FEDERAL REGISTER

Wednesday, July 2, 2003

Weight-Based Restrictions at Airports/ Proposed Policy


DATES: Comments must be received by August 15, 2003. Comments that are
received after that date will be considered only to the extent possible.

ADDRESSES: The proposed policy is available for public review in the Dockets
Office, U.S. Department of Transportation, Room Plaza 401, 400 Seventh
Street, SW., Washington, DC 20590-0001. The documents have been filed under
FAA Docket Number FAA-2003-15495. The Dockets Office is open between 9:00
a.m. and 5:00 p.m., Monday through Friday, except Federal holidays. The
Dockets Office is on the plaza level of the Nassif Building at the
Department of Transportation at the above address. Also, you, may review
public dockets on the Internet at http://dms.dot.gov. Comments on the
proposed policy must be delivered on mailed, in duplicate, to: the Docket
Management System, U.S. Department of Transportation, Room Plaza 401, 400
Seventh Street, SW., Washington, DC 20590-0001. You must identify the docket
number "FAA Docket No FAA-2003-15495" at the beginning of your comments.
Commenters wishing to FAA to acknowledge receipt of their comments must
include a preaddressed, stamped postcard on which the following statement is
made: "Comments to FAA Docket No. FAA-2003-15495." The postcard will be date
stamped and mailed to the commenter. You may also submit comments through
the Internet to http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT: James White, Deputy Director, Office of
Airport Safety and Standards, AAS-2, Federal Aviation Administration, 800
Independence Ave. SW., Washington, DC 20591, telephone (202) 267-3053.

SUPPLEMENTARY INFORMATION: Airport operators that accept federal airport
development grants under the Airport Improvement Program (AIP), 49 U.S.C.
47101 et seq., enter into a standard grant agreement with the FAA. That
agreement contains certain assurances, including assurance no. 22, based on
the requirement in 49 U.S.C. 47107(a)(1). Grant assurance no. 22 reads, in
part:

"a. [The sponsor] will make the airport available as an airport for public
use on reasonable terms and without unjust discrimination to all types,
kinds and classes of aeronautical activities, including commercial
aeronautical activities offering services to the public at the airport."

At the same time, the FAA expects that airport sponsors will protect
airfield pavement from damage or early deterioration. Many airport projects
funded with the AIP grants involve pavement. As a result, both the FAA and
airport sponsors have a significant investment in airfield pavement, and an
interest in assuring that pavement remains in acceptable condition for its
design life, normally at least 20 years. The policy of assuring reasonable
access to the airport and the interest in protecting the investment in
airfield pavement are both extremely important, but is clear that they can
potentially work against each other in a particular case.

In February 2002, the Airports Division in an FAA regional office issued a
preliminary determination on the ability of a particular airport operator to
limit use of the airport according to aircraft weight. In that case the
weight limit effectively prohibited operation by aircraft heavier than the
aircraft considered in the design of the airport's pavement. The FAA
found, in summary, that the airport operator could limit use above the
design weight of the pavement, but that some operations above that weight
could and should be permitted, because they would have no measurable effect
on the pavement. The FAA has received several questions relating to the
policy underlying that determination.

In view of the importance of the policies at stake, we believe it is
appropriate to issue more specific guidance on the specific issue of
weight-based access restrictions.

The policy proposed in this notice provides more detailed guidance on how
the FAA will interpret Grant Assurance No. 22, in cases in which an airport
sponsor limits operation by aircraft above a certain weight in order to
preserve the integrity of airport pavement. The FAA requests comment on the
following statement of policy, and may modify the policy in accordance with
comments received on this notice. For any cases presented before a final
policy is issued, the FAA will apply the policy as proposed in this notice.

