they applied water to simulate a pooling effect to see how water percolates through it. Most of the water percolated through in two to three minutes and was completely gone within five minutes. After 30 minutes, the area was dry to the touch.

Air FieldTurf™ deters the wildlife's habitat, which greatly reduces FOD. While its installation requires an initial investment, its payback is noteworthy. FOD control is one part of the payback. But, by replacing natural vegetation, there is a definite reduction in maintenance costs afforded to airfield management. The reduction in total lifecycle costs associated with an Air FieldTurf™ installation is quite attractive and factors well into its return on investment.

While competing asphalt systems may serve as a wildlife deterrent, they do require periodic maintenance such as seal coating and over pavement, and are also subject to erosion on the shoulders due to jet blast. Air FieldTurf™ outlasts the asphalt by a factor of three and, if there is minimal maintenance performed on the turf, that number usually jumps up to a factor of four. In addition to its superiority over asphalt, there is much to be saved on the maintenance and care of the landscape it replaces.

Dobson explains that Air FieldTurf™ requires minimal maintenance, when compared to grass and natural vegetation. "Without natural groundcover to maintain, the problem of damaged navigational lights from mowing, noise from the mowing equipment, third-shift labor premiums, and mowing equipment emissions are no longer issues," he says.

In addition, a seeded area is often washed out or blown out from heavy rains or jet blast, requiring sod replacement. Over-seeding is also required periodically. Artificial turf remains sterile and clean, and no herbicides or pesticides are required.

When it comes to wildlife deterrence, there's even more reason to avoid seeding runway areas. That is part of the payback regarding FOD control. According to the FAA's Office of Airport Safety and Standards, CERTALERT No. 98-05 was issued because of reports of airport owners or airport contractors planting disturbed areas with seed mixtures containing brown-top millet. According to the document "All millets are a major attractant to doves and other seed eating birds that may pose a strike hazard to aircraft."

And there are other indirect costs that go along with natural turf. According to Dobson, once a light gets mowed over, an electrician not only needs to change the light, but must do so during an off-hour so as to not interfere with operations. This results in added labor and overtime costs. If the ground is soaked and not amenable to mowing, the mowing must wait, and the grass just gets higher. But the FAA has limitations on the height of the grass, so maintaining natural turf can be a costly venture.

"I see it [Air FieldTurf™] as a Godsend" says Colangelo. "Lights and signs have been a major problem [as an obstacle to mowing] for us." Colangelo explains that he is always bringing visitors out to the airfield to see the product and drive on it. He believes that the turf's safety attributes are most enticing; however, the culmination of all of the product's features makes it most appealing for his operation.

Yet another collateral benefit of the turf is the view it provides from above. Because Air FieldTurf™ is evergreen, in all seasons, the product contrasts with the adjoining asphalt or concrete runway or taxiway. Such contrast gives a very clear landing target and significantly enhances pilot visibility.

"The pilots love it," says Colangelo. "They say it's just so much easier to judge the runway from above."

"If I didn't feel that a product like Air FieldTurf™ would make a big difference, I wouldn't have supported the testing with the FAA," says Orosz. "I see the viability of the product. I see that its success will ultimately help United. I also see that this product can benefit the mitigation of wildlife at airports worldwide."

Air FieldTurf™ As A Wildlife Deterrent: How Big Is The Problem It Reduces? [1]

U.S. civil aircraft reported over 5,900 bird strikes in 2003, however, an estimated 80% of bird strikes to U.S. civil aircraft go unreported each year.
Reported losses from mammal strikes totaled 211,421 hours of aircraft downtime and $31.52 million in damages.
Gulls (25%) doves (14 %), raptors (12 %), and waterfowl (10 %) were the most frequently struck bird groups.
About 71% of the reported strikes occurred at or below 500 feet above ground level and 36 % occurred when the aircraft was on the ground during takeoff run or landing roll.
A 12-lb Canada goose struck by an 150-mph aircraft at lift-off generates the force of a 1,000-lb weight dropped from a height of 10 feet.
The North American non-migratory Canada goose population increased 3.6 fold from 1 million birds in 1990 to 3.6 million in 2003. Canada geese were responsible for a disproportionate amount of damage. They were involved in 5 percent of all reported bird strikes and 19% of the cases where a bird strike caused damage to the aircraft.
Deer and coyote are the most frequently stuck mammals.
Since the first release of 60 European Starlings in New York's Central Park, in 1890, this type of bird now represents the second most abundant bird in North America with a late-summer population of over 150 million birds. Starlings have been called "feathered bullets", having a body density 27% higher than herring gulls.

[1] Source: Wildlife Strikes In The United States , Report Of The Associate Administrator Of Airports Office Of Airport Safety And Standards, Airport Safety & Certification , Washington, DC, June 2004 http://wildlife.pr.erau.edu/Bash90-03.pdf

Enhancing FOD Control with Artificial Turf By Jim Romeo

Enhancing FOD Control
with Artificial Turf
By Jim Romeo