Kodiak Airport EIS Project Update Message – February 2012

Kodiak Airport EIS Project Update Message – February 2012
You’ll recall from the update I sent in January that a runway safety area (RSA) is an area
surrounding the runway that reduces the risk of damage to an aircraft if it deviates from the
runway. The size of a RSA typically depends on the largest and heaviest aircraft regularly
operating on that runway. Two of the runways at Kodiak Airport, 18/36 and 07/25, do not
meet RSA design standards for those aircraft. The traditional runway safety area consists of
graded areas at the runway ends and along the sides of the runway to offer aircraft protection
in the event of an overrun or veeroff during takeoff or landing. To meet the FAA’s
dimensional standards for RSAs at Kodiak Airport, sufficient fill would have to be placed at
the north (toward the Buskin River) and south (into Womens Bay) ends of Runway 18/36 and
the east end of Runway 7/25 (into Chiniak Bay) to create a graded surface that measures
500 feet wide by 1,000 feet long.
FAA is considering alternatives for Kodiak Airport that could lessen environmental impacts
caused by the fill and large disturbance areas associated with a conventional RSA
construction on the runway ends. One option is the use of Engineered Materials Arresting
System, or EMAS. The Preliminary Draft EIS distributed to agencies and tribes late in 2010
included one alternative incorporating EMAS. Engineering and operational analysis since
that time confirms that it may be a feasible technology for both runways, and I expect the
Draft EIS will consider alternatives incorporating EMAS on the north, south, and east runways
ends. I’ll use this update to provide some explanation of how EMAS works, where it has
been used, and some of the benefits and potential drawbacks of this technology.
What is EMAS?
A conventional runway safety area provides a substantial additional amount of land for an
aircraft to slow down and stop; for runways 18/36 and 7/25 at Kodiak Airport, the requirement
would be 1,000 feet beyond the runway ends. However, at many airports it may not be
practicable to build enough safety area at the runway ends to meet FAA standards. Existing
roads or railroads, natural features such as water bodies and large terrain changes, or
environmentally sensitive areas are among the reasons why it may not be prudent to
construct a conventional RSA. The FAA began conducting research in the 1990s to come up
with an alternative way to stop aircraft without requiring as much land as a conventional RSA.
Working in concert with the University of Dayton, the Port Authority of New York and New
Jersey, and the Engineered Arresting Systems Corporation (ESCO) of Logan Township, NJ,
a new technology, EMAS, emerged to safely arrest overrunning aircraft.
EMAS consists of a number of pre-cast, crushable, and energy-absorbing cellular cement
blocks installed at the end of a runway. The material in these blocks may be thought of as
something similar to pumice, a type of very light volcanic rock with lots of holes and
airspaces. An aircraft that hasn’t stopped by the runway end encounters “lead-in” blocks that
begin to crush under the movement and force of the wheels. The material in the EMAS is
designed to slow an aircraft by increasing the resistance, or friction, of the wheels as the
material gets crushed. The landing gear of the aircraft sinks into the “pumice-like” material
and the aircraft slows down as it gets further into the EMAS. How quickly the EMAS slows an
Page 2 of 4
aircraft is dependent on a number of factors including the weight of the aircraft and entry
speed, landing gear configuration, and even tire pressure.
Nice Theory, but does EMAS Really Work?
Currently, EMAS is installed at 63 runway ends at 42 airports in the United States, and on
five more runway ends at three airports outside the U.S. By the end of 2011, there had been
eight incidents where EMAS safely stopped overrunning aircraft carrying a total of 235 crew
and passengers, including incidents at JFK Airport in Queens, New York; Key West Airport in
Florida; and Downtown Greenville Airport, South Carolina. Obviously, EMAS can help
protect human health and safety, and it has worked with relatively little damage to the aircraft.
But it is also important to remember that EMAS really represents a component of runway
safety area that was used because of physical or environmental constraints unique to a
particular runway. A successful aircraft arrest by EMAS illustrates the value of FAA’s runway
safety area program, and there are many similar examples where conventional RSA has
provided the additional land needed for an aircraft carrying crew and passengers to come to
a complete stop, with little damage. If you are interested in more information about incidents
involving EMAS or locations where it has been installed, you might consider looking at FAAs
most recent fact sheet at
http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=12497.
Could EMAS be Used at Kodiak Airport?
FAA has determined that a properly designed EMAS will provide a level of overrun safety
generally equivalent to a standard runway safety area. And, as we know from the past 10+
years of experience, the technology works. Typically, FAA and Airport Sponsors (the owners
and operators of airports) consider installing EMAS on runway ends where space is limited
and a standard RSA is not feasible. EMAS may also deserve consideration in other
situations, even where standard runway safety area is considered practicable. For example,
because EMAS requires a smaller disturbance footprint than conventional RSA, its use could
lessen damage to sensitive environmental resources beyond runway ends. Some of these
reasons apply to Kodiak Airport.
A conventional RSA for Runways 18/36 and 7/25 would be 500 feet wide and extend 1,000
feet from the runway ends. To provide an equivalent level of safety at Kodiak Airport, an
EMAS would have to be capable of stopping a Boeing 737-400 (the “design” aircraft) that is
still traveling at a speed of 70-knots when it exits the runway. The EMAS required to achieve
this performance would be about 340 feet long and 170 feet wide. However, for runways like
Kodiak’s that have instrument approaches or visual guidance lighting, there must still be at
least 600 feet of RSA to protect aircraft landing short of the runway. To meet all of these
requirements, the final design would consist of 260 feet of conventional, graded RSA
immediately after the runway end, followed by 340 feet of EMAS for a total RSA length of 600
feet. Although the EMAS itself would only be about 170-feet wide (slightly wider than the
runway) it would be surrounded by traditional RSA out to the standard 500-foot width. The
net footprint for a RSA incorporating EMAS that meets FAA standards for the design aircraft
Page 3 of 4
would therefore be 600 feet long by 500 feet wide. (If that is all a little confusing, don’t worry,
we are developing figures for the Draft EIS that should be easy to follow!)