For the above reasons, the FAA proposes to adopt the following policy:

Operating Limitations to Protect Airport Pavements From the Effects of
Operations in Excess of Design Weight-Bearing Capacity

1. When designing new airport pavement or rehabilitating existing pavement,
airport operators design the pavement to accommodate the loads and
frequencies of the aircraft expected to use the airport over the period of
expected pavement life. A load-bearing capacity is then assigned to the
pavement based upon the most demanding aircraft. Once that pavement is
constructed, airport operators have a responsibility to protect the local
and Federal investment in the pavement. At the same time, airport operators
are encouraged to upgrade airport pavements for forecast increases in
aircraft size or operations, or if the number of operations and size of
aircraft increase over time beyond what was forecast.

2. Airport pavements are designed to accommodate a finite number of aircraft
operations, based on planning forecasts and experience. In most cases it
should not be necessary or appropriate to impose aircraft operating
restrictions to protect pavement from occasional operations of aircraft
which exceed the published pavement strength. Even in the exceptional case
in which the mix of aircraft types using the pavement becomes heavier over
time, a limitation on maximum weight of aircraft may not be warranted. It is
the nature of airport pavement to begin a gradual deterioration process as
soon as it is opened to traffic. A pavement designed for a specified number
of operations by an aircraft type of a particular weight will not be
immediately affected by some number of operations by heavier aircraft, up to
a point. In general, each 10% increase in weight of the most demanding
aircraft will decrease the number of design operations by 20-25%. The
original load-bearing capacity of pavement may be increased by surface
overlays or other pavement rehabilitation techniques. Therefore, some number
of operations by aircraft exceeding the design load-bearing capacity of
airport pavement by some degree will ordinarily not have a sufficient impact
to shorten its useful life. (The Airport/Facility Directory introductory
language notes that "[m]any airport pavements are capable of supporting
limited operations with gross weights of 25-50% in excess of the published
figures.").

3. However, where the airport operator reasonably believes that actual
damage or excessive wear has resulted or would result from operation of
aircraft of a particular weight (and particular gear configurations), then
the airport operator can limit those operations to the extent necessary to
prevent that damage or excessive wear.

4. The design load-bearing capacity of pavement is a guide to the
probability of adverse effects on pavement life. Design load-bearing
capacity is demonstrated by planning and engineering documents created at
the time the pavement was designed, constructed, rehabilitated or improved.
Testing to determine actual load-bearing capacity may be appropriate or
necessary where design information is unavailable or does not appear to
represent actual current condition of the pavement.

5. Any action by the airport operator to limit operations above the design
load-bearing capacity must be reasonable and unjustly discriminatory, and
would require evidence of the effect of operations at certain weights on the
pavement. Such limitations, if determined to be necessary, could include:

* Requiring particular taxi routes and parking areas for aircraft above a
certain weight, to avoid weaker areas;

* Requiring prior permission for operation by aircraft above the design
load-bearing capacity of the pavement (see examples in Exhibit 1);

* Permitting operations of such aircraft only up to a certain weight;

* Prohibiting all operations by aircraft exceeding a weight at which even a
small number of operations would significantly reduce pavement life.

* Assigning heavy aircraft a particular runway (through agreement with Air
Traffic Control) if operationally feasible.

Operating procedures, such as requiring use of designated taxiways and ramp
parking areas, are preferable to an outright ban or limit on the number of
operations. A limit on the number of operations and/or weight of operations
must be based on an analysis of pavement life using known pavement design
capacity, actual load-bearing capacity, and actual condition. That analysis
can be performed with the AAS-100 Pavement Design Software, based on
Advisory Circular (AC) 150/5320-6D, available on the FAA Airports web site.
An analysis is also required to assess the load-carrying capacity of
existing bridges, culverts, in-pavement light fixtures, and other structures
affected by the proposed traffic. Such structures are generally not capable
of supporting a single load application above design limits, and may
preclude any operations by heavier aircraft unless other taxi routes can be
specified. Guidance for those evaluations is stated in AC 150/5320-6D.

6. The airport operator may avoid any issue of reasonable, nondiscriminatory
access to the airport by accommodating current operations and bringing
pavement up to the standard for the current use of the airport as the
condition of the pavement requires.

7. This policy applies only to pavement weight-bearing capacity and pavement
condition, and does not apply to geometric airport design standards.

