Hello Again!
In December I sent out an update that provided some answers to questions
raised during our November meetings, with a focus on the Kodiak Airport
runways: their dimensions and orientation, and how often they are used by
the different aircraft types, including commercial jets, turboprops, and
Coast Guard planes. This update builds on that earlier message by making
the connection between runway use – particularly the type of aircraft
regularly using a runway – and the applicable runway safety area (RSA)
standards. I will also compare the standard RSA dimensions with what
currently exists at Kodiak Airport.
What is a Runway Safety Area?
In the Advisory Circular Airport Design (#150-5300-13; 1989), FAA has
described the RSA as
“A defined surface surrounding the runway prepared or suitable for
reducing the risk of damage to airplanes in the event of an
undershoot, overshoot, or excursion from the runway.”
I’ll supplement that description a little. By “defined” we mean the RSA
has published dimensions of width, as measured from the runway centerline
to both sides, and length, or the distance of safety area beyond the runway
end. (We usually give these dimensions in feet). So, not only is there
RSA at the runway ends, designed to offer aircraft undershoot or overshoot
protection, but it also is found parallel to and along the sides of the
runway. This lateral safety area provides protection in case an aircraft
veers off during landing or takeoff. Our analysis of Kodiak Airport RSAs
tends to focus on the runway ends, but each of the alternatives for Runway
18/36 also includes improvement to lateral safety area on the east side of
the runway near the Runway 36 end. The attached, simple schematic from the
Airport Design Advisory Circular should help to illustrate the concept.
A way to establish that an RSA is “prepared or suitable for reducing the
risk of damage…” is by requiring it to be capable, under normal (dry)
conditions, of supporting aircraft that deviate from the runway without
causing structural damage to the aircraft or injury to its occupants. RSAs
make airports and flying safer, and reduce the potential for an aircraft to
be damaged if a landing or takeoff has problems. RSAs also make it easier
to get firefighting and rescue personnel and equipment to the scene of the
accident if an aircraft does deviate from the runway.
How are RSA Dimensions Determined?
The minimum size for a particular RSA (known as the Design Standard) can
vary depending on the type of aircraft expected to use the runway.
Generally speaking, the largest and heaviest aircraft regularly operating
on a runway dictates the RSA size. At Kodiak Airport this aircraft is the
Boeing 737-400, operated by Alaska Airlines. The Boeing 737-400 falls
within wingspan category Group III, which is based on primarily on an
aircraft’s wingspan and tail height, and approach category of C, a
classification based on an aircraft’s speed when approaching a runway for
landing. (In case you were wondering, all of the B737-series aircraft
using or potentially using Kodiak Airport, such as the B737-200 or newer
-700/800/900 series, fall within the same design categories and would
require the same RSA dimensions.)
What are the RSA Standards for Kodiak Airport Runways?
The RSA design standards for the Boeing 737-400 are
Q 600 feet of approach (i.e., undershoot) protection on each end,
Q 1,000 feet of overrun protection on each end, and
Q 250 feet of lateral protection on either side of the runway
centerline, for the length of the runway. This equates to a
500-foot wide lateral RSA.
Since most runways support arrivals and departures in each direction, the
600 feet of approach protection is incorporated in the 1,000 feet of
overrun protection. The net result, for a runway regularly serviced by the
B737-400, is a 500-foot wide rectangular area centered upon the runway and
extending 1,000 feet beyond each runway end.
The description above is for what we might term a “traditional” runway
safety area. Another option that requires a smaller footprint and still
complies with FAA’s design standards is to use Engineered Materials
Arresting System (EMAS). I’ll have more information on EMAS in another
project update.
While RSA design standards are based on the largest and heaviest aircraft
regularly operating on a runway, smaller aircraft use the Kodiak Airport
and do not require the same RSA areas. The Dash-8, flown by Era Aviation
several times a day into the airport, is also a group III category aircraft
based on wingspan, but it falls into approach category A because it has a
slower approach speed for landings. Accordingly, the RSA design standard
for the Dash 8 is smaller than for the 737 aircraft: 300 ft wide by 600
long. As I discussed in the last project update, both the Dash-8 and the
B737-400 regularly use Runways 07/25 and 18/36. However, the required RSA
dimensions for those runways are based upon the design standard for the
larger aircraft, the B737-400.
Why is FAA Considering Expansion of the Kodiak Airport RSAs?
Public Law 109-115 states that not later than December 31, 2015, the owner
or operator of an airport certificated under 49 U.S.C. 44706 (such as the
Kodiak Airport) shall improve the airport's runway safety areas to comply
with the FAA design standards required by 14 Code of Federal Regulations
Part 139. In other words, the RSAs at Kodiak Airport must meet the FAA’s
design standards, contained in FAA Advisory Circular 150/5300-13, by the
end of 2015. The following information describes the extent of RSA
shortcoming on the runways ends at Kodiak Airport.
Runway 07/25, the (almost) east-west runways
Q Runway 07 Landings on this runway are from the west and
departures are toward the east. Although the RSA undershoot
protection on Runway 7 meets FAA standards, the proximity of
Barometer Mountain precludes virtually any landings by larger
commercial aircraft. Overrun standards are not met as there is no
RSA on the east runway end.
Q Runway 25 This runway is the opposite of Runway 07; landings are
from the east and departures would be toward the west. There is
no RSA to provide undershoot protection for aircraft approaching
over the water from the east, nor is there RSA on the west runway
end to provide overrun protection.
Runway 18/36, the north-south runways
Q Runway 18 Aircraft approach this runway for landings from the
north, over the Buskin River estuary, and take off to the south.
There is no RSA on the north runway end to provide undershoot
protection, nor is there RSA on the south end of the runway,
toward the Coast Guard station, for overrun protection.
Q Runway 36 Since this runway is oriented 180 degrees from Runway
18, the directions of operation are reversed. Aircraft approach
Runway 36 from the south and depart to the north. As with Runway
18, there is no RSA on either runway end for overrun or undershoot
protection.
Runway 11/29 These runways accommodate operations from and to the
southeast, marine end of the runway or the northwest, interior of
Kodiak Island. The runway safety area in place around Runway 11/29 is
300 feet wide for the length of the runway and extends 600 feet
beyond the ends of the runway. This RSA meets the design standards
for smaller commercial and larger general aviation aircraft, and no
further improvement is required.
Summary
Federal law requires that RSAs at airports such as Kodiak comply with FAA
design standards. Further, the owner or operator of such airports –
ADOT&PF is the operator at Kodiak – must meet those standards not later
than December 31, 2015. Two of the runways at Kodiak Airport, 18/36 and
07/25, do not meet design standards for the largest aircraft regularly
using those runways. FAA has initiated an environmental impact statement
to evaluate the effects of improving those RSAs.
I hope this information is useful. Thanks again for continuing to stay
involved in this project. Please don’t hesitate to call (271-5453) or
write (Leslie.Grey@faa.gov) if you have questions, comments or concerns.
Regards, Leslie
(See attached file: RSA Schematic.pdf)
Leslie A. Grey
Environmental Protection Specialist
FAA - Alaskan Region, Airports Division
907-271-5453
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