Other Important Considerations for Kodiak
Although EMAS may have appeal for some applications, it also has some potential
drawbacks. EMAS can be more expensive to construct and maintain than a traditional RSA.
Each EMAS is designed according to the specific needs of the airport and runway at which it
will be installed. The cellular concrete blocks, coatings, and other materials all have to be
shipped to the airport from the manufacturing facility in New Jersey. Further, EMAS will have
a limited design life (currently 10 to 20 years) and may have to be replaced, at another
substantial cost. Blocks that are damaged during routine airport functions or as a result of
aircraft arrest would need to be manufactured and replaced.
EMAS also has maintenance and care requirements that don’t apply to a conventional RSA.
For example, special equipment designed for use on EMAS is needed to drive on the
arresting bed, or to clear snow without fear of damaging individual blocks or system integrity.
A system of sealants, coatings, and outer layers protect the cellular concrete from
environmental conditions such as rain and ultraviolet radiation. Older versions of EMAS
needed periodic re-painting, although the manufacturer asserts that the improved plastic seal
coating for newer models should eliminate the need for painting and sealing.
An issue we have discussed with respect to Alaska airports concerns the practicality of using
EMAS in more challenging climates or environmental settings. Kodiak Airport exhibits some
of these factors including cold temperatures, frequent freeze/thaw cycles and a relatively wet
environment, especially at the runway ends exposed to waves and salt spray. In particular,
FAA Order 5200.9 acknowledges that local climate conditions consisting of “extreme cold
location with high flooding potential might limit the effectiveness and/or durability of an EMAS
installation.” Runways at Kodiak Airport, particularly runway end 25, can be exposed to high
waves that wash onto land. The strong energy behind wave action can carry rocks and other
materials that could damage the surface. A common concern for coastal airports has been
that salt water could have an especially corrosive effect on materials, coatings and sealants.
FAA and Airport Sponsors, among others, had also been uncertain as to how EMAS would
perform in locations with extremely cold temperatures, prompting research funding to the
Corps of Engineers Cold Regions Research and Engineering Laboratory to assess the
durability of EMAS in cold climates.
ESCO has responded to concerns about the resilience and durability of earlier EMAS
versions by developing the so-called 3rd generation product, known as “EMASMAX.”
According to the manufacturer, this version improves on earlier systems with better protection
against moisture penetration and jet blast protection, among other enhancements.
Regardless of specific climactic or environmental conditions, it is clear that frequent
inspection and regular maintenance are important factors to a viable, long-lasting EMAS.
(For the purpose of this update, “EMAS” refers to any version of the arresting system.)
Page 4 of 4
EMAS is currently being used at one location in Alaska, installed on Runway end 27 at
Cordova in 2007. As you know, Cordova has experienced a particularly difficult winter, with
heavy precipitation. At this time, we don’t know if or how the extreme weather and
tremendous snow loads have affected integrity of the Cordova EMAS. I know ADOT&PF, the
Cordova Airport “Sponsor”, is particularly keen to find out if there have been problems. I’ll let
you know when more information with this local-to-Alaska EMAS application becomes
available.
One interesting question, certainly applicable to Kodiak Airport and raised during our
meetings in November 2011, concerns the ability of EMAS to withstand a ground-shaking
event. Put another way, what magnitude of seismic event (i.e., earthquake) could an EMAS
handle – in terms of materials integrity, seam adhesion, sealant durability and so forth –
without requiring repair or replacement? I’m not aware of any testing has been conducted to
specifically answer this question. In practice, immediately following an earthquake a Sponsor
would quickly inspect all airport facilities to determine if they are in acceptable condition to
resume service. However, damage to an RSA, or an EMAS installed as part of the safety
area, should not prevent normal aviation operations from resuming, although it would then be
important to replace any damaged components of the EMAS as soon as possible after an
event.
In fact, this scenario is very much similar to the sequence of events after an aircraft overrun
into EMAS. An aircraft arrested in EMAS would be removed from the airfield as soon as
possible after immediate response activities have concluded; typically, this happens within a
couple of days or even hours after the accident. At that point, FAA will issue an official notice
to airman of the change in conditions at the airport, but service on the applicable runway
returns to normal relatively quickly.
Summary
EMAS represents a safety technology for aircraft overruns that can be comparable to
traditional, grade and fill runway safety area. The potential benefits of EMAS, particularly by
lessening adverse impacts on marine habitat and wildlife, have led FAA to conclude it should
be a component of some RSA alternatives to be evaluated in the EIS. We will work hard to
make sure the EIS provides a reasoned analysis of the benefits and drawbacks associated
with installation and care of an EMAS at Kodiak Airport.
Thanks so much for your interest in the project. I hope these updates are informative, but
don’t hesitate to let me know if you have questions, comments or concerns. My phone
number is 271-5453 or you can email Leslie.Grey@faa.gov.
Regards,
Leslie Grey
Environmental Protection Specialist
FAA - Alaskan Region, Airports Division
907-271-5453