8. This policy applies only to the purpose of protecting an airport
operator's investment in pavement, and is not a substitute for noise
restrictions. If there is no showing of need to protect pavement life, or
the limit on airport use appears motivated by interest in mitigating noise
without going through processes that exist for such restrictions, an attempt
to limit aircraft by weight will be considered unreasonable. The FAA notes
that there are a few existing noise rules that include weight categories,
generally adopted before ANCA and the AAIA were enacted. Issues arising
under those rules will be addressed on a case-by-case basis.

Examples

Airport operators may experience demand for use of the airport by aircraft
that weigh more than the design load-bearing capacity of the airport
pavement. In some cases that demand can adversely affect pavement condition.
Ideally the airport operator should accommodate demand by upgrading
facilities. If that option is not practical, the airport operator can permit
reasonable access by these aircraft, while avoiding adverse effects on
existing pavement, by regulating the number and maximum weight of operations
on a prior-permission-required basis. The number and maximum weight of
operations permitted would vary according to the specific circumstances at
each airport, including:

* Pavement load-bearing capacity.

* The mix of aircraft operating at the airport. The heavier the aircraft,
the fewer operations it takes to have an effect on pavement life.

* Seasonal effects on pavement strength, for example wet or dry subgrade
conditions or very low or high pavement temperatures.

The following scenarios are not recommendations but simply examples of
limitations that might be appropriate in particular circumstances. Local
conditions may require more complex solutions. An engineering analysis will
be required in each case.

Scenario 1

The airport pavement is designed to 60,000 lb. dual-wheel load. Pavement
design and soil support conditions are known. Operations up to 60,000 lb.
are unrestricted, and the issue is how many flights should be permitted
above that weight.

The airport receives frequent operations by several aircraft types at 70,000
lb., and occasional operations at 105,000 lb., but very few operations by
other aircraft types in between those weights.

Reference to AC 150/5320-6D shows that on an annual basis up to xxxx
operations at 70,000 lb. and xx operations at 105,000 lb. together would
have no measurable effect on the life of the pavement, but more operations
at either weight would begin to shorten pavement life.

The operator could require prior permission for operations above 60,000 lb.
Permission would be granted on a first-come first-served basis, for xx
(xxxx/52) operations per week up to 70,000 lb. and for x (xx/52) operations
per week up to 110,000 lb.

Scenario 2

The airport pavement is designed to 100,000 lb., with dual-wheel gear
configuration. Pavement design and soil support conditions are known.

Most operations at the airport are well under 100,000 lb., but the airport
receives regular operations by various types of aircraft at weights from
100,000 lb. up to 135,000 lb. Operations up to 100,000 lb. are unrestricted,
and the issue is how many flights should be permitted above that weight.

Reference to AC 150/5320-6D shows that on an annual basis various
assortments of operations above 100,000 lb. can operate without measurable
effect on the life of the pavement. However, there is no single "right"
combination, because more operations at one weight will reduce the number
that can be permitted at another weight. Also, each flight at the heavier
end of the scale, e.g., 135,000 lb., has a disproportionately adverse effect
equal to several flights at the lower end of the scale, e.g., just above
100,000 lb.

There may be many ways to allocate limited operating rights for the various
types of aircraft that would use the airport over time, while controlling
the maximum cumulative stress on the airport's pavement. One way would
be to allocate operating permission by "points" rather than by number of
operations. While the numbers actually used would need to be validated using
AC 150/5320-6D, something like the following could be used:

Each operation 100,001 lb. to 110,000 lb.; 1 point.

Each operation 110,001 lb. to 120,000 lb.; 2 points.

Each operation 120,001 lb. to 130,000 lb.; 4 points.

Each operation 130,001 lb. to 140,000 lb.; 6 points.

If AC 150/5320-6D indicated that no combination of operations equal to an
annual usage of 1200 points would have an adverse effect on pavement life,
then the airport operator could allocate 23 points a week with no adverse
effects.

The operator would require prior permission for operations above 100,000 lb.
Permission would be granted on a first-come first-served basis, until the
weekly allocation of points was assigned.